• Sports drinks are designed to deliver a balanced amount of carbohydrate and fluid to allow an athlete to simultaneously rehydrate and refuel during and after exercise.
• According to various expert position stands, the composition which provides rapid delivery of fluid and fuel and maximises gastric tolerance and palatability is within the range of 4–8% (4–8 g/100 ml) carbohydrate and 23–69 mg/100 mL (10–30 mmol/L) sodium.¹
• Carbohydrates consumed during exercise can support or enhance performance via two different mechanisms: provision of fuel for the muscle and a mouth sensing benefit to the brain and central nervous system. Guidelines for carbohydrate intake during different sporting activities vary according to the importance of these effects.  
  • Performance benefits have been clearly demonstrated in a range of sporting events when carbohydrate is consumed during exercise to provide an additional fuel to the muscle.^2,3
  • Mouth sensing: the exposure of receptors in the mouth/oral cavity to carbohydrate creates a favourable response in the brain and central nervous system (CNS), decreasing the perception of effort and enhancing pacing strategies.^4,5
• There may be other roles for carbohydrate support during prolonged strenuous exercise that are of benefit to athlete health, particularly for high performance athletes. These roles are based on studies that investigate the acute response to exercise; further work is needed to determine if these actions translate into a reduced risk of illness and injury.
  • Consuming carbohydrate before, during and/or after prolonged intensive exercise may help to protect immune function by being associated with a reduction in the detrimental changes in cytokines and immune system cells normally induced by exercise stress.⁶
  • Such intake may also be beneficial to bone health by reducing the effect of exercise with low carbohydrate availability on markers of bone resorption.⁷
• The electrolyte content of sports drinks, particularly sodium, helps to preserve the thirst drive. Sodium concentrations of ~ 10–25 mmol/L enhance the palatability and voluntary consumption of fluids consumed during exercise, although higher sodium/electrolyte concentrations may increase fluid retention.
• The taste and temperature of sports drinks are also important factors in meeting hydration goals:-Studies show that athletes more closely match fluid intake to sweat losses when offered flavoured sports drinks compared to water.^8,9
  • Cool fluids are generally more palatable for athletes who are exercising in hot conditions or have become hot through the heat gain associated with high-intensity exercise; with studies showing that voluntary intake of cool drinks is increased.¹⁰
  • Sports drinks are suitable to serve in “slushie” (ice slurry) form for use pre- and during- exercise as part of a “cooling” strategy to assist comfort and thermoregulation during activities undertaken in hot environments.¹¹

• Commercially available sports drinks come in both ready-to-drink and powdered forms in a wide range of flavours which vary according to their carbohydrate and electrolyte content as well as the addition of other ingredients.
• The type and quantity of carbohydratesprovided in sports drinks varies according to the manufacturer, with factors such as taste, osmolarity (concentration of individual particles), intestinal absorption and gut tolerance being considered.
• Typical carbohydrate concentrations range from 6-8% (6-8g /100 ml), however some drinks vary from 2-14% carbohydrate and several low energy/”sugar free” varieties also exist:
  • Certain new varieties may contain ~14% carbohydrate and are designed to meet high fuel targets during endurance exercise. Some of these may be made with special techniques; for example, the use of pectin and alginate gel to create a “hydrogel” that is claimed to aid stomach emptying of the drink. Further research is needed to support these claims and athletes should ensure that they practice the use of more concentrated formulas to confirm tolerance and perceived benefit.
  • Low energy/‘sugar free’ varieties may be useful when fluid intake is desired without carbohydrate intake (e.g. protocols to “train low” or when attempting to decrease energy intake).
• Typical sodium concentrations range from ~20-40 mmol/L (~46-92 mg/100 ml), however some drinks are lower (<10 mmol) in sodium:
  • Lower sodium concentrations increase palatability and there for usually promote greater fluid intake.
  • Higher sodium concentrations target the replacement of sweat electrolyte losses, with greater effects on fluid absorption/retention and thus may be more effective in recovery after exercise.
  • Note that dedicated electrolyte supplements with higher sodium concentrations are discussed in the Electrolyte Replacement Supplements fact sheet).
• Other electrolytes (e.g. magnesium, potassium and calcium) may be included in sports drinks. Current evidence indicates that magnesium losses during exercise can be met by dietary means and it is unlikely that additional magnesium intake via sports drinks will enhance hydration goals or reduce cramping.
• Protein or amino acids (2% or 2 g/100 ml) can be found in a small number of sports drinks.
  • The case for consuming protein during exercise to enhance performance is contentious. A meta- analysis of the literature (11 studies) suggested a methodological bias in the current studies; benefits are seen with time to exhaustion protocols and when protein is added to sub-optimal intakes of carbohydrate. It was concluded that any ergogenic benefits may result from a generic effect of additional energy intake rather than a unique benefit of protein.¹²
  • It is possible that protein consumed during prolonged lower- or intermittent intensity exercise may assist with protein synthesis goals and recovery during intensified training or competition; however other everyday foods or sports food sources may be consumed to achieve this.
  • Further research is warranted, but the effects of amino acids/ protein on the flavour profile of a drink and gastrointestinal comfort should also be considered.

• Sports drinks provide a convenient option for simultaneously addressing fuel, fluid and electrolyte needs before, during and after exercise.
• Use pre-exercise: may be part of the pre-exercise meal or consumed immediately before exercise to enhance fluid and fuel status.
  • Pre-exercise “slushies” may be part of pre-cooling strategies for exercise in hot environments.
• Use during exercise: promotes hydration, fuelling and reduced perception of effort during exercise.
• Use post-exercise: can contribute to refuelling goals but other foods/sports products should be considered to provide a more nutrient-dense approach to total recovery needs.
  • Hydration: promotes voluntary drinking and fluid retention to assist the athlete to achieve a fluid intake plan that keeps the fluid deficit incurred during exercise to an acceptable level. Opportunities to drink fluids during sporting activities vary according to the rules and practical features of the sport.¹³
  • Fuelling: carbohydrates consumed provide an additional fuel source for the muscle according to the requirements of each sporting activity. See Table 1 for recommendations.
  • Mouth sensing: 5-10 second exposure of mouth/oral cavity to carbohydrate every 10-20 minutes stimulates reward centres in the brain to make the athlete feel better. Effect is repeatable throughout exercise and can directly enhance performance of shorter events (45-75 min) as well as provide additional benefit in longer events.
• Delivery of carbohydrate consumed during exercise to the muscle is largely influenced by the rate at which it can be absorbed in the small intestine. Typically, ingesting glucose-based carbohydrates (e.g. sucrose, glucose polymers, maltodextrin) at rates in excess of ~ 60 g/h during exercise does not lead to additional performance benefits. In fact, because intestinal glucose transporters (called SGLT1) are saturated at this level, excessive carbohydrate intake can cause gut discomfort/problems that impair performance.
  • The gut can be ‘trained’ by consuming carbohydrates during exercise to maximise the number and activity of the SCGT1 transporters, thus enhancing glucose uptake and reducing gut symptoms.^14,15
  • In addition, some newer sports drinks and sports foods contain ‘multiple transportable carbohydrates’ - a blend of carbohydrates such as glucose and fructose which are absorbed via different transporter molecules in the intestine to overcome the usual bottleneck on a single transport system.
  • Studies have shown that when carbohydrates are consumed at high rates (> 60 g/h) during exercise to meet new guidelines for prolonged strenuous events, drinks containing multiple transportable carbohydrates are more effective than glucose-based products in maintaining gut comfort, promoting muscle carbohydrate oxidation and enhancing performance.¹⁶
• The composition of sports drinks provides a generic balance between fluid and carbohydrate needs across a range of sports. The relationship between fluid and fuel needs may vary according to the environment, the athlete’s nutritional preparation and the demands of the exercise.
  • If fluid needs are greater than carbohydrate needs: sports drinks with lower carbohydrate content or diluted sports drinks may be used.
  • If carbohydrate needs are greater than fluid needs: sports drinks with higher carbohydrate content may be used or supplemented with sports gel/ sport bar/ sport confectionery.

Table 1: Guidelines for carbohydrate intake during sporting activities ¹⁷

Unnecessary expense

Sports drinks are not needed at every training session and may be an unnecessary expense.

Unnecessary energy intake

Athletes need to consider their physique goals and total nutritional goals when deciding whether to consume sports drinks. In the case of athletes who have short- or long-term restrictions on dietary energy intake, overuse of energy-dense fluids such as sports drinks may create problems with energy balance and overall nutrient density of the diet.

Dental erosion

Sports drinks, like other carbohydrate-containing fluids such as soft drinks and fruit juices, have been shown to contribute to dental erosion. To help reduce the potential impact of sports drinks on dental health, athletes should consider the follow options when they are practical or able to be balanced with the sports nutrition plan.

• Minimise the contact time the sports drink has with the teeth and avoid holding or swishing the drink around the mouth. A straw or squeezy bottle can also minimise contact time with the teeth by directing fluids towards the back of the mouth.
• Use a water chaser immediately after consuming a sports drink to rinse the mouth out.
• Where practical, consume dairy products after the session or chew sugar free gum immediately after consumption of the sports drink.
• Avoid brushing teeth for at least 30 minutes after consuming sports drink to allow tooth enamel to re-harden.¹⁸

Gut discomfort

• Some athletes report that sports drinks cause gut discomfort or make them feel unwell. While some athletes may not tolerate sports drinks well, the following strategies can help to minimise problems.
  • Dehydration increases the risk of gastrointestinal problems during exercise and is often the cause of such complaints. Practicing fluid intake strategies during training can assist in preventing dehydration as well as helping to overcome problems such as dislike of the taste, mouthfeel of the drink and gastrointestinal discomfort.
  • ‘Gut training’ – deliberately consuming a gradually increasing volume and concentration of sports drink during workouts - can allow the gut to develop better capacity to absorb carbohydrate and feel comfortable.
  • The use of sports drinks with multiple transportable carbohydrates may assist in maximising gastrointestinal comfort, particularly when carbohydrate is consumed at high rates of intake (> 60 g/h).
• Individuals with fructose malabsorption or FODMAP intolerance should be aware of the fructose content of sports drinks containing multiple transportable carbohydrates.

Interference with opportunities for training adaptation

Some athletes may periodise their carbohydrate intake to help support training adaptations. This may include the prescription of workouts in which there is “low carbohydrate availability” (i.e. the session is undertaken with low muscle glycogen stores and/or after an overnight fast). This strategy may increase some of the important adaptive responses to exercise. Therefore, on some occasions, an athlete may deliberately choose not to consume a sports drink during the session or during the first part of a session.^19,20

1. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. (2007). American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc, 39 (2), 377-90.
2. Phillips SM,Sproule J,Turner AP. (2011). Carbohydrate ingestion during team games exercise: current knowledge and areas for future investigation. Sports Med. 41(7), 559-85.
3. Stellingwerff T, Cox GR. (2014). Systematic review: Carbohydrate supplementation on exercise performance or capacityof varying durations. Appl Physiol Nutr Metab, 39(9), 998-1011.
4. Jeukendrup AE. (2013). Oral carbohydrate rinse: placebo or beneficial? Curr Sports Med Rep. 12(4), 222-227.
5. Burke LM, Maughan RJ. (2015). The Governor has a sweet tooth - mouth sensing of nutrients to enhance sportsperformance. Eur J Sport Sci, 15(1), 29-40
6. Peake JM, Neubauer O, Walsh NP, Simpson RJ. (2017). Recovery of the immune system after exercise. J Appl Physiol , 122(5), 1077-1087.
7. Sale C, Varley I, Jones TW, James RM, Tang JC, Fraser WD, Greeves JP.  (2015). Effect of carbohydrate feeding on the bone metabolic response to running. J Appl Physiol. 119(7), 824-30.
8. Minehan MR, Riley MD and Burke LM. (2002). Effect of flavor and awareness of kilojoule content of drinks on preference and fluid balance in team sports. Int J Sport Nutr Exerc Metab, 12(1), 81-92.
9. Maughan RJ and Leiper JB. (1993). Post-exercise rehydration in man: effects of voluntary intake of four different beverages. Med Sci Sports Exerc, 25, 34-35.
10. Burdon CA, Johnson NA, Chapman PG, O’Connor HT. (2012). Influence of beverage temperature on palatability andfluid ingestion during endurance exercise: a systematic review. Int J Sport Nutr Exerc Metab, 22(3), 199-21.
11. Ross M, Abbiss C, Laursen P, Martin D, and Burke LM. (2013). Precooling methods and their effects on athletic performance: a systematic review and practical applications. Sports Med, 43, 207-225.
12. Stearns RL, Emmanuel H, Volek JS, Casa DJ. (2010). Effects of ingesting protein in combination with carbohydrate during exercise on endurance performance: a systematic review with meta-analysis. J Strength Cond Res, 24(8), 2192-202.
13. Garth AK, Burke LM. (2013). What do athletes drink during competitive sporting activities? Sports Med. 43(7), 539-64.
14. Costa RJS, Miall A, Khoo A, Rauch C, Snipe R, Camões-Costa V, Gibson P. (2017). Gut-training: the impact of twoweeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, andrunning performance. Appl Physiol Nutr Metab, 42(5), 547-557.
15. Miall A, Khoo A, Rauch C, Snipe RMJ, Camões-Costa VL, Gibson PR, Costa RJS. (2018). Two weeks of repetitive gut-challenge reduce exercise-associated gastrointestinal symptoms and malabsorption. Scand J Med Sci Sports, 28(2), 630-640.
16. Jeukendrup AE. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Curr Opin Clin Nutr Metab Care, 13(4), 452-457.
17. Burke LM, Hawley JA, Wong SH, Jeukendrup AE. (2011). Carbohydrates for training and competition. J Sports Sci, 8, 1-11.
18. Needleman I, Ashley P, Fairbrother T, Fine P, Gallagher J, Kings D, Maugha RJ, Melin AK, Naylor M. (2018). Nutrition and oral health in sport: time for action. Br J Sports Med, 52(23), 1483-1484.
19. Impey SG, Hearris MA, Hammond KM, Bartlett JD, Louis J, Close GL, Morton JP. (2018). Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis. Sports Med, 48(5), 1031-1048.
20. Burke LM, Hawley JA, Jeukendrup A, Morton JP, Stellingwerff T, Maughan RJ. (2018). Toward a Common Understanding of Diet-Exercise Strategies to Manipulate Fuel Availability for Training and Competition Preparation in Endurance Sport. Int J Sport Nutr Exerc Metab, 28(5), 451-463.

• Sports gels are a highly concentrated source of carbohydrate (65–70% or 65–75 g/100 ml) in a form (“honey consistency”) that is easily consumed and quickly digested. Sports gels provide a compact and portable source of carbohydrate which can easily be consumed immediately before or during exercise to contribute to carbohydrate intake targets.
• Carbohydrates consumed during exercise can support or enhance performance via two different mechanisms: provision of fuel for the muscle and a mouth sensing benefit to the brain and central nervous system (CNS). Guidelines for carbohydrate intake during different sporting activities vary according to the importance of these effects.
• There may be other roles for carbohydrate support during prolonged strenuous exercise that are of benefit to athlete health, particularly for high performance athletes. These roles are based on studies that investigate the acute response to exercise; further work is needed to determine if these actions translate into a reduced risk of illness and injury.
  • Consuming carbohydrate before, during and/or after prolonged intensive exercise may help to protect immune function by being associated with a reduction in the detrimental changes in cytokines and immune system cells normally induced by exercise stress.¹
  • Such intake may also be beneficial to bone health by reducing the effect of exercise with low carbohydrate availability on markers of bone resorption.²
• Many gels also contain electrolytes, particularly sodium, to assist with thirst drive and fluid retention, or to contribute to sodium balance during ultra-endurance events (see Electrolyte replacement fact sheet).

• A sachet of a typical sports gel provides:
  • 20-30 g carbohydrate
  • ~350-500 kJ (80-120 kcal)
• While sodium content is typically low (< 100 mg per gel), some brands contain higher amounts (up to 300 mg).
• Some gels contain caffeine (25-100 mg) and as such, may be strategically used to simultaneously achieve specified carbohydrate & caffeine intake goals (see Caffeine fact sheet for details).
• Some gets contain menthol (0.01-0.7%) and as such, may be strategically used to simultaneously achieve specified carbohydrate & menthol intake goals (see Menthol fact sheet for details).
• The type and quantity of carbohydrates provided in gels varies according to the brand.
  • Some gels contain “multiple transportable carbohydrates” — a blend of carbohydrates such as glucose and fructose which are absorbed from the intestine via different transporter molecules (see below).
• Gels are substantially more concentrated in carbohydrate than sports drinks to provide a large fuel boost in a single serve. The majority should be consumed with water or other dilute fluids, which can separately address hydration needs for the activity and reduce the net carbohydrate concentration to reduce risk of gut upsets. A small number of specifically labelled “isotonic” gels are formulated to be consumed without water.
• Despite recommendations in early sports nutrition guidelines against consuming concentrated forms of carbohydrate during exercise, recent studies have shown that sports gels consumed with water during moderate intensity exercise provide a similar pattern of carbohydrate delivery and oxidation by the muscle as sports drinks and are well tolerated by most athletes.^3,4
• Although each gel provides ~ 20–30 g of carbohydrate, decanting into custom made flasks allows the gel to be consumed in more variable volumes. In some sports, a gel can also be added to a drink bottle of water during the event to create a more dilute “sports drink”.
• The consistency of sports gels is likely to increase the amount of time and mouth contact associated with the intake of carbohydrate compared with sports drinks. This may increase the ability of gels to provide a performance benefit via the stimulatory effect of carbohydrate sensing mouth receptors on the brain and central nervous system.

• Use pre-exercise: sports gels provide a low fibre and compact carbohydrate source for pre-event fuelling for athletes who are unable to tolerate regular foods and fluids.
• Use during exercise: to supply carbohydrate to the muscle and CNS.
• Use post-exercise: can contribute to refuelling goals but other foods/sports products should be considered to allow a more nutrient-dense approach to total recovery needs.
  • Fuelling: supplies easily consumed carbohydrates to provide an additional fuel source for the muscle according to the requirements of each sporting activity. Performance benefits have been clearly demonstrated in a range of sporting events as a result of this strategy.^5,6 See Table 1 for guidelines.
  • Mouth sensing: the exposure of receptors in the mouth/oral cavity to carbohydrate creates a favourable response in the brain and CNS, decreasing the perception of effort.⁷

Table 1: Guidelines for carbohydrate intake during sporting activities ⁸

• Delivery of carbohydrate consumed during exercise to the muscle is largely influenced by the rate at which it can be absorbed in the small intestine. Typically, ingesting glucose based carbohydrates (e.g. sucrose, glucose polymers, maltodextrin) at rates in excess of ~ 60 g/h during exercise does not lead to additional performance benefits. In fact, because intestinal glucose transporters (called SGLT1) are saturated at this level, excessive carbohydrate intake can cause gut discomfort/problems that impair performance.
  • The gut can be ‘trained’ by consuming carbohydrates during exercise to maximise the number and activity of the SCGT1 transporters, thus enhancing glucose uptake and reducing gut symptoms.^9,10
  • In addition, some newer sports foods contain ‘multiple transportable carbohydrates’ - a blend of carbohydrates such as glucose and fructose which are absorbed via different transporter molecules in the intestine to overcome the usual bottleneck on a single transport system.
  • Studies have shown that when carbohydrates are consumed at high rates (> 60 g/h) during exercise to meet new guidelines for prolonged strenuous events, drinks containing multiple transportable carbohydrates are more effective than glucose-based products in maintaining gut comfort, promoting muscle carbohydrate oxidation and enhancing performance.¹¹

Unnecessary expense

Sports Gels are not needed at every training session and may be an unnecessary expense.

Unnecessary energy intake

Athletes need to consider their physique goals and total nutritional goals when deciding whether to consume sports gels. In the case of athletes who have short- or long-term restrictions on dietary energy intake, overuse of energy-dense sports foods such as sports gels may create problems with energy balance and overall nutrient density of the diet.

Dental erosion

• Repeated exposure of the teeth to sticky forms of carbohydrate is not ideal for dental health. To help reduce the potential impact of sports gels on dental health, athletes should consider the follow options when they are practical or able to be balanced with the sports nutrition plan.
• Minimise the contact time between the teeth and the sports gel and rinse out the mouth with water once the gel has been consumed.
• Where practical, consume dairy products immediate after the session, or chew sugar free gum immediately after consumption of the sports gel.
• Avoid brushing teeth for at least 30 minutes after consuming sports gels to allow tooth enamel to re- harden.¹²

Gut discomfort

• Athletes should practice the use of gels and assess tolerance during training sessions if they are intended for use during competition. Research in laboratories and in the field has shown that the use of sports gels is well tolerated by most athletes. However, a small number of athletes suffer from significant gastrointestinal issues and may need an individualised protocol ^3,4. The following strategies can help to minimise problems.
  • Sports gels should be consumed with adequate fluid to meet hydration needs and to improve gastrointestinal tolerance.
  • ‘Gut training’ – deliberately consuming a gradually increasing volume and concentration of sports gels during workouts - can allow the gut to develop better capacity to absorb carbohydrate and feel comfortable.
  • The use of sports gels with multiple transportable carbohydrates may assist in maximising gastrointestinal comfort, particularly when carbohydrate is consumed at high rates of intake (> 60 g/h).
• Individuals with fructose malabsorption or FODMAP intolerance should be aware of the fructose content of sports gels containing multiple transportable carbohydrates.

Interference with opportunities for training adaptation

Some athletes may periodise their carbohydrate intake to help support training adaptations. This may include the prescription of workouts in which there is “low carbohydrate availability” (i.e. the session is undertaken with low muscle glycogen stores and/or after an overnight fast). This strategy may increase some of the important adaptive responses to exercise. Therefore, on some occasions, an athlete may deliberately choose not to consume gels or other forms of carbohydrate during the first part of a session.^13,14

1. Peake JM, Neubauer O, Walsh NP, Simpson RJ. (2017). Recovery of the immune system after exercise. J Appl Physiol, 122(5), 1077-1087.
2. Sale C, Varley I, Jones TW, James RM, Tang JC, Fraser WD, Greeves JP. (2015). Effect of carbohydrate feeding on the bone metabolic response to running. J Appl Physiol, 119(7), 824-30.
3. Pfeiffer B, Cotterill A, Grathwohl D, Stellingwerff T, Jeukendrup AE. (2009). The effect of carbohydrate gels on gastrointestinal tolerance during a 16-km run. Int J Sport Nutr Exerc Metab, 19(5), 485-503.
4. Pfeiffer B, Stellingwerff T, Zaltas E, Jeukendrup AE. (2010). CHO oxidation from a CHO gel compared with a drink during exercise. Med Sci Sports Exerc, 42(11), 2038-45.
5. Phillips SM, Sproule J, Turner AP. (2011). Carbohydrate ingestion during team games exercise: current knowledge and areas for future investigation. Sports Med, 41(7), 559-85.
6. Stellingwerff T, Cox GR. (2014). Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab, 39(9), 998-1011.
7. Burke LM, Maughan RJ. (2015). The Governor has a sweet tooth - mouth sensing of nutrients to enhance sports performance. Eur J Sport Sci, 15(1), 29-40.
8. Burke LM, Hawley JA, Wong SH, Jeukendrup AE. (2011). Carbohydrates for training and competition. J Sports Sci, 8, 1-11.
9. Costa RJS, Miall A, Khoo A, Rauch C, Snipe R, Camões-Costa V, Gibson P. (2017). Gut- training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Appl Physiol Nutr Metab, 42(5), 547-557.
10. Miall A, Khoo A, Rauch C, Snipe RMJ, Camões-Costa VL, Gibson PR, Costa RJS. (2018). Two weeks of repetitive gut- challenge reduce exerciseassociated gastrointestinal symptoms and malabsorption. Scand J Med Sci Sports, 28(2), 630-640.
11. Jeukendrup AE. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Curr Opin Clin Nutr Metab Care, 13(4), 452-457.
12. Needleman I, Ashley P, Fairbrother T, Fine P, Gallagher J, Kings D, Maugha RJ, Melin AK, Naylor M. (2018). Nutrition and oral health in sport: time for action. Br J Sports Med, 52(23), 1483-1484.
13. Impey SG, Hearris MA, Hammond KM, Bartlett JD, Louis J, Close GL, Morton JP. (2018). Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis. Sports Med, 48(5), 1031-1048.
14. Burke LM, Hawley JA, Jeukendrup A, Morton JP, Stellingwerff T, Maughan RJ. (2018). Toward a Common Understanding of Diet-Exercise Strategies to Manipulate Fuel Availability for Training and Competition Preparation in Endurance Sport. Int J Sport Nutr Exerc Metab. 28(5), 451-463.

Sports confectionery, often called “sports chews” provide a highly concentrated source of carbohydrate in a chewy jelly bean/jube form that is easily consumed and quickly digested. These products provide an alternative or additional source of carbohydrate to consume during exercise. They are typically provided in packets or pouches that are particularly suited for situations where consumption of smaller serves of carbohydrate can be managed at frequent intervals.

Carbohydrates consumed during exercise can support or enhance performance via two different mechanisms: provision of fuel for the muscle and a mouth sensing benefit to the brain and central nervous system. Guidelines for carbohydrate intake during different sporting activities vary according to the importance of these effects.

There may be other roles for carbohydrate support during prolonged strenuous exercise that are of benefit to athlete health, particularly for high performance athletes. These roles are based on studies that investigate the acute response to exercise; further work is needed to determine if these actions translate into a reduced risk of illness and injury.

• Consuming carbohydrate before, during and/or after prolonged intensive exercise may help to protect immune function by being associated with a reduction in the detrimental changes in cytokines and immune system cells normally induced by exercise stress.¹
• Such intake may also be beneficial to bone health by reducing the effect of exercise with low carbohydrate availability on markers of bone resorption.²

New products are appearing in this range to boost the variants of flavour, size and consistency of individual pieces, and the addition of other “active ingredients” or forms of carbohydrate. Note, however that many products are similar to everyday jelly confectionery. Typical carbohydrate content ranges from 75–90% by weight (75–90 g/100 g) or 4-6 g per piece.

• Typical sodium content ranges from 150-300mg / 100g, although certain varieties are very low.
• Some varieties contain other active ingredients such as caffeine.
• Some varieties of sports confectionery contain “multiple transportable carbohydrates” — a blend of carbohydrates such as glucose and fructose which are absorbed from the intestine via different transporter molecules (see below).

Sports confectionery should be consumed with water or other dilute fluids, which can separately address hydration needs for the activity. This fluid intake will also reduce the net carbohydrate concentration to reduce the risk of gut upsets.

It is noted that early sports nutrition guidelines warned against consuming concentrated forms of carbohydrate during exercise. However, recent studies have shown that sports gels consumed with water during moderate intensity exercise are well tolerated and provide a similar pattern of carbohydrate delivery and oxidation by the muscle to sports drinks. This is likely to be the case for sports confectionery (see Sports Gel fact sheet).

Sports confectionery are suitable for use in the same situations as sports gels, but offer more flexibility with timing of intake since individual pieces can be consumed at more frequent intervals.

• Use pre-exercise: sports confectionery provide a low fibre and compact carbohydrate source for pre-event fuelling for athletes who are unable to tolerate regular foods and fluids
• Use during exercise: to supply carbohydrate to the muscle and central nervous system
• Use post-exercise: can contribute to refuelling goals but other foods/sports products should be considered to provide a more nutrient-dense approach to total recovery needs.
  • Fuelling: supplies easily consumed carbohydrates to provide an additional fuel source for the muscle according to the requirements of each sporting activity. Performance benefits have been clearly demonstrated in a range of sporting events as a result of this strategy.^3,4. See Table 1 for recommendations.
  • Mouth sensing: the exposure of receptors in the mouth/oral cavity to carbohydrate creates a favourable response in the brain and central nervous system (CNS), decreasing the perception of effort and pacing strategies.^5,6

Table 1: Guidelines for carbohydrate intake during sporting activities ⁷

Exercise delivery of carbohydrate consumed during exercise to the muscle is largely influenced by the rate at which it can be absorbed in the small intestine. Typically, ingesting glucose based carbohydrates (e.g. sucrose, glucose polymers, maltodextrin) at rates in excess of ~ 60 g/h during exercise does not lead to additional performance benefits. In fact, because intestinal glucose transporters (called SGLT1) are saturated at this level, excessive carbohydrate intake can cause gut discomfort/problems that impair performance.

• The gut can be ‘trained’ by consuming carbohydrates during exercise to maximise the number and activity of the SCGT1 transporters, thus enhancing glucose uptake and reducing gut symptoms.^8,9
• In addition, some newer sports foods contain ‘multiple transportable carbohydrates’ - a blend of carbohydrates such as glucose and fructose which are absorbed via different transporter molecules in the intestine to overcome the usual bottleneck on a single transport system.
• Studies have shown that when carbohydrates are consumed at high rates (> 60 g/h) during exercise to meet new guidelines for prolonged strenuous events, sports foods containing multiple transportable carbohydrates are more effective than glucose-based products in maintaining gut comfort, promoting muscle carbohydrate oxidation and enhancing performance.¹⁰

Unnecessary expense

Sports confectionery are not needed at every training session and may be an unnecessary expense.

Unnecessary energy intake

Athletes should consider their physique goals and total nutritional goals when deciding whether to consume sports confectionery around exercise. In the case of athletes who have short- or long-term restrictions on dietary energy intake, overuse of energy-dense sports foods such as sports confectionery may create problems with energy balance and overall nutrient density of the diet.

Sports confectionery should be used for the specific conditions for which they are intended rather than as a general snack. Sports confectionery is an expensive alternative to general jelly confectionery (“lollies”), or to regular food and fluid choices. This may be warranted if there is a benefit associated with a specific size or consistency of the confectionery or the presence of other “active ingredients” (e.g. caffeine, electrolytes).

Dental erosion

Repeated exposure of the teeth to sticky forms of carbohydrate is not ideal for dental health. To help reduce the potential impact of sports confectionery on dental health, athletes should consider the follow options when they are practical or able to be balanced with the sports nutrition plan.

• Minimise the contact time between the sports confectionery and the teeth, and rinse the mouth with water after finishing the confectionery.
• Where practical, consume dairy products after the session or chew sugar-free gum immediately after consumption of the sports confectionery.
• Avoid brushing teeth for at least 30 minutes after consuming sports confectionery to allow tooth enamel to re-harden.

Gut discomfort

Although most athletes tolerate sports confectionery well, it is likely that a small number of athletes will suffer from significant gastrointestinal issues and may need an individualised protocol. Sports confectionery should be consumed with adequate fluid to meet hydration needs and to improve gastrointestinal tolerance. The following strategies can help to minimise problems.

• Sports confectionery should be consumed with adequate fluid to meet hydration needs and to improve gastrointestinal tolerance.
• ‘Gut training’ – deliberately consuming a gradually increasing amount and concentration of carbohydrate during workouts - can allow the gut to develop better capacity to absorb carbohydrate and feel comfortable.
• The use of sports confectionery with multiple transportable carbohydrates may assist in maximising gastrointestinal comfort, particularly when carbohydrate is consumed at high rates of intake (> 60 g/h).
• Individuals with fructose malabsorption or FODMAP intolerance should be aware of the fructose content of sports confectionery containing multiple transportable carbohydrates.

Interference with opportunities for training adaptation

Some athletes may periodise their carbohydrate intake to help support training adaptations. This may include the prescription of workouts in which there is “low carbohydrate availability” (i.e. the session is undertaken with low muscle glycogen stores and/or after an overnight fast). This strategy may increase some of the important adaptive responses to exercise. Therefore, on some occasions, an athlete may deliberately choose not to consume carbohydrate during the first part of a session.^11,12

1. Peake JM, Neubauer O, Walsh NP, Simpson RJ. (2017). Recovery of the immune system after exercise. J Appl Physiol , 122 (5), 1077-1087.
2. Sale C, Varley I, Jones TW, James RM, Tang JC, Fraser WD, Greeves JP. (2015). Effect of carbohydrate feeding on the bone metabolic response to running. J Appl Physiol. 119 (7), 824-30.
3. Phillips SM, Sproule J, Turner AP. (2011). Carbohydrate ingestion during team games exercise: current knowledge and areas for future investigation. Sports Med. 41 (7), 559-85.
4. Stellingwerff T, Cox GR. (2014). Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab. 39 (9), 998.
5. Jeukendrup AE. (2013). Oral carbohydrate rinse: placebo or beneficial? Curr Sports Med Rep. 12 (4), 222-227.
6. Burke LM, Maughan RJ. (2015). The Governor has a sweet tooth - mouth sensing of nutrients to enhance sports performance. Eur J Sport Sci. 15 (1), 29-40
7. Burke LM, Hawley JA, Wong SH, Jeukendrup AE. (2011). Carbohydrates for training and competition. J Sports Sci. 8, 1-11.
8. Costa RJS, Miall A, Khoo A, Rauch C, Snipe R, Camões-Costa V, Gibson P. (2017). Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Appl Physiol Nutr Metab. 42 (5), 547-557.
9. Miall A, Khoo A, Rauch C, Snipe RMJ, Camões-Costa VL, Gibson PR, Costa RJS. (2017). Two weeks of repetitive gut- challenge reduce exerciseassociated gastrointestinal symptoms and malabsorption. Scand J Med Sci Sports.
10. Jeukendrup AE. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Curr Opin Clin Nutr Metab Care, 13 (4), 452-457.
11. Impey SG, Hearris MA, Hammond KM, Bartlett JD, Louis J, Close GL, Morton JP. (2018). Fuel for the Work Required: A Theoretical Framework for Carbohydrate Periodization and the Glycogen Threshold Hypothesis. Sports Med. 48 (5), 1031-1048.
12. Burke LM, Hawley JA, Jeukendrup A, Morton JP, Stellingwerff T, Maughan RJ. (2018). Toward a Common Understanding of Diet-Exercise Strategies to Manipulate Fuel Availability for Training and Competition Preparation in Endurance Sport. Int J Sport Nutr Exerc Metab. 28 (5), 451-463.

• Sports or energy bars provide a compact and portable source of carbohydrate that can be easily consumed before or during exercise to contribute to carbohydrate intake targets.
• Carbohydrates consumed during exercise can support or enhance performance via two different mechanisms: provision of fuel to the muscle and a mouth sensing benefit to the brain and central nervous system. Guidelines for carbohydrate intake during different sporting activities vary according to the importance of these effects.
• There may be other roles for carbohydrate intake during prolonged strenuous exercise that are of benefit to athlete health, particularly for high performance athletes. These roles are based on studies that investigate the acute response to exercise; further work is needed to determine if these actions translate into a reduced risk of illness and injury.
  • Consuming carbohydrate before, during and/or after prolonged intensive exercise may help to protect immune function by being associated with a reduction in the detrimental changes in cytokines and immune system cells normally induced by exercise stress¹.
  • Such intake may also be beneficial to bone health by reducing the effect of exercise with low carbohydrate availability on markers of bone resorption².
• Although many athletes focus on liquid forms of carbohydrate during exercise (e.g. sports drinks or more concentrated gels) to address fluid replacement as well as fuel needs, studies show that solid forms of carbohydrate can also be well tolerated and are able to supply a rapid fuel source to the muscle3. Sports/energy bars offer the advantage of being a more compact and convenient fuel source for scenarios in which the athlete needs to transport their own nutritional support.

• Sports/energy bars typically focus on providing carbohydrate around exercise sessions and have two presentation forms with different characteristics around nutrient content and gut tolerance during exercise:
  • Chewy, low fibre, blended products (e.g. “powerbar”). These bars are typically used as a carbohydrate source for higher intensity endurance and ultra-endurance events/workouts where a low fibre content may assist with gut tolerance.
  • “Granola bar” like products with recognisable food ingredients (e.g. “Clif bar”). These are more suited to longer events of lower intensity where the increased fibre content can be better tolerated and flavour fatigue creates a need for a greater range of taste and texture choices.

Note: bars with a more diverse nutrient composition, including a higher protein content, are covered in a separate fact sheet on mixed macronutrient products.

• Use pre-exercise: provides a low fibre carbohydrate source to assist the pre-event fuelling goals of athletes who are unable to tolerate regular foods and fluids
• Use during exercise: can supply carbohydrate to the muscle and central nervous system
• Use post-exercise: can contribute to post-exercise refuelling. Note that other foods/sports products should also be considered in post-exercise meals/snacks to address total recovery needs.
• Travel: Provides a compact and convenient option while travelling either locally or internationally for training or competition, with the extended shelf-life and portability making access to trialled and familiar fuelling options easier.

Sports bar ingestion during exercise provides an additional fuel source for the muscle according to the requirements of each sporting activity. Performance benefits have been clearly demonstrated in a range of sporting events as a result of this strategy4,5. Furthermore, exposure of receptors in the mouth/oral cavity to carbohydrate creates a favourable response in the brain and central nervous system (CNS), decreasing the perception of effort and pacing strategies⁶. Delivery of carbohydrate consumed during exercise to the muscle is largely influenced by the rate at which it can be absorbed by the small intestine. Typically, ingesting glucose-based carbohydrates (e.g. sucrose, glucose polymers, maltodextrin) at rates in excess of ~ 60 g/h during exercise does not lead to additional performance benefits. In fact, because intestinal glucose transporters (called SGLT1) are saturated at this level, excessive carbohydrate intake can cause gut discomfort/problems that impair performance. See Table 1 for guidance on carbohydrate ingestion rates during exercise.

• The gut can be ‘trained’ by consuming carbohydrates during exercise to maximise the number and activity of the SCGT1 transporters, thus enhancing glucose uptake and reducing gut symptoms^7,8.
• In addition, some newer sports foods contain ‘multiple transportable carbohydrates’ - a blend of carbohydrates such as glucose and fructose which are absorbed via different transporter molecules in the intestine to overcome the usual bottleneck of a single transport system.
• Studies have shown that when carbohydrates are consumed at high rates (> 60 g/h) during exercise to meet new guidelines for prolonged strenuous events, sports foods containing multiple transportable carbohydrates are more effective than glucose-based products in maintaining gut comfort, promoting muscle carbohydrate oxidation and enhancing performance⁹.

Table 1: Guidelines for carbohydrate intake during sporting activities¹⁰

Unnecessary expense

Sports bars are not needed at every training session and may be an unnecessary expense.

Excess energy intake

Athletes need to consider their physique goals and total nutritional goals when deciding whether to consume sports/energy bars. In the case of athletes who have short- or long-term restrictions on dietary energy intake, overuse of energy-dense sports foods such as sports bars may create problems with energy balance and the overall nutrient density of the diet.

Gut discomfort

• Athletes should practice their use of bars pre- and during training sessions to assess tolerance if they are intended for use during competition. Some athletes experience significant gastrointestinal issues and may need an individualised protocol. The following strategies can help to minimise problems:
  • Consume sports bars with adequate fluid to meet hydration needs and to improve gastrointestinal tolerance.
  • ‘Gut training’ – deliberately consuming a gradually increasing amount of carbohydrate via products such as sports bars during workouts can allow the gut to develop better capacity to absorb carbohydrate and improve comfort.
  • The use of sports bars with multiple transportable carbohydrates may assist in maximising gastrointestinal comfort, particularly when carbohydrate is consumed at high rates of intake (> 60 g/h).
• Individuals with fructose malabsorption or FODMAP intolerance should be aware of the fructose content or additions of ingredients like inulin in sports bars containing multiple transportable carbohydrates.

Dental erosion

• Sports/energy bars, like other sticky carbohydrate-containing foods are likely to contribute to dental erosion. To help reduce the potential impact of sports bars on dental health, athletes should consider the following options when they are realistic within the sports nutrition plan.
  • Minimise the length of exposure between the teeth and the sports bar, and drink water after consuming a sports bar to rinse the mouth out
  • Where practical, consume dairy products immediately after exercise or chew sugar free gum immediately after consumption of the sports bar
  • Avoid brushing teeth for at least 30 minutes after consuming a sports bar to allow tooth enamel to re-harden¹¹.

Interference with opportunities for training adaptation

The optimal training program may include the periodisation of workouts in which there is “low carbohydrate availability” (i.e. the session is undertaken with low muscle glycogen stores and/or after an overnight fast). This strategy may increase some of the important adaptive responses to exercise. Therefore, on some occasions, an athlete may deliberately choose not to consume carbohydrate during the session or during the first part of a session¹².

1. Peake JM, Neubauer O, Walsh NP, Simpson RJ. (2017). Recovery of the immune system after exercise. J Appl Physiol 122(5), 1077-1087.
2. Sale C, Varley I, Jones TW, James RM, Tang JC, Fraser WD, Greeves JP. (2015). Effect of carbohydrate feeding on the bone metabolic response to running. J Appl Physiol. 119(7), 824-30.
3. Pfeiffer B1, Stellingwerff T, Zaltas E, Jeukendrup AE. (2010). Oxidation of solid versus liquid CHO sources during exercise. Med Sci Sports Exerc. 42(11), 2030-7.
4. Phillips SM, Sproule J, Turner AP. (2011). Carbohydrate ingestion during team games exercise: current knowledge and areas for future investigation. Sports Med, 41(7), 559-85.
5. Stellingwerff T, Cox GR. (2014). Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab, 39(9), 998-1011
6. Burke LM, Maughan RJ. (2015). The Governor has a sweet tooth - mouth sensing of nutrients to enhance sports performance. Eur J Sport Sci, 15(1), 29-40
7. Costa RJS, Miall A, Khoo A, Rauch C, Snipe R, Camões-Costa V, Gibson P. (2017). Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Appl Physiol Nutr Metab, 42(5), 547-557.
8. Miall A, Khoo A, Rauch C, Snipe RMJ, Camões-Costa VL, Gibson PR, Costa RJS. (2018). Two weeks of repetitive gut- challenge reduce exercise-associated gastrointestinal symptoms and malabsorption. Scand J Med Sci Sports, 28(2), 630-640.
9. Jeukendrup AE. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Curr Opin Clin Nutr Metab Care, 13(4), 452-457.
10. Burke LM, Hawley JA, Wong SH, Jeukendrup AE. (2011). Carbohydrates for training and competition. J Sports Sci, 8, 1-11.
11. Needleman I, Ashley P, Fairbrother T, Fine P, Gallagher J, Kings D, Maugha RJ, Melin AK, Naylor M. (2018). Nutrition and oral health in sport: time for action. Br J Sports Med, 52(23), 1483-1484.
12. Bartlett JD, Hawley JA, Morton JP. (2015). Carbohydrate availability and exercise training adaptation: too much of a good thing? Eur J Sport Sci, 15(1), 3-12.

• Electrolyte replacement supplements are powders, tablets or ready to drink products designed for replacement of fluid and electrolytes (in particular, sodium and potassium) lost through sweat or other body fluids. Typical uses include:
  • As a method of increasing total body water and plasma volume prior to exercise in hot environments, when opportunities for fluid replacement are inadequate to prevent significant fluid losses (pre-exercise hyperhydration).
  • As an alternative to standard sports drinks when it is deemed of value to replace large electrolyte losses during and after exercise with a more aggressive approach, or where electrolyte replacement is desired with limited or no carbohydrate intake.
  • To restore fluid/electrolyte deficits caused by other factors such as the dehydration techniques undertaken to “make weight” for competition or gastrointestinal upsets (vomiting/diarrhea etc.).
• Guidelines around the need, or optimal plan, for sodium intake during endurance (i.e. > 1 hour) and ultra-endurance exercise (i.e. >4 h) are unclear.
  • General recommendations include 0.5–0.7 g per litre of fluid (21–30 mmol/L)¹ with this target being set as a balance between preserving thirst drive and preserving the palatability of fluids.
  • There are suggestions that in situations of large sweat sodium losses (e.g. ultra-endurance exercise, individuals who have “salty” sweat or combination of these factors) a more proactive approach to sodium intake during exercise may be needed. However, the best method for assessing these needs, and planning for sodium replacement, are yet to be determined.
• Two contentious issues around electrolyte/sodium replacement during exercise concern the prevention of cramps and hyponatremia.
• Exercise associated muscle cramps may be caused by multiple factors, with primary risk factors including fatigue due to unaccustomed volume/intensity of exercise and previous history of cramps. There is some evidence, although controversial² that whole body sodium depletion may be a cause of specific types of cramps in some individuals. Electrolyte supplementation may be beneficial in these athletes.³ There is also some suggestion that a sudden drop in plasma sodium concentration (e.g. dilution due to large, sudden intake of plain water) may increase susceptibility to muscle cramps, although the exact mechanism underlying this effect has not yet been determined.⁴
• Typically, plasma sodium concentrations are typically tightly regulated at ~ 135–145 mmol/L and athletes become mildly hypernatremic (high blood sodium concentrations) during exercise because sweat losses deplete fluid stores at a higher rate than sodium/electrolyte losses (sweat is hypotonic compared with blood).
  • Mild hyponatremia (<135 mmol/L) can occur in some sports, often without overt symptoms, due to the strategies used to replace sweat fluid and sodium losses. An athlete can dilute blood sodium concentrations during exercise by drinking fluids at a rate that is slightly greater than their sweat losses, or by replacing large sweat losses (and the accompanying large electrolyte loss) with low sodium fluids (e.g. water or soft drinks). Sodium replacement during exercise can address this issue provided the total fluid consumed remains less than sweat losses. Whilst mild hyponatremia is usually asymptomatic, a large and sudden drop in blood sodium concentration, even when the final value remains > 130 mmol/L, can result in symptoms of severe hyponatremia (below), due to the rapid shift of water into the intracellular space (Hew Butler et al. 2015).
  • Severe hyponatremia (plasma sodium < 130 mmol/L) can be associated with confusion, nausea, headaches, and the potentially fatal outcome of cerebral oedema. It is comparatively rare in sport and occurs when an athlete consumes fluid at a rate that is substantially higher than actual sweat losses, and the rate of urine production. This condition may be exacerbated in individuals/scenarios involving inappropriate secretion of the renal hormone ADH (also known as vasopressin) which reduce urine production (vasopressin or ADH). Although sodium replacement in concert with “over drinking” behaviour may slightly reduce the degree to which hyponatremia develops, the underpinning cause of severe hyponatremia is excessive fluid intake and should be tackled directly.⁵
  • Rehydration after exercise (or other dehydrating events) requires the replacement of electrolyte losses before fluid balance can be fully restored. In the absence of electrolyte replacement, fluid replacement will restore blood osmolarity (concentration) before it has replaced its volume, leading to a reduction in thirst and increased urination. Such signs can be confused with adequate or overhydration. Rehydration after the development of moderate-severe dehydration (e.g. fluid loss > loss of 2% BM) is more efficient when there is a considered replacement of electrolytes. Although sodium can be replaced by eating salty foods (e.g. bread, breakfast cereal, cheese & crackers, Vegemite^TM) or adding salt to meals, electrolyte supplements or sports drinks with higher sodium content can be useful for rapidly restoring fluids and electrolytes with a more targeted approach, especially if food intake is likely to be minimal or delayed after exercise. See Table 1 for details on higher sodium foods.

• Pharmaceutical Oral Rehydration Solutions (ORS) and sports-related Electrolyte Replacement Supplements are available in ready to drink, tablet, ice block and powdered forms in a wide variety of flavours.
  • In general, ORS are manufactured according to the World Health Organisation guidelines for the treatment and prevention of dehydration associated with diarrhoea and gastroenteritis. Typical sodium content is in the range of 50-60mmol/L which is ideal for electrolyte and fluid replacement following large losses. Note that sweat sodium concentrations are often less than this value, and therefore exclusive reliance on high sodium ORS products with no plain water intake during ultra-endurance exercise could result in increased blood sodium concentration, due to replacing proportionally more sodium than fluid. -
  • Since ORS are focused on electrolyte/fluid replacement; the low-moderate carbohydrate content (1.5-2% or 1.5-2 g/100 ml) is present to contribute to intestinal sodium/fluid absorption rather than achieve typical fuelling goals for exercise.
• Sports-related electrolyte supplements which are marketed to athletes include:
  • Electrolyte-only powders and tablets which can be added to fluids varying in carbohydrate content according to the athlete’s needs.
  • Sport drinks with high electrolyte concentrations (often marketed as an “endurance formula” which provide higher amounts of both carbohydrates and electrolytes. The sodium content of these drinks is typically within the range of 30-50 mmol/L (in contrast to typical ranges of 10-30 mmol/L in standard sports drinks)

Note that the characteristics of sports drinks are discussed in a separate Sports Drinks (Carbohydrate-Electrolyte drinks) fact sheet)

Table 1: A sodium ready reckoner of common high sodium foods

Food First approach - The following meals provide ~60mmol of sodium (the equivalent to 1litre of an ORS) as well as other important nutrients. -

• Vegemite and cheese on toast ^{C P Ca}: 2 slices white bread + 2 slices cheese + 1 teaspoon vegemite
• Baked beans on toast ^{C P}: 2 slices white bread + ½ 220g tin
• Ham, cheese & pickle sandwiches ^{C P Ca}: 2 slices white bread + 1 slice cheese + 1 tablespoon pickle spread
• Smoked salmon & olive salad ^{C P I}: 1 slice smoked salmon + 5 olives
• Cheese, crackers & pretzels ^{C P Ca}: 1 cup pretzels + 3 slices cheese + 2 rows of rice crackers
• Cereal & toast ^{C P Ca}: 1 ½ cups cornflakes + 1 ½ cups milk + 2 x toast + 1 Tablespoon peanut butter
• Tuna, cheese & salad wrap + nuts ^{C P Ca} I: 1 wrap + 1 x 90g tin tuna + 1 slice cheese + salad + 1 teaspoon butter + 1/3 cup peanuts

^C provides valuable amounts of carbohydrate to support post-exercise refuelling

^P provides valuable amounts of protein to support post-exercise repair

^I provides valuable amounts of iron to support overall athlete health and performance

^Ca provides valuable amounts of calcium to support overall athlete health and performance

• Before exercise in hot environments, where large sweat losses cannot be practically replaced: Pre-exercise hyperhydration can be achieved by consuming up to 10mL/kg body weight of fluid with a very high sodium concentration, ideally as close to plasma sodium concentration (i.e. 135mmol/L) as tolerated, within 1-2 hours prior to exercise. This concentration, as much as double that of typical ORS products, can be achieved by manipulating the ratio of product to water, or using commercially available products designed specifically for this purpose. Note that other strategies (i.e. glycerol supplementation) can also be used for pre-exercise hyperhydration.
• During exercise and sporting activities: Electrolyte replacement supplements may be useful in the following situations:
  • When targeted replacement of large sodium losses is desired. This may occur in events or individuals where there is a high rate of sweat loss, prolonged duration of sweating, or evidence of “salty sweat” (high sweat content of electrolytes). A personalised fluid plan should be made with the help of a Sports Dietitian; it is also noted that during ultra-endurance events, sodium replacement may also be achieved via food choices.
  • When electrolyte replacement is desired without an accompanying carbohydrate intake (e.g. undertaking training with ‘low carbohydrate availability” or exercise undertaken during a period of reduced energy intake).
• For the prevention and treatment of dehydration during diarrhoea and gastro-enteritis, particularly as guided by a Sports Physician. Note that ORS are recommended for these purposes since the priority is to rehydrate rather than consume energy/carbohydrate.
• In the restoration of moderate-large fluid deficits incurred during exercise or other dehydrating activities (e.g. “making weight”), where a targeted replacement of fluid and electrolyte losses will assist with more rapid and effective rehydration. Scenarios in which this might be useful include a short period of recovery until an exercise session, or after an exercise session late in the day where the athlete wants to rehydrate with minimal risk of sleep disturbances due to the need for a toilet break.

The athlete with a moderate-large fluid deficit should follow a rehydration plan tailored to meet their estimated fluid loss. Specifically:

• The athlete should consume a volume of fluid equal to ~ 1.2–1.5 times their estimated fluid deficit within 2-4 hours following the dehydrating activity, or as much of this volume as can be comfortably tolerated.
• Fluid intake should be accompanied by electrolyte replacement (particularly sodium) to optimise fluid retention. This may be achieved through food sources, via the salting of meals, or through the use of higher sodium sports drinks or electrolyte supplements, according to what is most practical. While intake of food sources can target other nutrition goals, it is noted that electrolyte supplements provide a known sodium content that may be more precisely achieved.
• Since the carbohydrate content of ORS and some sports electrolyte supplements is negligible, refuelling goals may need to be addressed separately

Unnecessary expense and unclear guidelines

There is currently no consensus regarding the value of sodium replacement during exercise for either performance or health reasons.

Disruption to hydration plan if used incorrectly

• Increasing the sodium content of a drink generally reduces the drink palatability and may interfere with the voluntary consumption of fluid.
• Excessive intake of salt supplementation during exercise may cause gastrointestinal problems or further impairment of fluid balance.

Failure to address major risk for hyponatremia during exercise

Excessive fluid intake during exercise (substantially greater than sweat losses) is the major cause of serious cases of hyponatremia in susceptible people. Sodium replacement during exercise does not address this problem and may provide a false sense of security.

Consideration of larger messages about salt and health

The Dietary Guidelines for Australians promote a reduction in sodium/salt intake by the community, due to the link between salt intake and hypertension in susceptible people. Electrolyte replacement during and after sport may be considered as a special situation for a specific sub-group of the population, however, general guidelines for healthy eating should not be overlooked.

1. Sawka M, Burke L, Eichner R, Maughan R, Montain S, Stachenfeld N. (2007). Exercise and Fluid Replacement. Position Stand. Med Sci Sports Exerc, 39, 377- 390.
2. Schwellnus MP. (2009). Cause of exercise associated muscle cramps (EAMC) - altered neuromuscular control, dehydration or electrolyte depletion? B J Sports Med, 43, 401-408.
3. Bergeron M. (2007). Exertional heat cramps: Recovery and return to play. J Sport Rehabil, 16, 190-196.
4. McCubbin A, Allanson B, Caldwell Odgers J, Cort M, Costa R, Cox G, Crawshay S, Desbrow B, Freney E, Gaskell S, Hughes D, Irwin C, Jay O, Lalor B, Ross M, Shaw G, Périard J, Burke L. (2020). Sports Dietitians Australia Position Statement: Nutrition for Exercise in Hot Environments. Int J Sport Nutr Exer Metab, 30, 83-98.
5. Hew-Butler T, Rosner MH, Fowkes-Godek S, Dugas JP, Hoffman MD, Lewis DP, et al. (2015). Statement of the 3rd International Exercise-Associated Hyponatremia Consensus Development Conference, B J Sports Med, 49 (22), 1432-46.

Protein occurs in all living cells and has both functional and structural properties, accounting for ~15-20% of total body mass. Approximately half of the body’s protein is present as skeletal muscle, but protein is also an important building block of other tissues, including bone, cartilage, skin and blood as well as functional molecules such as enzymes and hormones. Each protein is made up of a special combination of amino acid building blocks.

Protein has been a nutrient of great interest and debate in the world of sports nutrition for many decades. Its role in facilitating muscle building and repair has made it an obvious focus of attention by athletes and coaches. Within scientific circles, there has been lively discussion about the protein requirements of athletes and others committed to daily exercise. This has finally been resolved with the following findings.

• Daily requirements for protein are increased due to a regular commitment to exercise and to support the synthesis of new proteins that accompanies the adaptive response to each workout or event. Indeed, the protein targets for athletes in heavy training are in the range of 1.2-1.6 g/kg body mass daily¹, which is up to double the amount recommended for sedentary populations.
• These recommendations apply equally to endurance, team and strength/power athletes since high level exercise promotes a specific increase in different proteins according to the stimulus of the exercise session.
• Protein targets are now set-in terms of the spread of protein over the day rather than the total protein target, since optimal protein synthesis occurs for at least 24 hours after exercise. Athletes are encouraged to include a small serve of protein rich foods at 3-5 eating occasions each day. For example, three main meals, a post-training snack and a pre-bed or mid-meal snack. Targets of 0.3-0.4 g/kg typically equate to 15-30 g of protein at each meal or snack.
• The highest recommendations for protein (1.6-2.4 g/kg body mass daily) are targeted to athletes who are undertaking weight loss programs. Such athletes usually desire to achieve “high quality weight loss” in which they reduce fat mass but retain muscle mass.²

Protein foods are widely found in the Australian diet and Western eating patterns. Indeed, most athletes easily achieve total daily protein intake targets, even without considering protein supplementation. However, to optimise dietary protein intake, consideration should be given to the quality of protein food choices, and the timing and distribution of protein intake throughout the day.³

Proteins are found in both animal and plant foods with the major sources in the Australian diet being meat, fish and poultry (32%), cereals and cereal-based foods (26%), plus dairy foods (20%).⁴ Since the amino acid profile of animal proteins is closer to that of humans, they are generally considered to be of higher biological value (HBV). Such protein sources typically provide higher amounts of all the essential amino acids, including leucine, which is the amino acid primarily responsible for turning on protein metabolism. Plant based proteins generally have lower digestibility and lower amounts of essential amino acids. However, any negative implications of this may potentially be overcome by simply increasing total protein intake, using an array of plant-based protein sources (e.g. cereal proteins and legumes) to complement their amino acid profiles and/ or blending plant and animal-based proteins sources at a meal.⁵

• Protein supplements are among the most popular, available and steadily increasing supplement products, with projections of a world-wide market value of $US21.5 billion by 2025. Sports nutrition is the major application for protein supplements and the fastest growing sector is plant protein supplements.
• Protein supplements are available as stand-alone products in the form of powders, bars and ready to drink shakes. More recently, there has been a trend for the fortification of commercial foods with protein isolates (e.g. breakfast cereals, food bars). A range of different forms and sources of protein supplements is found (see Table on next page).

Protein supplements can be broadly classified according to their nutrient profile as either providing protein only (as a single protein source or a protein blend) or with the targeted addition of other ingredients.

• Carbohydrate: found in multi-purpose mixed-macronutrient or recovery products targeting refuelling as well as protein support.
• Fat: added to ‘weight gain’ or ‘bulking’ formulas in order to provide a high kilojoule supplement for those with increase energy needs. -
  • Note that products with such profiles have a diluted protein content in comparison to protein supplements, as well as a reduced micronutrient content compared to food.
  • See fact sheet on mixed macronutrient supplements.
• Individual amino acids including branched chain amino acids, leucine, glutamine etc. May be valuable in fortifying the lower leucine content of plant protein supplements but unnecessary in animal protein sources or as an isolated supplement themselves.
• Evidence based performance ingredients (creatine, caffeine, beta alanine etc). Although these ingredients may have proven value in sports nutrition, benefits are specific to the scenarios and protocols of use. The doses provided in protein powders may not be optimal or able to be used correctly. It is preferable for such ingredients to be sourced as individual products so that the athlete retains control over when and how they are used.
• Other ingredients. Some protein powders contain ingredients with minimal evidence of benefits, including some that are likely to be harmful or banned in sport. In general, multi-ingredient products of this nature should be avoided since they are unnecessarily expensive and increase the potential for inadvertent doping/contamination.

• The decision to use a protein supplement should only come after consideration of several factors including the athlete’s training load and goals, lifestyle commitments, daily energy requirements, existing meal plan, practicalities of post-exercise scenarios, and available finances.
• A ‘food first’ policy should apply to all supplements, but especially to protein needs, because of the array of high biological value protein-rich foods that are available in most environments. Many of these food choices are able to meet multiple sports nutrition goals and nutrient targets. Nevertheless, well-considered uses of protein supplements may include:
  • When the delivery of rapidly digested proteins is a priority, such as in the period immediately after key workouts
  • As a means of fortifying existing meals or snacks which are traditionally low in protein (e.g. breakfast or pre-bed snack)
  • As an alternative to whole foods and bulky meals when appetite is poor.
  • When the facilities to store or prepare a food form of protein are not available, or the quality and accessibility of protein-rich foods in the local environment are limited (e.g. travel to locations with questionable food safety or contamination issues
  • During specialised weight loss programs where a higher protein intake within an energy-restricted diet is required to optimise the retention/ increase in lean mass
• Depending on the athlete’s size, energy requirements and other nutrition goals, it is likely that a dedicated supplement providing a 20-40 g protein per serve will meet the needs of most situations in sports nutrition.
• The potential for protein supplements to be used in conjunction with whole foods to boost the total content of a meal or snack (e.g. an ingredient in a smoothie, or a cereal bowl) should be considered in view of expense, overall nutrient intake and overall “food first” principles.

Unnecessary expense

Although protein is an important part of most eating occasions, this does not necessitate the use of protein supplements. A “food first” approach can often identify suitable protein-rich foods and drinks to meet the targets and practical considerations for each meal/snack. Even when the convenience of a protein supplement warrants its considered use, the athlete can minimise the cost by choosing the simplest product (i.e. a concentrate or isolate) rather than more expensive brands based on hydrolysates or containing extra (unnecessary) ingredients. Another cost-saving strategy is to use the protein supplement as an ingredient that enhances a meal or snack rather than a stand-alone product.

Effect on overall nutrient intake and nutrition goals

It can be easy to become reliant on supplements to meet protein intake targets without realising the differences between foods and supplements. Most protein-rich foods provide a range of other important nutrients to our diets (e.g. calcium, iron, zinc, vitamins and essential fatty acids) and overreliance on protein supplements can reduce the athlete’s ability to achieve overall nutrient needs. The use of compact protein forms such as drinks and bars may allow an athlete with high-energy needs to eat more than their appetite would typically allow. While this is useful in some scenarios (e.g. post-exercise, during periods of growth or targeted weight gain), it may not be a helpful strategy for all athletes or scenarios.

Unnecessary and harmful ingredients

Some protein powders contain unnecessary ingredients, including products that are harmful or banned. A recent consumer report from the USA6 conducted independent testing of popular protein supplements and noted that many contained detectable levels of contaminants such as heavy metals (e.g. lead, cadmium, mercury, arsenic) and BPA (a toxic by-product of plastics manufacture). While this survey has been criticised due to the lack of peer review, it is a reminder that foods absorb such contaminants from their growth environment and/or during the manufacturing process; these are magnified in the case of concentrated supplements. In general, it is recommended that consumption of protein supplements be limited to 1-2 serves a day and that third party, batch tested protein supplements be sourced. That said, batch testing confirms the absence of WADA banned substances, not other contaminants like heavy metals.

Allergy risk

Protein products may contain tree nuts, milk, soy and other allergens that some athletes may need to avoid.

1. Phillips SM, Chevalier S, Leidy HJ. (2016). Protein requirements beyond the RDA: Implications for optimising health. Appl Physiol Nutr Metab, 41, 565-72.

2. Hector AJ, Phillips SM. (2018). Protein recommendations for weight loss in elite athletes: A focus on body composition and performance. Int J Sport Nutr Exerc Metab, 28, 170-177.

3. Phillips SM, van Loon LJ. (2011). Dietary protein for athletes: From requirements to optimum adaptation. J. Sports Sci, 29, 29-38.

4. Gillen JB, Trommelen J, Wardenaar FC, Brinkmans NYJ, Versteegen JJ, Jonvik KL, Kapp C, de Vries J, van der Borne JJGC, Gibala MJ, van Loon LJC. (2017). Dietary protein intake and distribution patterns of well-trained Dutch athletes. Int J Sport Nutr Exerc Metab, 26, 105-114.

5. Berrazaga I, Micard V, Gueugneau M, Walrand S. (2019). The role of the anabolic properties of plant versus animal-based protein sources in supporting muscle mass maintenance: A critical review. Nutrients, 11, 1825.

6. Clean Label Project 2018 survey of Protein Powders: https://www.cleanlabelproject.org/protein-powder/

Mixed macronutrient supplements provide a compact and practical source of variable amounts of protein and carbohydrate, plus micronutrients, for use in situations where it may be impractical to eat, or access, whole foods or when appetite is suppressed. This typically occurs around exercise.

• A range of mixed macronutrient supplements are available in the form of powders, bars/ balls and ready to drink (RTD) shakes. They can vary markedly in their macronutrient composition, from carbohydrate-based products with a small amount of protein, to those which are rich in protein but intentionally lower in carbohydrate.
• Some mixed macronutrient supplements are fortified with micronutrients, typically containing 25-50% of the Nutrient Reference Values (NRV) of various vitamins and minerals per serve, while others may also include proposed ‘performance enhancing’ ingredients (creatine, BCAA’s, carnitine etc.). In this role, they provide a convenient portable and non-perishable snack with a potentially valuable macronutrient and micronutrient content.
• The specific composition of mixed macronutrient supplements can vary markedly. The form and composition of the product will influence their appropriate use by athletes (Table 1).

Table 1. Varieties of mixed macronutrient supplements

Note: Some mixed macronutrient products do not fit precisely into one of the above categories: this is particularly the case for bars that are much larger or smaller than the typical 50-60 g product. Larger bars (>90g) can often be divided in half, or 2 smaller bars may be consumed to provide similar nutrient profiles to those listed in this table.

• Mixed macronutrient supplements can be used in a variety of situations as a short-term replacement of whole foods. A range of common uses and appropriate scenarios is provided below; it is noted that the macronutrient supplement may achieve a number of these goals simultaneously.
• To provide a convenient source of carbohydrate to support fuelling and/ or recovery goals before, during or after exercise.
  • A  pre-exercise snack for athletes who experience pre-event nervousness with accompanying loss of appetite or reduced gut function or who need to eat immediately before an exercise session (e.g. early morning training).
  • Intake during prolonged exercise (e.g. ultra-endurance events) conducted at moderate intensities over many hours or days, to reduce flavour fatigue by providing a greater range of tastes and textures or to provide the benefits from consuming protein and other nutrients.
  • (note that there is a separate fact sheet on sports/energy bars with additional information on this theme)
• To provide a convenient source of protein and energy when whole foods are not available or practical to consume.
  • A post-exercise recovery option to stimulate protein synthesis and adaptation, for athletes who have suppressed appetite or an inability to store or prepare whole foods for immediate intake.
  • An addition to a meal or snack to boost energy and protein intake towards sports nutrition goals when the residual choices fail to do this or when the environment does not allow the athlete to store or prepare their own meals/snacks.
  • When training/competing in a foreign country and the food supply/food safety (hygiene) is questionable.
  • (see separate fact sheet on isolated protein supplements with additional information on this theme)
• To provide a compact, portable and less filling source of extra energy and protein between meals.
  • A convenient and nutrient-dense energy boost for adolescents undergoing a growth spurt, athletes undertaking heavy training loads or during periods of lean mass gain, especially when appetite is insufficient to drive the intake of required food amounts.
• To provide a low fibre/residue source of energy and nutrients when it is useful to manipulate body mass and bowel contents in the day(s) before competition.¹
  • In weight category sports, to replace the food weight and fibre content of normal meals and foods with a compact and lightweight source of key nutrients over the day(s) prior to weigh-in. This may allow a small but potentially important reduction in body mass prior to the weigh-in without compromising nutritional status/goals.
  • In endurance sports (e.g. running, cycling), to reduce gut contents in the day(s) prior to the race to enhance performance by reducing the risk of gastrointestinal disturbances. The small reduction in the mass of gut contents may counteract the weight gain associated with glycogen loading and/or provide a small performance advantage in its own right.

Unnecessary expense

Sports foods such as mixed macronutrient supplements are not needed at every training session or in the everyday diet and may be an unnecessary expense. In general, the use of whole foods to meet fuelling and recovery goals will be more cost-effective and provide a wider range of important nutrients.

Unnecessary energy intake or poor handling of weight management goals Athletes need to consider their physique and broarder nutritional goals when deciding whether to consume energy-dense mixed macronutrient supplements. In the case of athletes who have short- or long-term restrictions on dietary energy intake, overuse of energy dense, low satiety products such as shakes and sports bars may create problems with energy balance and overall nutrient density of the diet.2 In such cases, the athlete should focus on using whole foods with higher satiety scores for their sports nutrition goals or should arrange their training/eating timetables so that an existing meal or snack fulfils their recovery goals.

Athletes should always seek the advice of a Sports Dietitian before undertaking any low residue eating strategies to promote acute weight loss. Weight management for athletes in weight category sports requires a wholistic approach to weight management, both acutely and chronically, with due consideration also given to recovery strategies post weigh-in.

Gut discomfort

• Although most athletes tolerate mixed macronutrient supplements well, small number of athletes will suffer from significant gastrointestinal issues and may need an individualised protocol. High protein, low carbohydrate bars may be a particular concern, given their reliance on sugar alcohols to promote flavour and retention of moisture while also moderating refined carbohydrate intake.
• Individuals with fructose malabsorption or FODMAP intolerance should also be aware of the fructose content of mixed macronutrient supplements containing multiple transportable carbohydrates.

Allergy risk

Mixed macronutrient supplements may contain tree nuts, milk and gluten (from wheat flour, oats and barley) and may need to be avoided by individual athletes who have allergies to any of these items.

1. Reale et al. (2017). Acute-weight-loss strategies for combat sports and applications to Olympic success. Int J Sports Physiol Perf, 12, 142-51.
2. Mouroa et al. (2007). Effects of food form on appetite & energy intake in lean & obese young adults. Int J Obesity, 31, 1688-95.

• Iron is a fundamental mineral involved in energy metabolism, oxygen transport, cognitive function and immunity.
• Almost two-thirds of the body’s iron is found in haemoglobin in circulating erythrocytes, with smaller amounts in ferritin and myoglobin.
• The body cannot produce its own source of iron and therefore it relies on absorbing the iron we consume as part of our diet or supplements. The recommended daily intakes of iron for adults are:
  • ♂ - 8 mg per day
  • ♀ - 18 mg per day (pre-menopause)
• Athletes are more susceptible to iron deficiency due to the greater iron demand associated with exercise, and the finite opportunity they have to replenish stores from food sources. Some high-risk athlete populations include:

1. Female athletes (due to additional iron lost during menses).
2. Endurance athletes, including those training at altitude (perhaps due to the greater demand on oxygen transport mechanisms).
3. Vegetarian and Vegan athletes (since less iron is absorbed from plant sources).
4. Athletes in Low Energy Availability.

• Compromised iron levels are typically associated with symptoms of lethargy and fatigue. In athletes, it may also manifest in reduced training and performance outcomes or a suppressed ability to respond/adapt to training stimuli.
• Iron deficiency is an issue that progresses in severity because of a negative iron balance. Early stages, known as iron deficiency non-anaemia (IDNA), occur when ferritin stores are depleted without significant impact on haemoglobin concentrations. The most severe stage, iron deficiency anaemia (IDA), presents when both iron stores and haemoglobin are depleted.

• Treatments for an iron deficiency range from nutritional support, oral iron supplementation, and intravenous iron approaches, depending on the severity of the issue and the athlete patient history. Increasing dietary iron intake is the initial and most conservative treatment for iron deficiency. Some examples of haem (animal derived) and non-haem (plant derived) sources of dietary iron.¹
• Oral iron supplements are the following avenue of treatment and are typically provided as ferrous salts: ferrous fumarate, ferrous sulphate or ferrous gluconate.
• Ferrous sulphate preparations (e.g. FerroGrad^®) containing ~100 mg elemental iron are the established and standard treatment for depleted iron stores. The total amount of elemental iron contained in the supplement should be checked to ensure that the specific target dose is achieved.
• Controlled-release iron formulations (e.g. Maltofer^®) may be used if ferrous salts are not well tolerated by the athlete.
• Intravenous iron should only be considered in consultation with a sports physician. The efficacy of this approach appears best when IDA is present – i.e. when both ferritin stores and haemoglobin are compromised.

• Physicians are guided by the following outline when considering the frequency of iron blood screening for athletes.²
• Early identification of compromised iron stores (in the IDNA phase) is important since it allows athletes to consider nutritional and supplementation options with their physician and/ or accredited sports dietitian to prevent progression to IDA.

Figure 1. Framework of considerations for the frequency of iron blood screening in athlete populations.

Image text

Considerations and frequency of iron blood screening for athletes

Variables to be considered.

• Minimum: serum ferritin, hemoglobin concentration, transferrin saturation.
• Desirable: Serum soluble transferrin receptor, hemoglobin mass, C-reactive protein.

Standardisation of blood collection.

• Time of day: Preferably in the morning.
• Hydration state: Hydrated preferably assessed by waking urinary specific gravity (<1.025).
• Low to moderate activity in the proceeding 24 hours, including no muscle-damaging exercise (e.g. eccentric) in 2-3 days prior.
• No signs of sickness or infection.

Annually

• No history of iron deficiency.
• No history of irregular/excessive menses or amenorrhea.
• No reports of fatigue after extended rest.
• Strength/power-based sports with minimal endurance component.
• No iron-related dietary restrictions.
• No evidence of low energy availability.
• No intention to undertake hypoxic training in the next 12 months.
• No underlying pathology (e.g. coeliac or Crohn’s disease).

Biannually

• Female.
• Previous history (≥24 months) of iron depletion (e.g. Stage 1).
• Previous history (≥24 months) of irregular/excessive menses.
• Intention to undertake high training loads especially in endurance and team-based sports.
• Minimal (or zero) reports of prolonged fatigue after extended rest.
• No iron-related dietary restrictions (e.g. non-vegetarian, non-vegan).
• No evidence of low energy availability.
• Intention to undertake hypoxic training in the next 12 months.

Quarterly

• Any recent history (<24 months) of iron depletion/deficiency (Stage 1, 2, or 3) irrespective of sex.
• Any evidence of irregular/excessive menses or amenorrhea.
• High training loads in endurance and team-based sports.
• Reporting prolonged fatigue/lethargy even after extended rest.
• Reduced work capacity during training.
• Unexplained poor athletic performance.
• Individuals restricting sources of dietary iron (e.g. vegetarian and vegan) or overall caloric intake.
• Any evidence of low energy availability.
• Intention to undertake hypoxic training in the next 6 months.

This figure has been adapted from Sim et. al.²

• Below is a framework to guide practitioners towards optimal treatment protocols for iron deficient athletes, diagnosed via haematological indices.¹
• Iron supplements should only be taken under medical supervision as part of an integrated iron management program, which includes dietary assessment and enhancement of dietary iron intake.
• Current research suggests that a daily dose of 100 mg of elemental iron (or every second day if GI upset is present) for 8-12 weeks can significantly improve ferritin stores.^3,4,5 This should be confirmed via a subsequent blood test.
• Consuming the oral iron supplement in the morning, as close to exercise as possible, may result in a greater level of iron absorption.⁶

Figure 2. Framework to guide practitioners towards optimal treatment protocols for iron deficient athletes, diagnosed via haematological indice

Image text

Athlete blood screening

[left hand side]

IDNA

• sFer <35 µg·L^-1·
• [female symbol] [Hb] 120 – 155 g·L^-1·
• [male symbol] [Hb] 135 – 175 g·L^-1·

Oral iron supplementation (4-12 weeks)

1. 100 mg oral iron (ferrous salt) daily in the morning
   If negative GI side-effects experienced
2. 100 mg oral iron (ferrous salt) on alternate mornings
   If negative GI side-effects persist
3. 60 mg (or tolerable dose) oral iron on alternate mornings

OR

100. mg controlled release oral iron on alternate mornings

Athlete intolerant or not responding to oral iron treatment

[middle]

Dietary assessment/intervention with an accredited sports dietitian

[right]

IDA

• sFer <12 µg·L^-1·
• [female symbol] [Hb] <120 g·L^-1·
• [male symbol] [Hb] <135 g·L^-1·

IV treatment

Note: Individual responses to IV treatment vary. Follow up blood screen at 1 & 6-months post-treatment recommended.

[key]

Key

- - - Medical professional’s discretion

This figure has been adapted from McCormick et. al.¹

• The absorption of oral iron supplements is enhanced by consuming it with a source of vitamin C (~50-100 mg). This can be achieved by choosing a supplement in which Vitamin C is also provided, or by consuming it with an appropriate (e.g. citrus) fruit or juice. Factors that interfere with iron absorption such as calcium (dairy) and tannins (tea and coffee) should be avoided for an hour each side of the time of consumption of the supplement.
• Examples of both inhibitors and promoters of non-haem iron absorption¹ are presented in Table 1

Table 1. Dietary factors that either enhance or inhibit iron absorption.

• If an athlete is undertaking specific altitude training, a pre-training screen of iron status is advised. This should be done with enough time (i.e. 8-12 weeks prior) to allow correction of iron depletion (IDNA or IDA) to be achieved prior to the start of the altitude training program.
• Athletes who have ferritin levels of 50-100 μg·L-1 (i.e. just above the levels traditionally considered to represent iron depletion) might consider taking an oral iron supplement (~100 mg daily or alternate day, as above) for two weeks prior to the start of altitude training and throughout the training program, since there is evidence that this supports greater adaptation to the altitude stimulus. Note: IV iron supplementation does not appear to improve the benefits of altitude adaptation more than oral supplementation.^4,7,8

Failure to address dietary issues or other underlying causes of the iron deficiency

• Iron supplementation does not address dietary issues. Dietary counselling in the early investigation phase of treatment should be provided via a referral to an accredited sports dietitian.
• Where possible, the underlying cause for iron deficiency should be established so that it can be addressed. In some circumstances, a medical issue may need to be corrected.

Risk of iron overload or other medical issues

• Excessive iron intake in some athletes may lead to iron overload. People with haemochromatosis should avoid iron supplementation, since extremely high iron levels can be toxic to the body’s organs. Further information can be obtained from a sports doctor.
• Intravenous and intramuscular iron supplementation carries a risk of anaphylactic shock, and problems due to the use of needles.

Risk of gastrointestinal upset

• Some oral iron preparations cause gastrointestinal upset including constipation. Supplementation strategies such as ‘every second day’ approaches have been shown to reduce this gastrointestinal response, without compromising the supplements efficacy⁵ over time (8-12 weeks).

1. McCormick R, Sim M, Dawson B, Peeling P. (2020). Refining treatment strategies for iron deficient athletes. Sports Med, 50(12), 2111-2123.
2. Sim M, Garvican-Lewis LA, Cox GR, Govus A, McKay AKA, Stellingwerff T, Peeling P. (2019). Iron considerations for the athlete: a narrative review. Eur J Appl Physiol, 119(7), 1463-1478.
3. Dawson B, Goodman C, Blee T, Claydon G, Peeling P, Beilby J, Prins A. (2006). Iron supplementation: oral tablets versus intramuscular injection. Int J Sport Nutr Exerc Metab, 16(2), 180-6.
4. Garvican LA, Saunders PU, Cardoso T, Macdougall IC, Lobigs LM, Fazakerley R, Fallon KE, Anderson B, Anson JM, Thompson KG, Gore CJ. (2014). Intravenous iron supplementation in distance runners with low or suboptimal ferritin. Med Sci Sports Exerc, 46(2), 376-85.
5. McCormick R, Dreyer A, Lester L, Sim M, Goodman C, Dawson B, Peeling P. (2019a). The efficacy of daily and alternate day oral iron supplementation in iron depleted athletes. Unpublished data.
6. McCormick R, Moretti D, McKay AKA, Laarakkers CM, Vanswelm R, Trinder D, Cox GR, Zimmerman MB, Sim M, Goodman C, Dawson B, Peeling P. (2019b). The Impact of Morning versus Afternoon Exercise on Iron Absorption in Athletes. Med Sci Sports Exerc, 51(10), 2147-2155.
7. Garvican-Lewis LA, Govus AD, Peeling P, Abbiss CR, Gore CJ. (2016). Iron Supplementation and Altitude: Decision Making Using a Regression Tree. J Sports Sci Med, 15(1), 204–205.
8. Govus AD, Garvican-Lewis LA, Abbiss CR, Peeling P, Gore CJ. (2015). Pre-Altitude Serum Ferritin Levels and Daily Oral Iron Supplement Dose Mediate Iron Parameter and Hemoglobin Mass Responses to Altitude Exposure. PLoS One, 10(8).

• Vitamins and minerals are necessary for a broad range of essential chemical reactions in the body, including those involved in energy metabolism, cell growth and repair, protection from free radical damage, and nerve and muscle function. Inadequate intake of vitamins and minerals leading to a body or tissue deficiency, will impair the athlete’s health and performance.
• Athletes who restrict their total energy intake or lack dietary variety are at risk of an inadequate intake of vitamins and minerals.
• There is no evidence that supplementation with vitamins and minerals enhances performance except in cases where a pre-existing deficiency exists.

Many different products providing combinations of vitamins and minerals are available. Supplements promoted as a daily replacement for adequate dietary intake typically contain a broad range of vitamins and mineral in doses within the range of population NRVs (nutrient reference values).

• Supplementation of inadequate vitamin and mineral intake from food sources may be justified when there is an unavoidable reduction in energy intake or the nutrient density of dietary intake.
  • A prolonged period of travel, particularly to countries with an inadequate or otherwise limited food supply.
  • A prolonged period of energy restriction needed to manage weight or body composition goals.
  • Restricted dietary intake in fussy eaters or athletes with significant food intolerances who are unable/unwilling to increase food range.
  • Heavy competition schedule, involving disruption to normal eating patterns and reliance on a narrow range of foods and sports foods.
• The selection of a suitable product should be based on its composition (preferably containing a broad range of vitamins and minerals in doses that mimic population NRVs and avoiding the presence of unnecessary herbal ingredients) and its origin (preferably manufactured by a pharmaceutical company or large and well-known supplement company where Good Manufacturing Practices are in place).

Poor replacement of nutrient-dense foods

• May provide a false sense of security to athletes who are otherwise eating poorly.
• Vitamin and mineral supplements are often considered a replacement for a poor intake of fruits and vegetables. However, they do not contain the huge variety of phytochemicals found in fruits, vegetables, herbs, and spices that promote health-related effects.

Poor replacement of targeted micronutrient therapy

Multivitamin mineral supplements do not replace the potential need for the supervised treatment or prevention of deficiencies of key micronutrients (e.g. iron deficiency). Athletes who are at high risk of such a deficiency should seek the advice of a Medical Practitioner or Accredited Sports Dietitian rather than self-medicate.

Megadose products may be counterproductive

Large doses of antioxidant vitamin supplements (e.g Vitamins C and E) may be counterproductive if they upset the balance of the body’s complex antioxidant system. In some cases, such supplementation has been shown to impair the effectiveness of training by dampening the oxidative pathways that are needed to signal the adaptive response to an exercise session.¹

Accumulation of excessive and unnecessary doses

Many athletes consider vitamins and minerals to be a “pick me up” in times of heavy training or fatigue. They may add a multivitamin mineral supplement (or two) to their existing use of supplements and sports foods, some of which are already fortified with the same ingredients. The combination of many different sources can lead to unnecessarily high intakes of some micronutrients with unwanted side effects including toxicity or competition for absorption between nutrients.

Inadvertent ingestion of banned or harmful substances

Although all sports foods and supplements can be a source of contaminants or undeclared ingredients, the current positioning of vitamin and mineral supplements as a “pick me up” or lifestyle tonic merits particular caution. We note that some products contain herbal ingredients or other forms of stimulants that are included to give a sense of “energy” - these may lead to health concerns or an inadvertent Anti-Doping Rule Violation.

1. Merry TL, Ristow M. (2016). Do antioxidant supplements interfere with skeletal muscle adaptation to exercise training? J Physiol. 594(18), 5135-47.

• Probiotics are live microbial food supplements that may have beneficial effects on intestinal microbial balance and associated impact on health. The two main species used in commercial preparations are lactobacillus acidophilus and bifidobacterium bifidum.
• Microbes have been used for many years in food preparation – for example, the manufacture of yoghurt and cultured dairy foods, kombucha and alcoholic fermentations. In recent years, a number of different probiotic formulations and supplements have been scrutinised in scientific research (primarily in infants) to examine their impact in modulating gut bacteria or microbiota. The gut microbiota performs several vital functions, including regulating mucosal immune activity, modulating host metabolic activity and protecting against intestinal infection. Dietary manipulation may enhance gut bacteria composition and metabolic activity and promote optimum immune function.
  • Dietary modification, and in particular increasing grain or fibre intake, should be recognised as the primary factor in enhancing gut microbiota diversity, and this can occur within a few days of dietary manipulation. Only after this has been optimised, should consideration be given to probiotic supplementation.
• Beneficial effects of enhancing the gut microbiota diversity may include improved intestinal tract health, enhanced immune system¹, greater bioavailability of nutrients, reduced lactose intolerance, lower prevalence of allergy in susceptible individuals, and improved mental health.² 
• Apart from gut and respiratory health³, the purported benefits of enhancing gut microbiota diversity in a sporting context include improved body composition and lean body mass, reduction in stress hormones such as cortisol, attenuating age-related declines in testosterone levels, and increased concentration of neurotransmitters that might enhance cognition and mood^.4
• The mechanisms of action of probiotic supplementation are largely unknown, but may involve altering the makeup of gut microbiome, modifying gut pH (acidity), producing antimicrobial compounds, modulating gut permeability, stimulating immunomodulatory cells, preventing pathogen infection through ‘competitive exclusion’, or limiting the GI tract surface area available for colonisation.⁵
• Issues with dosage, viability of probiotic strains, lack of industry standardisation and potential safety issues, are being further investigated in the food additives industry and research studies. Applications of probiotics in sports nutrition and medicine are still emerging.⁶
• Although most studies in active individuals and athletes report positive effects on health, there is little evidence showing improvements in sporting performance. The general consensus is that probiotics may confer small variable benefits in performance and recovery, but further laboratory, clinical and field-based studies are required to provide definitive guidelines for athletes.

• Probiotics can be obtained from both foods and commercial supplements. Foods such as yoghurt and cultured milk products, and fermented drinks such as kombucha and kefir are a good choice given synergistic effects between food compounds and probiotic cultures. Supplements may be purchased in shell-stable (dried) format for easy use at home or when travelling, or as products that need to be refrigerated.
• Most studies report effective dosages of 10⁹-10¹⁰ organisms per day (i.e. – 1-50 billion bacteria). This concentration corresponds to about one litre of acidophilus milk (formulated at 2 x 10⁶ colony forming units/millilitre (cfu/ml). Some commercial preparations available in 2020 have up to 25 – 50 billion bacteria per dosage. Studies and clinical experience at the AIS have shown that most athletes will safely tolerate dosages of up to 35 – 50 billion in the commercial preparations that are currently available. Lower levels may benefit some individuals. Daily consumption is recommended as probiotics will pass through the intestine.
• The shelf-life of most probiotic products is about 3 – 6 weeks when kept at 4^oC. The shelf-life of dried supplements is about 12 months, but levels of probiotics may drop significantly over this time.⁷ The concentration of bacteria in food products varies substantially and some research indicates that commercially available products contain no live bacteria.

• Only after manipulation of diet to facilitate an increase in gut microbiota diversity, should probiotic supplementation be considered.
• Athletes with a prior history of gastrointestinal problems during periods of heavy training or around the time of competition might benefit from a course of probiotics.^8,9
• The AIS research on probiotics points to benefits in reducing the effects of respiratory illness.^10-15 Given the reasonable likelihood of athletes experiencing symptoms of gut and/or respiratory illness at some point in a training and competitive season a prophylactic approach before specific periods of training or major competition could be useful.
• Irrespective of whether the application is targeted or prophylactic an individual needs to commence daily supplementation approximately 14 days before domestic or international travel, competition or elevated training load, to allow for colonisation of bacteria in the gut.

May cause GI side-effects

• Some individuals report mild symptoms of stomach rumbles, increased flatulence or changes in the stool during the first week of supplementation as the gut microflora changes to accommodate the newly introduced species. These symptoms may be reduced by a gradual introduction of the probiotic protocol, building up to the recommended dose over a week or two.
• Individuals with a prior history of gastrointestinal tract problems such as coeliac disease or irritable bowel syndrome may be at greater risk of side effects such as an upset stomach or bowel problems.

Some products may not provide sufficient numbers or types of probiotics

• Several studies have reported low viability for commercially-available probiotic formulations and supplements with insufficient numbers of species, and in some cases the presence of species different to those declared on the label.
• Individuals are advised to obtain probiotics through a reputable source such as a sports dietitian or their sporting organisation/program. Priority should be given to evidence-based probiotics that have been tested independently under controlled conditions.

Evidence for benefits is still lacking certainty

Benefits may be highly specific to certain individuals and scenarios of use. Although most studies report positive health effects in athletes and active individuals, there is still no substantial scientific evidence to suggest that probiotics play an important role in improving an athlete's performance. Further research is needed before definitive protocols can be established to identify the likely health and performance benefits, supplementation protocols around training, travel and competition, and interaction with other targeted dietary practices.

1. Clancy RL, Gleeson M, Cox A, Callister R, Dorrington M, D’Este C, et al. (2006). Reversal in fatigued athletes of a defect in interferon gamma secretion after administration of Lactobacillus acidophilus. Br J Sports Med, 40(4), 351-4.
2. Calero CDQ, Rincón EO, Marqueta PM. (2020). Probiotics, prebiotics and synbiotics: useful for athletes and active individuals? A systematic review. Benef Microbes, 11(2), 135-49.
3. Hao Q, Dong BR, Wu T. (2015). Probiotics for preventing acute upper respiratory tract infections. Cochrane Database Syst Rev, 2.
4. Jäger R, Mohr AE, Carpenter KC, Kerksick CM, Purpura M, Moussa A, et al. (2019). International Society of Sports Nutrition Position Stand: Probiotics. J Int Soc Sports Nutr, 16(1), 62.
5. Wosinska L, Cotter PD, O’Sullivan O, Guinane C. (2019). The Potential Impact of Probiotics on the Gut Microbiome of Athletes. Nutrients, 11(10).
6. Leite GSF, Resende Master Student AS, West NP, Lancha AH, Jr. (2019). Probiotics and sports: A new magic bullet? Nutrition, 60, 152-60.
7. Di Pierro F, Polzonetti V, Patrone V, Morelli L. (2019). Microbiological Assessment of the Quality of Some Commercial Products Marketed as Lactobacillus crispatus-Containing Probiotic Dietary Supplements. Microorganisms, 7(11).
8. Sivamaruthi BS, Kesika P, Chaiyasut C. (2019). Effect of Probiotics Supplementations on Health Status of Athletes. Int J Environ Res Public Health, 16(22). ASC36194
9. Walsh NP. (2019). Nutrition and Athlete Immune Health: New Perspectives on an Old Paradigm. Sports Med, 49(Suppl 2), 153-68.
10. Colbey C, Cox AJ, Pyne DB, Zhang P, Cripps AW, West NP. (2018). Upper Respiratory Symptoms, Gut Health and Mucosal Immunity in Athletes. Sports Med, 48(Suppl 1), 65-77.
11. Cox AJ, Pyne DB, Saunders PU, Fricker PA. (2010). Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. Br J Sports Med, 44(4), 222-6.
12. Pyne DB, West NP, Cox AJ, Cripps AW. (2015). Probiotics supplementation for athletes - clinical and physiological effects. Eur J Sport Sci, 15(1), 63-72.
13. West NP, Horn PL, Pyne DB, Gebski VJ, Lahtinen SJ, Fricker PA, et al. (2014). Probiotic supplementation for respiratory and gastrointestinal illness symptoms in healthy physically active individuals. Clin Nutr, 33(4), 581-7.
14. West NP, Pyne DB, Cripps AW, Hopkins WG, Eskesen DC, Jairath A, et al. (2011). Lactobacillus fermentum (PCC®) supplementation and gastrointestinal and respiratory-tract illness symptoms: a randomised control trial in athletes. Nutr J, 10, 30.
15. West NP, Pyne DB, Peake JM, Cripps AW. (2009). Probiotics, immunity and exercise: a review. Exerc Immunol Rev, 15, 107-26.

• Vitamin D is classified as a fat soluble vitamin which acts functionally as a hormone and has a structure that is similar to steroid hormones.
• There are two different isoforms of Vitamin D: D3 (cholecalciferol), which is the important isomer formed in human skin and D2 (ergocalciferol), which is the plant-derived equivalent. D2 was the first isoform to be characterised and was first used in Vitamin D supplements and for food fortification. D3 is now considered preferable. D3 is biologically inert until converted in the liver to 25(OH)D and to 1,25(OH)D in the kidney.¹
• Vitamin D plays an important role in calcium and phosphate homeostasis (bone health), gene expression and cell growth. The recent recognition of Vitamin D receptors in most body tissues indicates a role for Vitamin D in many aspects of health and normal function. Vitamin D is now known to be important for optimal muscle function.
• The principal source of circulating Vitamin D comes from exposure to ultraviolet B (UVB) radiation from sunlight.
• In 2010, the Institute of Medicine issued new Dietary Reference Intakes for Vitamin D, assuming no sunlight exposure; this included a Recommended Dietary Intake of 600 IU/d and an upper-Level intake of 4000 IU/d (www.ncbi.nlm.nih.gov/books/NBK56070/pdf/Bookshelf_ NBK56070.pdf). The Australian Government Department of Health and the New Zealand Ministry of Health developed a Methodological Framework in 2015 to guide future reviews of priority Nutrient Reference Values (NRVs). Assuming no sunlight exposure, the adequate intake for Vitamin D in Australia is estimated to be 5 – 15 mcg/day (200 – 600 IU/day), depending on age and sex (www.nrv.gov.au/nutrients/vitamin-d).
• Vitamin D deficiency can lead to several health issues including increased risk of bone injuries, chronic musculoskeletal pain and viral respiratory tract infections.
• There is also emerging evidence that supplementing Vitamin D in athletes with sub-optimal Vitamin D levels may have beneficial effects on athletic performance, especially in relation to strength, power, reaction time and balance.^2-5
• There is no universally accepted definition of Vitamin D deficiency however, the following definitions based on serum levels of 25(OH) Vitamin D are often cited and have the most clinical utility:
  • Vitamin D deficiency: serum levels < 20 ng/ml (50 nmol/L)
  • Vitamin D insufficiency: serum levels < 30 ng/ml (75 nmol/L)
  • Vitamin D sufficiency: serum levels > 30 ng/ml (75 nmol/L)
  • Ideal Vitamin D range*: 75-120 nmol/L
  • Toxicity: > 375 nmol/L when combined with raised serum calcium

  *Higher status may be preferred for athletes to allow a greater safety margin and to optimize performance; some agencies working with elite athletes often set their own thresholds for desired Vitamin D concentrations.

• Several recent studies have shown low levels of vitamin D among athletes.^6-8

• Vitamin D supplements are available for oral intake and intramuscular therapy. Vitamin D3 is the preferable supplement form and is well tolerated.
• Conversions for Vitamin D3
  • Sources: 40 IU = 1 μg
  • [serum]: 2.5 nmol/L = 1 ng/mL
• The principal source of Vitamin D comes from exposure to ultraviolet B (UVB) radiation from sunlight (see Table).

Regional recommendations for sun exposure times for individuals with moderately fair skin. Times for people with highly pigmented skin would be3–6 times longer.

Adapted from⁹

• Small amounts of vitamin D can be found in foods such as oily fish, egg yolks and fortified foods such as milk, orange juice, cereals and margarine. However, even Vitamin-D rich food sources generally provide ~ 40–150 IU per serve and will not meet Vitamin D requirements.

• Athletes who are tested and found to have low levels of Vitamin D should be informed about the important role that Vitamin D plays in health and sporting performance and that supplementation is safe and beneficial.
• Depending on time of year, athletes identified with inadequate Vitamin D status will require 2000 IU/day for 1-2 months to restore status. Thereafter, Vitamin D status should again be verified via a blood test.
• Athletes at risk of Vitamin D deficiency include those who:
  • Have low exposure to sun in training environment (e.g. training indoors or in early morning and late afternoon).
  • Have dark skin pigmentation
  • Live at latitudes > 35 degrees north or south of the equator [Brisbane = 27 degrees, Perth = 32 degrees, Sydney = 34 degrees, Adelaide and Canberra = 35 degrees, Melbourne = 38 degrees, Hobart = 42 degrees).
  • Wear clothing that covers most or all of their body.
  • Regularly use sunscreen or consciously avoid the sun.
  • Are missing limbs (e.g. many athletes with disability).
  • Have gastrointestinal malabsorption (e.g. Coeliac disease or fat malabsorption syndromes).
  • Have a family history of bone injury/disorders or Vitamin D deficiency.

Toxicity

• Over-exposure to UVB (natural sunlight or tanning beds) in an effort to increase vitamin D levels is not recommended as it can lead to sunburn and skin cancer, including melanoma.
• There is some concern, but also dispute, about the level of Vitamin D supplementation that is considered excessive and associated with symptoms of toxicity. More research is required in this area before definitive conclusions can be drawn.

Sports Dietitians Australia
www.sportsdietitians.com.au/factsheets/supplements/vitamin-d

Gatorade Sports Science Institute
www.gssiweb.org/docs/default-source/sse-docs/close_sse_191_v6_final.pdf?sfvrsn=2

Supplement safety information
www.sportintegrity.gov.au/what-we-do/anti-doping/supplements-sport

1. Bikle DD. (2014). Vitamin D metabolism, mechanism of action, and clinical applications. Chem Biol, 21(3), 319-329.
2. Farrokhyar F, Sivakumar G, Savage K, et al. (2017). Effects of Vitamin D Supplementation on Serum 25-Hydroxyvitamin D Concentrations and Physical Performance in Athletes: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Sports Med, 47(11), 2323-2339.
3. Owens D, Allison R, Close G. (2018). Vitamin D and the Athlete: Current Perspectives and New Challenges. Sports Med, 48(Suppl 1), 3-16.
4. Sivakumar G, Koziarz A, Farrokhyar F. (2019). Vitamin D Supplementation in Military Personnel: A Systematic Review of Randomized Controlled Trials. Sports Health, 11(5), 425-431.
5. Yao P, Bennett D, Mafham M, et al. (2019). Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA
   Netw Open, 2(12).
6. Aydın C, Dinçel Y, Arıkan Y, et al. (2019). The effects of indoor and outdoor sports participation and seasonal changes on vitamin D levels in athletes. SAGE Open Med, 12, 7.
7. Fishman M, Lombardo S, Kharrazi F. (2016). Vitamin D Deficiency Among Professional Basketball Players. Orthopaedic J Sports Med, 4(7).
8. Książek A, Zagrodna A, Słowińska-Lisowska M. (2019). Vitamin D, Skeletal Muscle Function and Athletic Performance in Athletes-A Narrative Review. Nutrients, 11(8), 1800.
9. Nowson C, McGrath J, Ebeling P,wt al. (2012). Working Group of the Australian and New Zealand Bone and Mineral Society, Endocrine Society of Australia and Osteoporosis Australia. Vitamin D and adult bone health in Australia and New Zealand: A position statement. MJA, 196(11), 686-7.

• Zinc is a trace element, widely distributed in the human body that plays a critical role in carbohydrate and fat metabolism, as well as immune function and expression of genetic information. More than 85% of total body zinc is found in skeletal muscle and bone.
• Zinc has an important role in immune system function,² and in line with this, zinc deficiency has been associated with increased infection risk, particularly in developing countries.2-3 Zinc has been found to inhibit replication of rhinovirus (the most frequent cause of the common cold)7 in vitro, however this has not been proven in vivo to date.^3,6
• The body cannot produce its own source of zinc and therefore it relies on absorbing the zinc we consume as part of our diet or supplements. The recommended daily intakes of zinc for adults are:
  • ♂ — 14 mg per day
  • ♀ — 8 mg per day
• Almost 80% of daily zinc intake in western populations comes from meat, fish, poultry, fortified breakfast cereals & milk. In general, zinc intake correlates well with protein intake.
• Zinc supplementation may result in reduced duration of common cold symptoms, by up to 42%.^1,6

• Predominantly available as a tablet or as a lozenge.
• Intranasal zinc and zinc syrup have also been used.⁶
• Multiple different zinc salts are available and marketed, potentially causing confusion. Elemental (or ionic) dose equivalents listed below.
  • Zinc Acetate: 50 mg (15 mg elemental zinc)
  • Zinc Gluconate: 50 mg (7 mg elemental zinc)
  • Zinc Sulfate: 55 mg (12.5 mg elemental zinc)
  • Zinc Oxide: 50 mg (40 mg elemental zinc)
  • Zinc Citrate: 50mg (15mg elemental zinc)
  • Note: dosages discussed in this document refer to the elemental dose of zinc
• Zinc acetate has the most evidence, although other preparations have also shown efficacy.
• There is more available research on zinc lozenges than zinc tablets, although the available evidence for tablets appears similar to lozenges.⁶
• Combination zinc and vitamin C formulations are also available and marketed for treatment or prevention of upper respiratory tract infections.
  • Please refer to the vitamin C fact sheet to review the evidence and guidelines for Vitamin C supplementation.

• For the management of common cold symptoms, the recommended protocol of usage is: 5 day duration, started as soon as possible (preferably within 24 hours) after onset of infective symptoms suggestive of a common cold.
  • A common cold is a clinical syndrome of mild upper respiratory tract infection that can be caused by a number of viruses.⁵
• Evidence for the most appropriate dosage is unclear, but the best support is for zinc acetate at a dose of 75mg/day or greater (of elemental zinc).^1,6 There is no evidence of greater efficacy for doses over 100mg/day of zinc, therefore a dose of 75-100mg/day of elemental zinc is recommended.
• It must also be noted that the use of zinc is only indicated for the treatment of common cold viruses, not other infections such as bacterial respiratory tract infections or more sinister viral infections such as influenza or COVID-19. Careful consideration should be given to ensuring more sinister infections are excluded (either clinically or with specific testing), noting that the symptom severity of COVID-19 symptoms can vary widely and may be misinterpreted as the common cold by some people

1. Use of zinc supplementation without medical guidance could lead to misdiagnosis

• Symptoms of a common cold (that may warrant the use of zinc) are often non-specific and overlap with illnesses that may require antibiotics (certain bacterial illnesses) or other medical investigation/intervention. This includes the need for isolation due to an infective illness (e.g., with influenza or COVID-19).
• The use of zinc supplementation should be under medical guidance and must not replace or interfere with other standard practices of illness assessment and management.

2. Different zinc preparations and dosing may cause confusion

• Multiple different preparations (zinc salts) and dosages used limit the comparability of studies to date.
• Doses are quoted as the elemental zinc dose, however the available dose may differ as some lozenges contain compounds that more tightly bind zinc ions.¹
• The majority of research has been on zinc lozenges, but there is little direct comparison of zinc lozenges compared to tablets.

3. Side effects- largely mild but worth noting

• Bad taste, nausea and constipation have been reported following zinc supplementation.^1,6,8
• Copper deficiency has also been reported with long term high dose zinc supplementation, presumably because of competitive absorption within the gastrointestinal tract.⁴

Supplement safety information

www.sportintegrity.gov.au/what-we-do/anti-doping/supplements-sport

1. Hemilä, H. Zinc lozenges may shorten the duration of colds: a systematic review. Open Respir Med J 2011; 5: 51-8.
2. Prasad, A. S. (2008). Zinc in human health: effect of zinc on immune cells. Molecular medicine, 14(5), 353-357.
3. Walker, C. F., & Black, R. E. (2004). Zinc and the risk for infectious disease. Annu. Rev. Nutr., 24, 255-275.
4. Hoffman HN, Phyliky RL, Fleming CR. Zinc-induced copper deficiency. Gastroenterology 1988; 94: 508-12.
5. Prasad, A. S., Beck, F. W. J., Bao, B., Snell, D., & Fitzgerald, J. T. (2008). Duration and severity of symptoms and levels of plasma interleukin-1 receptor antagonist, soluble tumor necrosis factor receptor, and adhesion molecules in patients with common cold treated with zinc acetate. J Infect Dis, 197(6), 795-802.
6. Johnstone, J., Roth, D. E., Guyatt, G., & Loeb, M. (2012). Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. CMAJ, 184(10), E551-E561.
7. Hemilä, H. (2017). Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage. JRSM open, 8(5), 2054270417694291.
8. Singh, M., & Das, R. R. (2013). Zinc for the common cold. Cochrane Database of Systematic Reviews, (6)

Following ingestion, caffeine is rapidly absorbed and transported to all body tissues and organs where it exerts a large variety of effects. The mechanisms underpinning these effects may vary between individuals and include both positive and negative responses. Evidence of the use of caffeine to enhance sports performance has been developed over more than a century of scientific testing, with robust evidence² now confirming the following:

• Small caffeine doses (e.g. 2-3 mg/kg (~200 mg)) are effective at improving performance, irrespective of whether the caffeine is ingested before and during (in the case of endurance tasks) exercise.
• The major benefits of this dose of caffeine on exercise capacity and performance appear to be achieved by central nervous system effects, specifically those involving antagonism of adenosine receptors. These effects reduce the perception of fatigue and allow optimal pacing and skill/work outcomes to be maintained for a longer period.
• In addition, caffeine increases the mobilisation of fats from adipose tissue and at the muscle cell, can change to muscle contractility. While these effects exist, they are less likely to explain the magnitude of performance changes observed in the current literature.
• Individuals vary in their response to caffeine intake. Although caffeine may enhance sports performance in most, some individuals are nonresponders and others may respond negatively to caffeine ingestions.
• Athletes should be made aware of the potential of these effects and practitioners should be encouraged to trial its use with athletes before use in major competitions.

Caffeine was removed from the World Anti-Doping Agency Prohibited List in 2004, allowing athletes who compete in WADA sanctioned sports to consume caffeine within their usual diets or for specific purposes of performance. This change was based on the recognition that caffeine enhanced performance at doses consistent with everyday use, and that monitoring caffeine intake via urinary caffeine concentration was not reliable. WADA continues to test urinary caffeine concentrations within its Monitoring Program to investigate patterns of misuse. Pure or highly concentrated caffeine can be potentially lethal and hence pose an acute risks to consumers.

Caffeine (1,3,7-trimethylxanthine), is a substance found naturally in the leaves, beans and fruits of a variety of plants, and is regularly consumed by ~90% of adults. The most common dietary source of caffeine is coffee, but tea, cola drinks, energy drinks, chocolate and specialised sports foods and supplements also contribute to regular intake. In its pure form, caffeine is a fine white powder, similar in appearance to icing sugar.

The most recent national data suggests the average intake of caffeine by adult Australians is ~175 mg/day (~2-2.5 mg/kg body mass/day) with at least 25% of the population consuming >230 mg/day (3+ mg/kg body mass/day).

A range of products provide caffeine in our everyday diets. Table 1 provides a summary of common foods, drinks and over-the-counter preparations available in Australia, while Table 2 provides a summary of products that are more specifically targeted to athletes. Important points to note are:

• The manufacture of caffeine containing products in Australia is regulated variously by Food Standards Australia New Zealand (“FSANZ”) or the Therapeutic Goods Administration. Foods, which naturally contain caffeine and have a long history of use and consumer awareness/ association with caffeine, such as tea, coffee and cocoa, are exempt from labelling requirements and the addition of these caffeine sources to other foods is allowed.
• The values for foods with naturally occurring caffeine (e.g. coffee, tea, guarana) are “typical” or “average” amounts. However, there can be a considerable range in the actual caffeine content of these products.
• Coffee can potentially provide a substantial dose of caffeine in a single serve. Studies of beverages purchased from commercial outlets have documented caffeine doses of >200 mg in a small volume caffeine beverage and >500 mg in a large volume beverage from specialty coffee franchises.
• The caffeine content of commercial coffee varies. This variability is evident when the same beverage is purchased from different locations of the same franchise, or the same beverage is purchased from the same location on different days. Therefore, it is difficult to predict or guarantee a dose of caffeine using commercial coffee as a source.
• Iced coffee and cold caffeinated drinks (i.e. frappes) can also contain a substantial dose of caffeine with a commercially available single serve providing up to 200 mg of caffeine.
• Cola drinks, energy drinks, sports foods and therapeutic goods represent an additional source of caffeine in the food supply and are a popular choice among specific population groups (e.g. adolescents and young adults). While cola drinks have been available for over a century, “energy” drinks are a more recent and increasingly popular caffeine source.

The Australian Foods Standards Code allow for the addition of caffeine to cola drinks at a maximum level of 145 mg/L while energy drinks, known in the code as Formulated Caffeinated Beverages, can contain caffeine from all sources (caffeine and guarana) of up to 320 mg/L. Energy drinks must state their caffeine content on product labels. The Australian Food Standards Code provides greater regulation of caffeine-added products than found in other countries. It restricts the development of new food products containing non-traditional sources of caffeine (including guarana) beyond the current provisions. In Aug 2019, FSANZ released a further review of “Pure and highly concentrated caffeine products” and recommended a further review of FSANZ Standard 2.9.4 – Formulated Supplementary Sports Foods. This review is currently underway.

Table 1: Caffeine content of common foods, drinks and therapeutic products (Australia)

Some carbohydrate-containing sports foods, such as sports drinks, gels and bars contain small amounts of caffeine – typically, 20-100 mg per serve (see Table 2). Two other supplement categories also typically contain a source of caffeine: Fat loss products and Pre-workout supplements. Table 2 provides examples of products available in Australia, which fall under the jurisdiction of Therapeutic Goods Administration. Concerns regarding these supplement categories include the lack of information on the caffeine dose provided by a typical serve of these products and the potential for large caffeine doses.

Table 2: Caffeine content of common sports foods and supplements (Australia)

AC = Anhydrous (Pure) Caffeine, * values taken from2, † values taken from product label

Over the last 15 years a large number of studies have refined our understanding of caffeine’s performance enhancing effects. If there is a dose–response relationship between caffeine intake and exercise performance (i.e. the bigger the dose, the better the performance outcome), the plateau seems to occur at a dose of ~3 mg/kg or ~200 mg. This offers athletes (both male and female) the opportunity to consume caffeine for performance benefits at doses that are less likely to cause side effects increases in heart rate, impairments or alterations of fine motor control and technique, and anxiety or over-arousal), well within normal population caffeine use patterns, and from the caffeine doses provided by a range of well accepted foods and sports foods.

It appears that a variety of protocols of caffeine intake that can enhance performance. These include the consumption of caffeine before the exercise bout, spread throughout exercise, or late in exercise as fatigue is beginning to occur. Different protocols may achieve optimal performance outcomes even in the same sport or individual. Suitable or optimal protocols may be dictated by the specific characteristics of the event, the practical considerations of consuming a caffeine-containing product, and the individual characteristics/preferences of the athlete. Athletes intending to use caffeine to enhance sports performance should work with their high performance team providers to develop a protocol(s) and trial these t in training or less important events to determine the protocol(s) which best suit their individual needs.

Performance benefits have been observed following caffeine administered in capsules, coffee, sports and energy drinks, gum, gels, bars and dissolvable mouth strips. Mouth rinsing with caffeine or aerosol caffeine administration appear less likely to produce an ergogenic effect. In addition, studies now show that benefits from caffeine occur soon after intake and are not reliant on the achievement of peak blood caffeine concentrations which typically occur around 60mins.

There is doubt about the value of withdrawing from caffeine use prior to using it for competition to “heighten” the subsequent effect on performance. Observations of a greater performance improvement following a period of caffeine abstinence may be an artefact – caffeine withdrawal may impair general well-being and performance and the apparent increase in benefits when caffeine is reintroduce is partly explained by the reversal of these negative effects. Well-designed studies show that there is no difference in the performance response to caffeine between non-users and users of caffeine, and that withdrawing athletes from caffeine does not increase the net improvement in performance achieved with caffeine supplementation. While most studies of caffeine and performance have been undertaken in laboratories, (fewer investigations on elite athletes using field/real-life sports conditions), there is sound evidence that caffeine is likely to enhance the performance of a range of sports, including:

• Endurance sports (> 60 min)
• Brief sustained high-intensity sports (1-60 min)
• Team and intermittent sports – work rates
• Team and intermittent sports – skills and concentration
• Single efforts involving strength or power

In summary, athletes are able to ingest performance-enhancing doses (~200 mg) of caffeine from common foods/beverages. Athletes who want to use caffeine to enhance sports performance should develop supplementation protocols that use the lowest effective caffeine dose.

Safety

Excessive caffeine intake has been linked with a number of health issues. Pure or highly concentrated caffeine can be potentially lethal and hence poses an acute risks to consumers. Death has been reported after a single dose of 3g of pure caffeine. As such, in 2019, the Therapeutic Goods Administration took steps to prevent the sale of pure-caffeine products within Australia. Other caffeine side-effects include increases in heart rate, impairments or alterations of fine motor control and technique, and anxiety or over-arousal.

In terms of caffeine within food products, various international health agencies consider caffeine to be a generally safe compound for to adults to consume, especially when low to moderate doses are ingested. These doses are commonly defined as

• ≤400 mg/day from all sources (except for pregnant individuals), and
• ≤200mg at any one time

The use of caffeine by children carries greater risk, and children <18 years are suggested to limit caffeine intake to <2.5 mg/kg/d.

We would advise that choosing caffeine from therapeutic sources such as No Doze is preferable over choosing caffeinated pre-workouts as these sports products can contain variable amounts of caffeine and also pose a risk of containing banned substances.

Sleep

Caffeine can affect sleep onset and quality, even at low levels of intake. This may interfere with the athlete’s ability to recover between training sessions, or multi-day competitions. Given the half-life of caffeine is ~5 hours (i.e. about half the drug remains in your blood after this period), consideration should be given to the timing of caffeine intake relative to the need for sleep.

Dehydration

Small to moderate doses of caffeine have minimal effects on urine losses or the overall hydration in people who are habitual caffeine users. In addition, caffeine-containing drinks such as tea, coffee and cola drinks provide a significant source of fluid in the everyday diets of many people.

Genetics

The effects of caffeine vary markedly between individuals. Each athlete should make decisions about caffeine use based on experience of their own responsiveness and reactions, including side-effects. It remains unclear whether genetic differences related to caffeine metabolism or adenosine receptor density explain the contrasting performance effects³.

1. McLellan, T., J. Caldwell, and H. Lieberman. (2016). A review of caffeine’s effects on cognitive function, physical and occupational performance. Neuroscience and Biobehavioral Reviews, 71, 294-312.
2. Desbrow, B., et al. (2018). Caffeine content of pre-workout supplements commonly used by Australian consumers. Drug Test Anal, 11(3), 523-529.
3. Pickering, C. and J. Grgic. (2019). Caffeine and Exercise: What Next? Sports Med, 49(7), 1007-1030.

• The current interest in ß-alanine was initiated by research from Professor Roger Harris (who also lead the original studies into creatine supplementation) and colleagues who found that chronic supplementation with ß-alanine leads to an increase in muscle carnosine content¹ and subsequently improves high-intensity cycling capacity.²
• Carnosine is a L-histidine-containing dipeptide found in several human tissues but displays its highest concentration in skeletal muscle and is formed from the amino acids ß-alanine and L-histidine. Carnosine can be found in red meat, white meat and fish but is rapidly broken down to ß-alanine and L-histidine following ingestion. Thus, carnosine supplementation does not augment muscle carnosine content.
• Carnosine plays several key physiological roles including:
  1. Proton buffering
  2. Regulating calcium
  3. Preventing antiglycation
  4. Acting as an antioxidant
• Carnosine is an extremely stable muscle metabolite but it does have a large between individual variability which may be moderated by:
  1. Muscle fibre type composition (carnosine is ~two-fold higher in type II muscle fibres)
  2. Sex (carnosine is lower in women compared to men)
  3. Specific Muscle Group (carnosine concentration varies across different muscles; for example, carnosine is lower in the soleus compared to gastrocnemius)
  4. Age (carnosine increases following puberty in males and tends to increase in females and then gradually decreases with age)
  5. Athlete type (highest in sprint/explosive athletes compared to endurance athletes)
  6. Diet (ß-alanine increases muscle carnosine and one cross-sectional study³ has shown lower levels of carnosine in vegans but a 6-month vegetarian diet in omnivorous women did not decrease muscle carnosine content⁴)
• Numerous studies have demonstrated substantial increases in muscle carnosine in responses to a variety of ß-alanine supplementation protocols (~3.2- 6.4g·day⁻¹, for periods ranging from 4 to 24 weeks) and supplementation protocols of this duration appear to be safe.^5,6
• Although L-histidine is an essential amino acid in humans, it is found in sufficient supply in the body, whereas ß-alanine is not. As such, ß-alanine is considered to be the rate limiting amino acid to carnosine synthesis (Harris et al., 2006). It should be noted that although L-histidine is not rate limiting, its availability is not unlimited and may decline upon chronic ß-alanine supplementation.⁷
• The increase in muscle carnosine has been shown to improve high-intensity endurance performance in both trained and untrained individuals across a range of exercise capacity tests, fixed duration and intermittent exercise tasks that are typically within a range 30s-10min in duration.⁸ There are specific examples of when exercise performance may be augmented outside of this duration, whereby more prolonged exercise tasks could be enhanced by an improvement in sprint performance following prolonged exercise.⁹ Furthermore, one study has also shown that ß-alanine supplementation can increase training intensity during a 5-week mesocycle of sprint-interval training in well-trained cyclists.¹⁰
• Increasing muscle carnosine content with chronic ß-alanine supplementation may offer an alternative to acute sodium bicarbonate loading for high-intensity exercise given that the latter may be associated with gastrointestinal upset in some athletes. Theoretically, ß-alanine loading may also offer an additive effect to bicarbonate supplementation given that muscle carnosine is an intracellular buffer, while bicarbonate facilitates extracellular buffering. The weight of evidence suggests that co-supplementation may result in a small effect size improvement compared to ß-alanine supplementation alone.⁸
• Despite ß-alanine being a common ingredient in “pre-exercise” supplement formulas (i.e., acute supplementation) used by athletes there is no evidence that acute supplementation is advantageous to performance.¹¹

• ß-alanine supplements include instant release powders and capsules as well as sustained release preparations.
• Although the sustained and rapid release formulations result in similar increases in muscle carnosine when matched for the amount of ß-alanine ingested^12,13, sustained release ß-alanine would be advisable given that a larger single dose can be ingested with improved whole body retention and sensory side-effects that are not discernible from consuming a placebo.^13,14 As such, a greater daily intake of sustained release ß-alanine could be tolerated given that paraesthesia symptoms would be mitigated using this formula.
• Efficacy of ß-alanine supplementation is not dependant on baseline muscle carnosine levels or sex and there does not appear to be any nonresponders, although the increase in muscle carnosine content between individuals can vary.
• Muscle carnosine increases are most pronounced during the initial weeks of ß-alanine supplementation, whereby the increase in muscle carnosine content is greater during the first compared to subsequent 12 days of supplementation⁷, and the first 4 weeks compared to the remaining 20 weeks of supplementation.⁶
• The initial review conducted by Stellingwerff et al.¹⁵ detailing the ß-alanine prescriptive application to augment muscle carnosine highlighted a linear relationship between the total amount of ß-alanine ingested and the subsequent relative increase in muscle carnosine (%) and suggested that for a desired ~50% increase in muscle carnosine, a total of ~230 g of ß-alanine must be taken (within a daily consumption range of 1.6–6.4 g·day^-1). However, a more recent review¹⁶ has indicated that the muscle carnosine increase in response to ß-alanine supplementation is nonlinear, and that the greatest increases occur in the earlier stages of supplementation. One long term supplementation study (24 weeks) did demonstrate substantial further increases in muscle carnosine in the final 4 weeks of supplementation but there was no clear evidence of further improvements in high-intensity cycling capacity.¹⁷
• Once muscle carnosine is augmented, the washout is very slow (~2%·wk-1).¹⁵
• The efficiency of carnosine loading is significantly higher when ß-alanine is co-ingested with a meal (+64%) compared with in between meals (+41%), suggesting that insulin stimulates muscle carnosine loading.¹²
• Carnosine loading is more pronounced in the trained vs. untrained muscles of athletes, whereby the increase in carnosine is greater in arm (deltoid) vs. leg (soleus + gastrocnemius) muscles in kayakers, whereas the reverse pattern is observed in cyclists. Swimmers observe significantly higher increases in carnosine in both deltoid and gastrocnemius muscle compared with nonathletes. These findings suggest that training status and/or exercise training itself is a possible determinant of carnosine loading, but it remains to be determined whether these effects are due to the acute exercise effects and/or to chronic adaptations of training.

• The most practical supplementation regimen entails athlete’s consuming a 1600 mg dose of ß-alanine with their 3 main daily meals and largest snack each day (i.e., 6400 mg of ß-alanine per day spread evenly over four eating times). This is likely to reduce the incidence and severity of paraesthesia, maximise carnosine loading by co-ingesting ß-alanine with meals and promote compliance for athletes.
• While the time-to-maximal carnosine content is variable (mean 18 wk with 6.4 g·d^-1; range 4 to 24 wk), a minimum supplementation period of 4 weeks would be advisable in order to obtain an ergogenic benefit for specific exercise tasks (see below). However, it is not clear whether further increases in muscle carnosine (beyond those achieved with 6.4 g·d^-1 for 4 wk) result in additional improvements in exercise performance.¹⁷
• A maintenance dose of ~1.2 g·d^-1 ß-alanine seems to be sufficient to maintain muscle carnosine content elevated at 30%-50% above baseline for a prolonged period.
• Supplementation with ß-alanine in the weeks preceding a period of training where training intensity is prioritized and/or prior to periods of competition when it is desirable to maximize performance.
• There is good evidence to support the use of ß-alanine by athletes undertaking high-intensity endurance events whereby:
  • Sustained competitive events last 30 seconds to 10 minutes (e.g. rowing, swimming, track cycling, middle distance running):
  • Repeated bouts of high-intensity efforts are performed including:
    • High intensity interval and resistance training.
    • Team and racquet sports.
  • High-intensity effort(s) are undertaken within or at the end of prolonged exercise (e.g. road cycling and distance running).
• The chronic increase in muscle carnosine may increase muscle buffering capacity or improve other mechanisms within the muscle e.g. antioxidant activity) that could enhance training adaptations by increasing training capacity.

• Acute doses of instant release ß-alanine exceeding 800-1600 mg result in paraesthesia which is an uncomfortable tingling sensation on the skin that can last up to an hour. Although the exact cause of paraesthesia is unknown, it is thought to be due to ß-alanine activated strychninesensitive glycine receptor sites in the brain and central nervous system and the mas-related gene family of G protein coupled receptors¹⁸, which are triggered by interactions with ß-alanine.¹⁹ Sustained release formulations directly reduce the symptoms of paraesthesia.
• Human skeletal muscle has an extremely large capacity for carnosine loading and commonly used supplementation protocols (e.g., 4 weeks at 6.4 g·day⁻¹) may not come close to saturating muscle carnosine. Further research is required to better understand the efficacy of longer supplementation protocols in order to maximise muscle carnosine.
• The carnosine loading efficiency following chronic orally ingested ß–alanine is very low (~3%)¹² so further strategies could be developed to increase carnosine loading efficiency.
• Although ß-alanine is considered the rate-limiting precursor for carnosine synthesis, one recent study⁷ demonstrated that L-histidine levels were significantly decreased in blood plasma (-30.6%) and muscle (-31.6%) in subjects who supplemented with ß-alanine alone (6.0 g·d^-1 for 23 d), while the decrease in L-histidine was prevented when ß-alanine and L-histidine (3.5 g·d^-1) were supplemented simultaneously. Furthermore, despite not being statistically significant, Varanoske et al.¹³ observed an ~18.0% decrease in muscle L-histidine following 28 d of ß-alanine supplementation (6.0 g·d^-1). However, more research is required to determine the significance of the decline in L-histidine observed in some studies and whether the co-supplementation of L-histidine and ß-alanine is advantageous compared to ß-alanine supplementation alone.
• Given the chronic nature of the ß-alanine supplementation protocol required for carnosine loading, ß-alanine products may be expensive and require a substantial financial commitment. Therefore, the athlete should be assured that they are using a sound supplementation protocol and applying it to a situation in which there is evidence or a strong hypothesis of performance enhancement.
• Given that ß-alanine supplementation may enhance training capacity during sprint-interval training, athletes should consider the possibility of an increased risk of injury, illness, or overreaching/fatigue.

1. Harris, R. C., Tallon, M. J., Dunnett, M., Boobis, L., Coakley, J., Kim, H. J., Fallowfield, J. L., Hill, C. A., Sale, C., & Wise, J. A. (2006). The absorption of orally supplied ß-alanine and its effect on muscle carnosine synthesis in human vastus lateralis. AA, 30(3), 279-289.
2. Hill, C. A., Harris, R. C., Kim, H. J., Harris, B. D., Sale, C., Boobis, L. H., Kim, C. K., & Wise, J. A. (2007). Influence of ß-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity. AA, 32(2), 225-233.
3. Everaert, I., Mooyaart, A., Baguet, A., Zutinic, A., Baelde, H., Achten, E., Taes, Y., De Heer, E., & Derave, W. (2011). Vegetarianism, female gender and increasing age, but not CNDP1 genotype, are associated with reduced muscle carnosine levels in humans. AA, 40(4), 1221-1229.
4. Blancquaert, L., Baguet, A., Bex, T., Volkaert, A., Everaert, I., Delanghe, J., Petrovic, M., Vervaet, C., De Henauw, S., Constantin-Teodosiu, D., Greenhaff, P., & Derave, W. (2018). Changing to a vegetarian diet reduces the body creatine pool in omnivorous women, but appears not to affect carnitine and carnosine homeostasis: a randomised trial. BJN, 119(7), 759-770.
5. Dolan, E., Swinton, P. A., Painelli, V. d. S., Stephens Hemingway, B., Mazzolani, B., Infante Smaira, F., Saunders, B., Artioli, G. G., & Gualano, B. (2019). A Systematic Risk Assessment and Meta-Analysis on the Use of Oral ß-Alanine Supplementation. AN, 10(3), 452-463.
6. Saunders, B., Franchi, M., de Oliveira, L. F., da Eira Silva, V., da Silva, R. P., de Salles Painelli, V., Costa, L. A. R., Sale, C., Harris, R. C., Roschel, H., Artioli, G. G., & Gualano, B. (2020). 24-Week ß-alanine ingestion does not affect muscle taurine or clinical blood parameters in healthy males. EJN, 59(1), 57-65.
7. Blancquaert, L., Everaert, I., Missinne, M., Baguet, A., Stegen, S., Volkaert, A., Petrovic, M., Vervaet, C., Achten, E., & De Maeyer, M. (2017). Effects of histidine and ß-alanine supplementation on human muscle carnosine storage. MSSE, 49(3), 602-609.
8. Saunders, B., Elliott-Sale, K., Artioli, G. G., Swinton, P. A., Dolan, E., Roschel, H., Sale, C., & Gualano, B. (2017). ß-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. BJSM, 51(8), 658-669.
9. Van Thienen, R., Van Proeyen, K., Vanden Eynde, B., Puype, J., Lefere, T., & Hespel, P. (2009). Beta-alanine improves sprint performance in endurance cycling. MSSE, 41(4), 898-903.
10. Bellinger, P. M., & Minahan, C. L. (2016). Performance effects of acute ß-alanine induced paresthesia in competitive cyclists. EJSS, 16(1), 88-95.
11. 1. Bellinger, P. M., & Minahan, C. L. (2016). Additive benefits of beta-alanine supplementation and sprint-interval training. MSSE, 48(12), 2417-2425.
12. Stegen, S., Blancquaert, L., Everaert, I., Bex, T., Taes, Y., Calders, P., Achten, E., & Derave, W. (2013). Meal and beta-alanine coingestion enhances muscle carnosine loading. MSSE, 45(8), 1478-1485.
13. Varanoske, A. N., Hoffman, J. R., Church, D. D., Coker, N. A., Baker, K. M., Dodd, S. J., Harris, R. C., Oliveira, L. P., Dawson, V. L., Wang, R., Fukuda, D. H., & Stout, J. R. (2019). Comparison of sustained-release and rapid-release ß-alanine formulations on changes in skeletal muscle carnosine and histidine content and isometric performance following a muscle-damaging protocol. AA, 51(1), 49-60.
14. Décombaz, J., Beaumont, M., Vuichoud, J., Bouisset, F., & Stellingwerff, T. (2012). Effect of slow-release ß-alanine tablets on absorption kinetics and paresthesia. AA, 43(1), 67-76. 1
15. Stellingwerff, T., Decombaz, J., Harris, R. C., & Boesch, C. (2012). Optimizing human in vivo dosing and delivery of ß-alanine supplements for muscle carnosine synthesis. Amino Acids, 43(1), 57-65.
16. Rezende, N. S., Swinton, P., de Oliveira, L. F., da Silva, R. P., da Eira Silva, V., Nemezio, K., Yamaguchi, G., Artioli, G. G., Gualano, B., Saunders, B., & Dolan, E. (2020). The Muscle Carnosine Response to Beta-Alanine Supplementation: A Systematic Review With Bayesian Individual and Aggregate Data E-Max Model and Meta-Analysis. FP, 11(913).
17. 1Saunders, B., de Salles Painelli, V., De Oliveira, L. F., da Eira Silva, V., Da Silva, R. P., Riani, L., Franchi, M., de Souza Gonçalves, L., Harris, R. C., & Roschel, H. (2017). Twenty-four weeks of ß-alanine supplementation on carnosine content, related genes, and exercise. MSSE, 49(5), 896-906.
18. Liu, Q., Sikand, P., Ma, C., Tang, Z., Han, L., Li, Z., Sun, S., LaMotte, R. H., & Dong, X. (2012). Mechanisms of itch evoked by ß-alanine. JN, 32(42), 14532-14537.
19. MacPhee, S., Weaver, I. N., & Weaver, D. F. (2013). An evaluation of interindividual responses to the orally administered neurotransmitter ß-alanine. JAA, 2013.

• Dietary nitrate may be used to enhance the availability in the body of a molecule called nitric oxide (NO). NO is important for a variety of functions that are essential to life, and important to exercise performance, including the regulation of blood pressure and blood flow, mitochondrial respiration, muscle contraction and immune function.
• In our bodies, nitrate is produced continuously because it is formed when the amino acid, arginine, is oxidized to generate NO. Until recently, it was believed that this nitrate had no biological function, but it has now been discovered that it can be recycled to form NO. Specifically, nitrate can be converted into nitrite (this process relies principally on the action of bacteria in the mouth) and then to NO. This nitrate-nitrite-NO pathway might be particularly important when oxygen is in short supply such as in muscle during exercise.
• In addition to the nitrate that is produced within our bodies, the amount of nitrate and nitrite carried in our blood, and stored in our muscles and other organs, can be greatly augmented by the consumption of nitrate in our diet. The main dietary sources of nitrate are vegetables (particularly leafy greens) and some fruits, along with processed meats (where it is added as a preservative) and drinking water.
• Increasing dietary nitrate intake, or using a nitrate supplement, may increase NO bioavailability and have the potential to enhance exercise performance in situations where NO production might otherwise be compromised.¹
• The average dietary intake of adults in the US, Europe and Australia is 1-2 mmol/d (~60-120 mg/d) with vegetables providing about 80% of the total. Vegetarians are likely to consume higher nitrate intakes and people who follow “heart-friendly” eating plans such as the Dietary  Approaches to Stop Hypertension (‘DASH’) diet are also likely to achieve higher nitrate intakes.
• Interest in beetroot juice for enhancing sports performance arises principally from research by Professor Andy Jones and colleagues (University of Exeter, UK) which has used this juice as a rich source of dietary nitrate.
• Nitrate consumed in the diet is rapidly absorbed via the stomach and small intestine, with plasma nitrate levels peaking ~ 1 hour after nitrate ingestion. A significant proportion of the plasma nitrate enters the entero-salivary system and is extracted by the salivary glands and concentrated in the saliva. Bacteria in the mouth convert nitrate to nitrite as part of their metabolism and this nitrite is subsequently swallowed. Some of the nitrite is converted to NO and other reactive nitrogen species in the acidic stomach environment but the remainder enters the small intestine and is absorbed into the blood where it can be transported around the body and reduced to NO if required.
• Plasma nitrite concentrations peak at ~ 2.5 h following the intake of dietary nitrate. Factors that interfere with salivary nitrate handling - such as the use of antibacterial mouthwashes to reduce mouth levels of bacteria - may markedly limit this rise in plasma nitrite and blunt any  subsequent physiological effects.
• Nitrate supplementation has been shown to enhance some of the effects of NO, even in healthy people. For example, supplementation with dietary nitrate sources or nitrate salts (such as sodium or potassium nitrate) has been shown to reduce blood pressure even in individuals with  normal blood pressure.
• Original and subsequent studies have reported that both chronic (3-15 d) and acute (single dose prior to exercise) beetroot juice supplementation can enhance exercise economy (i.e. reduce the oxygen cost of exercise), exercise capacity and sports performance.¹
• Aerobic fitness levels influence the efficacy of dietary nitrate, with highly-trained endurance athletes (with VO2max greater than 65 ml/kg/min) not benefitting significantly from nitrate supplementation.² Few studies have investigated the impact of nitrate supplementation on female athletes.
• Recent studies indicate that dietary nitrate supplementation can enhance muscle power, sprint, multiple-sprint, and high-intensity intermittent exercise performance, thereby widening the potential application of nitrate supplementation to a greater number of both individual and team sports.³

• Nitrate is abundant in green leafy vegetables; increasing the dietary intake of these vegetables is one way to augment nitrate intake. Table 1 summarizes the nitrate content of a range of vegetables, with the best sources being green leafy plants and vegetables grown in low light conditions such as plant roots. The nitrate content of a specific vegetable source can vary considerably from plant to plant and will depend on factors such as climate, soil conditions and time since harvest.
• Typical nitrate dose used in recent studies of sports/exercise performance: ~ 6-8 mmol or ~350-500 mg nitrate provided by a single serve of beetroot juice concentrate, consumed ~ 2-3 hours pre-exercise. As an example, a 70ml shot of Beet It Sport Nitrate (James White, UK, Oz Beet It, Australia) contains 400mg nitrate.
• Preparation of own beetroot sources (i.e. cooked vegetable, relish, juice) may not result in a reliable or sufficiently high nitrate dose for targeted acute supplementation pre-exercise. However, encouraging a higher daily vegetable intake is likely to have numerous benefits, including an increased daily nitrate intake
• Nitrate may also be purchased as sodium or potassium nitrate which is used as a fertilizer and preservative of meats, but this is not recommended, and it is essential not to confuse nitrate with nitrite.
• Based on research demonstrating that nitrate can enhance exercise performance, a large number of beetroot-based supplements are now marketed to athletes, including juice concentrates, gels and powders. Few of these have been independently tested to determine their nitrate content. Preliminary research supports preferential use of beetroot juice concentrates.^{4, 5}
• It is important that the product is guaranteed to contain at least 5-6 mmol nitrate for it to be effective. Preliminary research indicates however, taking more than 10-12 mmol is no more effective than taking 6-8 mmol.⁶

Table 1: Typical nitrate content of vegetables (taken from Bryan NS and Hord NG (2010). Dietary Nitrates and nitrites: in: Bryan N (ed), Food Nutrition and the Nitric Oxide pathway. Destech Pub Inc: Lancaster, PA, pp 59-77)

Recent studies have identified several situations in which exercise capacity or performance has been enhanced by the pre-exercise consumption of beetroot juice/nitrate: these include cycling and running events of 4-30 minutes duration² as well as intermittent exercise protocols designed to reflect the demands of team sports.³

• Supplementation may also be useful in supporting training, and perhaps also during exposure to hypoxic conditions e.g. altitude training.
• It is recommended that a 6-8 mmol (~350-500mg) nitrate dose is consumed 2-3 hours prior to the commencement of exercise or competition. Consuming 6-8 mmol of nitrate daily for several days prior to competition is another possible strategy⁷. As an example, an ingestion protocol used successfully amongst sprint kayakers includes the following, with athletes informed to avoid the use of mouthwashes as this can moderate conversion of nitrate to NO.
  • 1 x Beet It Sport shot am & pm for 3 days pre-race.
  • 2 x Beet It Sport shot 2.5 hrs pre-race.

• During the 1960s, health authorities became concerned about the nitrate and nitrite content of foods, blaming nitrite for health issues including “blue baby syndrome” in infants and an increased risk of colon cancer based on studies in rats. As a consequence, some countries have limits on the permitted levels of nitrate in foods and drinking water.
• In contrast to these previous concerns about the safety of intake of nitrate and nitrite, which are in any case disputed, there is now evidence of benefits to cardiovascular and metabolic health. Indeed, it has been suggested that some of the health benefits of a diet high in vegetables are due, at least in part, to its nitrate content.
• Consuming nitrate in its natural form (i.e., in vegetables and fruits), where it is found alongside antioxidants and polyphenols, rather than via processed meats, is likely to prevent or suppress the formation of any potentially-harmful compounds.
• While it is unlikely that consumption of beetroot juice or other vegetable sources of nitrate is harmful (and may, in fact, may offer other health benefits), chronic use of nitrate supplements has not been well studied.
• Beetroot juice, particularly in concentrated form and larger doses, sometimes causes mild gastrointestinal discomfort. Athletes who are inclined to use nitrate supplementation pre-competition are advised to first practice in training.
• The consumption of beetroot/juice may cause a temporary pink coloration of urine and stools. This is a harmless side-effect.
• Use of sodium nitrate supplements may be associated with a greater risk of misjudging dosages. Some athletes may also mistakenly (or deliberately) use sodium or potassium nitrite as a supplement and therefore expose themselves to toxic effects such as methemoglobinaemia.

1. Jones, A. M., Thompson, C., Wylie, L. J., & Vanhatalo, A. (2018) Dietary Nitrate and Physical Performance. ARN, 38, 303-328.
2. Senefeld, J. W., Wiggins, C. C., Regimbal, R. J., Dominelli, P. B., Baker, S. E., & Joyner, M. J. (2020). Ergogenic Effect of Nitrate Supplementation: A Systematic Review and Meta-analysis. Med Sci Sport Exerc, 52, 2250-2261.
3. Thompson, C., Vanhatalo, A., Jell, H., Fulford, J., Carter, J., Nyman, L., Bailey, S. J., & Jones, A. M. (2016). Dietary nitrate supplementation improves sprint and high-intensity intermittent running performance. NO, 61, 55-61.
4. Gallardo, E. J., & Coggan, A. R. (2019). What is in your beet juice? Nitrate and nitrite content of beet juice products marketed to athletes. Int J Sport Nutr Exerc Metab, 29: 345-349.
5. McDonagh, S. T. J., Wylie, L. J., Webster, J. M. A., Vanhatalo, A., & Jones, A. M. (2018). Influence of dietary nitrate food forms on nitrate metabolism and blood pressure in healthy normotensive adults. Nitric Oxide, 72: 66-74.
6. Wylie, L. J., Kelly, J., Bailey, S. J., Blackwell, J. R., Skiba, P. F., Winyard, P. G., Jeukendrup, A. E., Vanhatalo, A., & Jones, A. M. (2013). Beetroot juice and exercise: pharmacodynamic and dose-response relationships. J Appl Physiol, 115, 325-336.
7. Jones, A. M., Vanhatalo, A., Seals, D. R., Rossman, M. J., Piknova, B., & Jonvik, K. L. (2020). Dietary Nitrate and Nitric Oxide Metabolism: Mouth, Circulation, Skeletal Muscle, and Exercise Performance. Med Sci Sport Exerc, doi: 10.1249/MSS.0000000000002470.

• Bicarbonate is an endogenously produced extracellular anion, and an integral component of the body’s primary pH buffering system. During high rates of anaerobic glycolysis (inevitable during prolonged periods of intense exercise), the muscle can produce hydrogen ions (H+) in excess, which eventuates in metabolic disturbances and ultimately may contribute to fatigue. Extracellular bicarbonate facilitates the removal of these H+, and to a point, supports the body’s ability to match the high rates of energy demand required to maintain muscle contractile function during such activity.
• Numerous studies have demonstrated that endogenous bicarbonate levels can be safely and acutely increased after the oral ingestion of between 200 and 300 mg/kg body mass (BM) of sodium bicarbonate.^1,2 The additional bicarbonate is believed to attenuate the inevitable increase in intramuscular H+, synonymous with high-intensity exercise, although the physiologic mechanisms directly responsible for performance augmentation in humans are unclear.³
  • Meta-analyses have reported that supplementation at these levels can result in an approximate 2 to 3% improvement across a variety of performance measurements (e.g. power, speed, work capacity, time to failure) during both single and repeated bouts of high-intensity exercise typically lasting 1-10 minutes in duration.^4,5,6
  • The 2018 International Olympic Committee Sports Nutrition Consensus Statement recommendations suggest that sodium bicarbonate is one of five dietary supplements that consistently improves performance in the elite athlete.⁷

• The most commonly available and economical source of sodium bicarbonate is the household/baking product baking soda. However, most athletes find ingesting sodium bicarbonate mixed in water or even diluted with cordial to be unpalatably salty.
  • Alternative powder forms of sodium bicarbonate are also found in urinary alkalinisers such as Ural Effervescent Powder (1.75 g per sachet), which also contain other ingredients (e.g. carbohydrates, citric acid and most notably sodium citrate (630 mg)).
• A more palatable delivery of sodium bicarbonate can be provided in tablet or capsule form (e.g. SodibicTM at 840 mg per tablet). While less convenient, filling enteric capsules (e.g. Capsugel®) with either bicarbonate powder or aqueous solution may also be a viable option. This capsule casing is proposed to resist the acidity of the stomach, instead dissolving in the intestine, which may also reduce gastro-intestinal (GI) symptoms of bicarbonate ingestion.⁸
• Transdermal delivery of sodium bicarbonate is commercially available (Amp Human®), however more research is needed on the efficacy of this delivery system.⁹

• Current ingestion recommendations are to consume between 200 to 400 mg/kg BM with a small, carbohydrate dense meal (~1.5 g/kg BM CHO) approximately 120 to 150 min prior to exercise.⁷
  • Broad ingestion recommendations should only serve as a starting point, as several practical issues associated with sodium bicarbonate may influence the efficacy of this supplement such as ingestion timing, individual tolerability and/or susceptibility to GI distress, and the potential co-ingestion of other supplements.^10,11,12 Where practicable, monitoring of blood bicarbonate concentrations and pH in response to sodium bicarbonate ingestion, warm-up and event are also strongly encouraged. Experience at the AIS has shown that this frequently uncovers issues that can be manipulated to enhance outcomes for the individual athlete.
  • There is some preliminary evidence that timing an individual’s ingestion protocol in order to commence competition at their individualized peak blood buffering capacity may improve performance. However, this requires periodically measuring blood bicarbonate changes over multiple testing sequences.¹⁰
  • If individualizing the ingestion strategy is not feasible, ingestion at the higher end of the recommended doses (e.g. 300 to 400 mg/kg BM) 2 to 3 hours pre-competition should significantly elevate blood buffering capacity to levels presumed to be ergogenic (~ 5 – 6 mmol/L increase) with effects lasting for 3 to 4 hours. Co-ingestion with a small high carbohydrate meal supports blood alkalosis while reducing the occurrence of GI symptoms. This method of delivery would allow more time for those athletes susceptible to GI distress (which typically peaks 90 min post-ingestion) to resolve any potential issues before competition.
• There is good evidence for the use of bicarbonate by athletes competing in high-intensity activity lasting from 1 to 7 minutes – for example, swimming, rowing and middle-distance running events.⁴
  • It should be recognized that in many events of this type, competition may require the athlete to undertake several events within a relatively short timeframe, or to compete later the same day. This competition schedule may require an adjustment of sodium bicarbonate loading protocols to account for repeated events. In this example, “split” strategies of loading may be incorporated around time constraints, or alternatively using a “top-up” approach with smaller amounts (e.g. 100 mg/kg BM) consumed once or twice over the remainder of the competition timeframe.⁷ As there is no published data on the efficacy of split- or top-up approaches, this would need to be trialed in training.
  • Alternatively, a bicarbonate supplementation protocol involving multiple divided doses over several days before competition may be appropriate. This involves a higher daily bicarbonate dose (500mg/kg BM) in several even doses (e.g., 100mg/ kg BM with 3 main meals and ² snacks) up to 5 days before competition, as well as the day of competition.¹³
• Over the past decade, there have been a few studies reporting benefits in physical performance improvements in skill-based sports requiring prolonged, repeated high-intensity efforts (e.g. team, racquet and combat sports).
  • Given this evidence, high-intensity events of up to an hour which are conducted at work rates just below an individual’s anaerobic/lactate threshold may also be relevant for sodium bicarbonate supplementation. In this instance, the additional buffering capacity may support the athlete’s ability to increase their pace/work output for strategic periods (e.g. surges, sprint finishes).
• There is a growing body of evidence that suggests increases in aerobic adaptability (e.g. increased oxidative and mitochondrial function) are augmented with sodium bicarbonate supplementation during blocks of interval training sessions.^14,15
  • There is also evidence supporting fatigue attenuation after acute sodium bicarbonate supplementation in measures of explosive power (e.g. rate of force development).^16,17
• There have been studies investigating the efficacy of co-ingestion with other supplements (e.g. caffeine, creatine, beta-alanine, ketone bodies), however presently the evidence is equivocal (with the exception of sodium bicarbonate appearing to counteract the acidity induced by ketosis).

• The major side effect associated with sodium bicarbonate supplementation is gastrointestinal distress, with symptoms including nausea, stomach pain, diarrhoea and vomiting. This is a serious practical consideration for athletes in a competition setting, and this may counteract the potential performance benefits from enhanced buffering.
  • Research undertaken at the AIS systematically studied a series of sodium bicarbonate supplementation protocols, varying the time taken to consume the load (spreading it over 30 to 60 mins), the form of the delivery (flavoured powder or capsules) and the consumption of various amounts of fluid or food with the sodium bicarbonate.4 Of the protocols tested, the best strategy to optimise blood bicarbonate levels and to reduce the occurrence of GI symptoms was to consume capsules in a spread-out protocol, commencing 120 to 150 min before the start of exercise and, if practical, at the same time as consuming a meal composed of carbohydrate-rich food choices and some fluid.
• It is generally advised to ingest sodium bicarbonate capsules or dissolvable powder with sufficient fluid to decrease the risk of hyperosmotic diarrhea (~ 10ml/kg BM).
  • Given the significant amount of fluid intake recommended to alleviate GI distress, consideration may be given toward the additional weight gain this might induce for weight-dependent sports.
• Repeated use of acute loading protocols (e.g. heats and finals in a single or multi-day competition) may require individualized attention to exacerbate the risk of side-effects. This may be reduced if the athlete uses lower doses on subsequent occasions to compensate for bicarbonate remaining in the body.
• Anecdotal feedback from athletes also suggests that those unfamiliar with sodium bicarbonate supplementation may need to experience the supplement on a number of occasions prior to competition, due to the potential for impaired perceptive feedback from the working muscles.
• Changes in urinary pH are expected following bicarbonate supplementation. If an athlete is selected for a drug test, they may need to wait several hours before urinary pH returns to the levels that are acceptable to drug testing authorities. This may cause some disruption to the athlete’s routine.

1. Price M, Singh M. (2008). Time course of blood bicarbonate and pH three hours after sodium bicarbonate ingestion. Int J Sports Physiol Perform, 3, 240-242.
2. Siegler JC, Midgley AW, Polman RCJ, Lever R. (2010). Effects of various sodium bicarbonate loading protocols on the time-dependent extracellular buffering profile. J Strength Cond Res, 24(9), 2551-2557.
3. Siegler JC, Marshall PWM, Bishop D, Shaw G, Green G. (2016). Mechanistic insights into the efficacy of sodium bicarbonate supplementation to improve athletic performance. Sports Medicine – Open, 2, 41.
4. Carr AJ, Hopkins WG, Gore CJ. (2011). Effects of acute alkalosis and acidosis on performance: a meta-analysis. Sports Med, 41(10), 801-814.
5. Peart DJ, Siegler JC, Vince RV. (2012). Practical recommendations for coaches and athletes: a meta-analysis of sodium bicarbonate use for athletic performance. J Strength Cond Res, 26(7), 1975-1983.
6. Hadzic M, Eckstein ML, Schugardt M. (2019). The impact of sodium bicarbonate on performance in response to exercise duration: a systematic review. J Sports Sci Med, 18(2), 271-281.
7. Maughan RJ, Burke LM, Dvorak J, Larson-Meyer DE, Peeling P et al. (2018). IOC consensus statement: dietary supplements and the highperformance athlete. Br J Sports Med, 52(7), 439-455.
8. Hilton NP, Leach NK, Sparks SS, Gough LA, Craig MM, Deb SK, McNaughton LR. A novel ingestion strategy for sodium bicarbonate supplementation in a delayed-release form: a randomized crossover study in trained males. Sports Med – Open, 5, 4.
9. McKay A, Peeling P, Binnie M, Goods P, Sim M, Cross R, Siegler J. (2021). Topical sodium bicarbonate: No improvement in blood buffering capacity or exercise performance. Int J Sports Physiol Perform. (ahead of print)
10. Heibel AB, Perim PHL, Oliveira LF, McNaughton LR, Saunders B. (2018). Time to optimize supplementation: modifying factors influencing the individual responses to extracellular buffering agents. Front Nutr, 5, 35.
11. Boegman S, Stellingwerff T, Shaw G, Clarke N, Graham K, Cross R, Siegler JC. (2020). The impact of individualizing sodium bicarbonate supplementation strategies on world-class rowing performance. Front Nutur, 7, 138.
12. de Oliveira LF, Saunders B, Yamaguchi G, Swinton P, Artioli GG. (2020). Is individualization of sodium bicarbonate ingestion based on time to peak necessary? Med Sci Sports Exerc, ahead of print.
13. McNaughton L, Backx K, Palmer G, Strange N. (1999). Effects of chronic bicarbonate ingestion on the performance of high-intensity work. Eur J Appl Physiol, 80, 333-336.
14. Edge J, Bishop D, Goodman C. (2006). Effects of chronic NaHCO3 ingestion during interval training on changes to muscle buffer capacity, metabolism, and short-term endurance performance. J Appl Physiol, 101, 918-925.
15. Percival ME, Martin BJ, Gillen JB, Skelly LE, MacInnis MJ, Green AE, Tarnopolsky MA, Gibala MJ. (2015). Sodium bicarbonate ingestion augments the increase in PGC-1 m RNA expression during recovery from intense interval exercise in human skeletal muscle. J Appl Physiol, 119, 1303-1312.
16. Siegler JC, Marshall PW, Raftry S, Brooks C, Dowswell B, Romero R, Green S. (2013). The differential effect of metabolic alkalosis on maximum force and rate of force development during repeated, high-intensity cycling. J Appl Physiol, 115, 1634-1640.
17. Siegler JC, Marshall PW, Finn H, Cross R, Mudie K. (2018). Acute attenuation of fatigue after sodium bicarbonate supplementation does not manifest into greater training adaptations after 10-weeks of resistance training exercise. PLOS One, 13, 5.

• Creatine is a non-essential nutrient that is endogenously synthesized (about 1 g/d) and also ingested through the diet (about 1 g/d). Creatine is heavily concentrated in animal muscle (e.g. meat and fish), which is the primary dietary source for omnivores. Muscle and blood creatine levels are reduced in vegetarians who consume little in the diet.¹
• Most creatine is stored in skeletal muscle where it exists in free (i.e. creatine) and phosphorylated (i.e. phosphorylcreatine) forms. Creatine and phosphorylcreatine provide energy to support brief, intense exercise. Although the rate of energy production from muscle creatine is very high, storage capacity is very limited. There is enough creatine in skeletal muscle to support about 8 to 10 seconds of maximal exercise. Creatine monohydrate is a dietary supplement that, when ingested in accordance with current guidelines, can increase skeletal muscle creatine and phosphorylcreatine and subsequently improve high-intensity exercise performance.¹
• A small amount of creatine is present in the brain, where it is also used to support energy production. Brain creatine can be increased with creatine monohydrate supplementation, albeit to a smaller amount than the increase seen in skeletal muscle.² The benefits of creatine supplementation on brain health include improved cognitive processing and potentially reduced damage and enhanced recovery from mild traumatic brain injury (mTBI/concussion).³

• Creatine monohydrate is a white powder that can be ingested after combining it with liquid (e.g. a post-exercise protein-carbohydrate recovery drink) or food (e.g. Greek yogurt). Creatine supplements should be ingested immediately following mixing, as in liquid form, creatine quickly degrades to creatinine.
• Creatine monohydrate is very well absorbed (>99%)⁴ whereas alternate creatine supplements (e.g. creatine ethyl ester) that advertise “better absorption” do not have data to back such claims. Multiple creatine dietary supplements are available for purchase, but about 99% of the safety and efficacy data are available on creatine monohydrate powder. There is no scientific reason to take a creatine supplement other than creatine monohydrate.

• Professor Roger Harris first demonstrated that oral ingestion of creatine monohydrate can increase muscle creatine and phosphorylcreatine. After many years of study, multiple research teams confirm that muscle creatine can be increased by ingesting about 5 grams of creatine monohydrate, 4 times per day, for about 5 days (i.e. “creatine loading”).⁵ Suggested dosing based on body mass is about 0.3 g of creatine/kg body mass per day, for 5 days, typically in 3-4 divided doses (i.e. with meals), followed by a maintenance dose of 0.03g/ kg body mass once a day thereafter.
• Subsequently, Professor Eric Hultman showed that increased muscle creatine could be maintained after creatine loading with ingestion of a maintenance dosage of about 3 to 5 g/d).⁶ Alternatively, one could bypass the loading phase, simply ingest a maintenance dose (3 to 5 g/d), and increase muscle creatine to saturation levels over about 4 weeks.⁶
• Muscle creatine uptake is insulin mediated, so a larger increase in muscle creatine in response to supplementation could be obtained with coingestion of a meal that generates an acute increase in blood insulin levels. Early studies used large amounts of simple sugars to accomplish this (i.e. >90 g of sugar + 5 g creatine four times/d), but subsequent studies confirm the same effect can be accomplished by ingesting creatine following a meal that includes both protein (50 g) and carbohydrate (50 g) rich foods.
• Muscle creatine uptake is similarly increased when supplementation is combined with exercise which has insulin like effects. Although there are not many data to demonstrate that post-exercise creatine ingestion is more effective than pre-exercise ingestion, ingestion of creatine supplements following exercise and with the post-exercise meal is prudent advice and may help athletes establish a habit of proper postexercise nutritional intake.
• Creatine loading is analogous to carbohydrate loading. Physical activities, such as endurance exercise, that are limited by carbohydrate availability and metabolism may benefit from carbohydrate loading (i.e. several days of a high-carbohydrate diet). Physical activities, such as sprinting, that are limited by creatine availability and metabolism may benefit from creatine loading/supplementation.
• Individuals with the lowest muscle creatine (e.g. vegetarians) have the largest potential for increase in response to supplementation. Muscle creatine levels appear to be relatively unaffected by training style or intensity (i.e. sprinters do not necessarily have high muscle creatine and sprint training does not increase muscle creatine). In response to increased (e.g. supplementation) or decreased (e.g. changing to a meat free diet) dietary creatine intake, muscle creatine quickly increases or decreases, respectively.
• It is consistently found that creatine supplementation combined with resistance exercise improves resistance training outcomes, such as muscle strength, endurance, and muscle hypertrophy. This points to creatine supplementation being an effective training aid to augment strength and conditioning programs. See Table 1.
• Creatine supplementation improves the performance of brief (usually <30 sec), high-intensity exercise, especially when there are repeated bouts. These are common characteristics to many team sports, indicating that creatine supplementation can improve sports performance across a wide range of sports and activities. Maximal exercise performance is also enhanced when sprints are included during and/or at the end of endurance exercise events. See Table 1.
• There is some indication that creatine supplementation can improve recovery from periods of disuse atrophy, such as when recovering from an injury. Extremely low levels of physical activity, such as during immobilization, result in decreased muscle creatine, strength, endurance, and mass, among many other adverse changes, while creatine supplementation attenuates or reverses these decrements. See Table 1.
• Creatine supplementation has multiple direct effects on muscle (e.g. increased glycogen, phosphorylcreatine resynthesis, growth factor expression, satellite cell number, cellular hydration, etc.) which could indirectly benefit athletic performance, adaptation to exercise training, or muscular performance in a number of different patient populations.⁷ See Table 1.

Table 1: Known effects of creatine monohydrate supplementation

Table adapted from previous research.¹²

There is no evidence of systematic serious adverse effects related to creatine monohydrate supplementation. Speculation and anecdotes about muscle, renal, and thermoregulatory dysfunction are not supported with research or post-marketing surveillance.^{1, 13} However, there are some implications of creatine supplementation that warrant discussion, including acute weight gain and gastrointestinal tract distress.

Rapid weight gain

• As carbohydrate ingestion and increased muscle glycogen is associated with an acute increase in body mass secondary to increased body water, increased creatine ingestion and muscle creatine is also associated with weight gain/increased body water. However, with creatine supplements, this increase in body mass is maintained as long as muscle creatine remains elevated. Following cessation of creatine supplementation, muscle creatine levels, and subsequently body mass, decrease slowly to normal over 4 to 6 weeks’ time. Although this may only be a maximum of 1 or 2 kg, this could be problematic for athletes attempting to “make weight”.
• Creatine supplementation offers a metabolic advantage but could present a biomechanical disadvantage for some athletes. In theory, body weight supported sports (e.g. running) could be negatively impacted by creatine supplementation. It appears these concerns are unfounded, as studies have showed improved running and swimming performance, but weight gain in some sports such as pole vaulting, in theory, could present a challenge.

Gastrointestinal tract distress

• Some people may experience mild, temporary gastrointestinal (GI) upset during supplementation, although this is anecdotal, and not widely reported in the literature.
• Avoiding the loading phase in favour of the lower-dose, longer-duration supplementation protocol, ingesting creatine with meals, not ingesting creatine at the same time as high-fibre foods or supplements that are known to increase GI disturbances (e.g. sodium bicarbonate) are all sensible decisions to help avoid GI upset.
• As with any dietary supplement, experimentation should be conducted in the off-season.

1. Kreider, R. B., Kalman, D. S., Antonio, J., Ziegenfuss, T. N., Wildman, R., Collins, R., Candow, D. G., Kleiner, S. M., Almada, A. L. & Lopez, H. L. (2017). International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr 14: 18.
2. Dolan, E., Gualano, B. & Rawson, E. S. (2019). Beyond muscle: the effects of creatine supplementation on brain creatine, cognitive processing, and traumatic brain injury. Eur J Sport Sci 19(1): 1-14.
3. Roschel, H., Gualano, B., Ostojic, S. M. & Rawson, E. S. (2021). Creatine supplementation and brain health. Nutrients 13(2): 586.
4. Jäger, R., Purpura, M., Shao, A., Inoue, T. & Kreider, R. B. (2011). Analysis of the efficacy, safety, and regulatory status of novel forms of creatine. Amino Acids 40(5): 1369-1383.
5. Harris, R. C., Söderlund, K. & Hultman, E. (1992). Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clin Sci (Lond) 83(3): 367-374.
6. Hultman, E., Söderlund, K., Timmons, J. A., Cederblad, G. & Greenhaff, P. L. (1996). Muscle creatine loading in men. J Appl Physiol (1985) 81(1): 232-237.
7. Kreider, R. B. & Stout, J. R. (2021). Creatine in Health and Disease. Nutrients 13(2).
8. Hopwood, M. J., Graham, K. & Rooney, K. B. (2006). Creatine supplementation and swim performance: a brief review. J Sports Sci Med 5(1): 10-24.
9. Rawson, E. S. & Volek, J. S. (2003). Effects of creatine supplementation and resistance training on muscle strength and weightlifting performance. J Strength Cond Res 17(4): 822-831.
10. Lanhers, C., Pereira, B., Naughton, G., Trousselard, M., Lesage, F. X. & Dutheil, F. (2016). Creatine Supplementation and Upper Limb Strength Performance: A Systematic Review and Meta-Analysis. Sports Med.
11. Rawson, E. S., Miles, M. P. & Larson-Meyer, D. E. (2018). Dietary supplements for health, adaptation, and recovery in athletes. Int J Sport Nutr Exerc Metab: 1-12.
12. Rawson, E. S. (2018). The safety and efficacy of creatine monohydrate supplementation: What we have leanred from the past 25 years of research. Gatorade Sports Science Exchange 29(186): 1-6.
13. Rawson, E. S., Clarkson, P. M. & Tarnopolsky, M. A. (2017). Perspectives on Exertional Rhabdomyolysis. Sports Med 47(Suppl 1): 33-49.

The oral ingestion of glycerol can be used to facilitate better retention of ingested fluids, which may be of benefit to athletes in sports where hydration status may be compromised due to prolonged and/ or intense exercise in thermally challenging environments and/ or when fluid access may be restricted.¹ Consumed simultaneously with a substantial volume of fluid, glycerol contributes to the osmotic pressure of body fluids and causes a temporary retention of fluid and expansion of body fluid compartments beyond normal fluctuations.^2,3

• Glycerol is a 3-carbon sugar alcohol that forms the backbone of triglycerides. It is stored in most human tissues and is released following lipolysis.
• Glycerol is present in foods as a component of dietary fats derived from plants (e.g., soybeans) or animals (e.g., tallow). It is safe for human consumption.
• Glycerol (Labelled as E422) is added to manufactured foods and drinks as an emulsifier, humectant, sweetener, low-energy filler or thickening agent, and preservative.
• Glycerol is also used in the pharmaceutical industry to make soaps, toothpaste, cough syrups, creams and lotions.
• Pure glycerol exists as a clear and very viscous non-hazardous liquid that is highly soluble in water.

1. Pre-exercise hyperhydration

Pre-exercise hyperhydration is a state of elevated body water induced acutely prior to exercise by means of fluid ingestion with or without waterbinding agents, such as Glycerol⁴.

Glycerol-induced hyperhydration may be used to increase the athlete’s capacity to tolerate fluid loss and offset (i.e., delay, prevent or attenuate) the deleterious effects of dehydration (e.g., fluid loss >2% BM) that can occur during exercise⁵ . This strategy may be beneficial in a range of challenging situations that commonly arise in sport, such as:

• When preparing for competition in which high fluid losses are anticipated through prolonged exposure to hot environments or when it is not possible for fluid intake to match sweat losses.
• For athletes competing in sports where fluid consumption is impractical, such as during the swim-leg of an Ironman (World Triathlon Corporation) Triathlon race or during tournament-style of play in team sports, where matches are played in close succession over a day and there is limited time between matches to replace fluid loss.
• When competition regulations limit an athletes access to fluids, for example tennis or football (soccer) match play.
• Avoiding the need to drink during competition for example, maintaining a streamline position in a cycling time trial or avoiding an adjustment in the race line during a marathon such that the onset of the fluid intake is postponed.
• When an athlete’s voluntary fluid intake is reduced because of gastrointestinal distress or a reduced drive to drink.

The benefits associated with pre-exercise hyperhydration can be put into perspective when the consequences of dehydration (i.e., increase in body core temperature and thermal strain) during exercise can negate the physiological advantages resulting from increased fitness and heat acclimatization.⁶

How is pre-exercise hyperhydration achieved?

Compared to hydrating with water, adding effective osmotic agents such as glycerol (and sodium; for more information, refer to ‘Electrolytes’) to a hydration solution will lower urine production and thus increase fluid retention² . Accrued fluid retention with glycerol is possible through Glycerol’s direct effect on reabsorbing fluid through the kidneys.⁷ Specifically, glycerol is reabsorbed by the kidney tubules, increasing the concentration gradient of the renal medulla, thereby water reabsorption in the nephron is enhanced.⁸

Since glycerol and sodium enhance fluid retention through different physiological mechanisms, sodium can also be added to glycerol hyperhydration solution because their combination can be more effective than either osmolyte alone. The following diagram illustrates the fluid retention achieved through three common hyperhydration strategies adapted from previous work conducted.^2,3

Figure 1. Comparative effects of different hyperhydration solutions on fluid retention. WIH – Water-induced hyperhydration, GIH – Glycerolinduced hyperhydration, SIH – Sodium-induced hyperhydration, G+SIH – Glycerol + Sodium-induced hyperhydration.

How and when do I hyperhydrate with glycerol?

Effective protocols of Glycerol-induced hyperhydration include the addition of 1.2 - 1.4 g/kg body mass Glycerol in ~25 ml/kg body mass fluid in the 90 - 180 min prior to exercise.¹ For example, a 75 kg athlete would weigh out 90 – 105 g glycerol on a set of calibrated kitchen scales and add their fluid of choice (i.e., 1875g water, cordial or sports drink).

As an alternative hyperhydration strategy, the addition of 3.0 g/L sodium, with or without glycerol, can be added to a hydration solution.³ To maintain palatability, an electrolyte supplement may be appropriate

What to expect?

• When ingested orally, glycerol is rapidly absorbed and distributed throughout the body’s fluid compartments, until it is gradually excreted over the next 24 - 48 h.
• In terms of the timing with other pre-event activities (e.g., warm up, marshalling duties, final preparations), peak urine production is likely to occur 60 - 80 min after ingestion.
• Greater fluid retention for up to 4 h after ingestion.
• Reduced urinary volume that is more concentrated.
• Compared to other hyperhydration strategies, the additional of glycerol to a solution is well tolerated with low abdominal discomfort.
• When combining glycerol and sodium-induced hydration strategies, you should expect to see lower urine production and greater fluid retention compared with glycerol-induced hyperhydration on its own.
• When compared to pre-exercise euhydration, pre-exercise hyperhydration has been shown to reduce dehydration-induced increases in heart rate and heat storage.

2. Post-exercise hydration

Post-exercise rehydration strategies should aim to correct fluid and electrolyte losses accumulated during an event to enhance recovery and subsequent performance in training and/or competitions held over consecutive days. Under circumstances that limit time or prevent the consumption of meals or snacks that facilitates complete fluid balance restoration, glycerol may be used and offers the following benefits:

• reduced diuresis associated with rehydration. In the case of rehydrating after exercise performed late in the day, glycerol-induced rehydration can reduce overnight diuresis to avoid interruptions to the athlete’s sleep patterns.
• aggressive rehydration after weigh-in where weight-making practices (e.g., dehydration) have been implemented to achieve a target weight in weight-division sports.

How and when do I hydrate with glycerol after exercise

The volume required to restore fluid balance will depend on the net deficit from sweat loss during the previous exercise bout. As a general guide, it may be necessary to drink up to 150% of weight loss.⁴

Add 1.0 g/kg body mass of glycerol to each 1.5 L fluid consumed.⁹

Glycerol can be purchased in Australia from supermarkets, pharmacies, and chemists under the name of glycerine. The cost is less than $AUD10 for 200 ml.

It should be noted that the description on the bottle can cause confusion, as it is listed for use as an emollient to soften roughened skin. Glycerol is safe to ingest according to the recommendations provided herein.

The ergogenic nature of glycerol has been investigated according to its effect on fluid retention, which has been shown to positively influence thermoregulatory function, cardiovascular responses and, hence, athletic performance.

Research on impact of glycerol on thermoregulation and performance have provided mixed results but some studies, including trials conducted at the AIS, have shown benefits to performance of moderate-high intensity exercise performed in the heat.

A meta-analysis concluded that the use of glycerol-induced hyperhydration in hot conditions provided a small (3% power output, effect size 0.35) but worthwhile enhancement to prolonged exercise performance above hyperhydration with water.

Glycerol was formally removed from the World Anti-Doping Agency (WADA) Prohibited List on 1st January 2018. Glycerol is, therefore, currently a permitted substance for use in high-performance sport.

Pre-exercise hyperhydration strategies involving glycerol supplementation need to be practiced in determining their effectiveness for individuals under real-life sorting scenarios. As such, the effectiveness of glycerol hyperhydration or rehydration strategies may depend upon the environmental conditions and exercise situations.

When used in accordance with the recommended ingestion protocols, glycerol is very safe with a very low prevalence of side-effects, making it relatively safe to use. However, the following concerns and considerations should be considered.

Concerns

• Gastrointestinal discomfort, which can, in turn, impair athletic performance
• The gain in body mass associated with more fluid being retained may create a performance impairment
• Nausea
• Headaches
• Laxative effect

Considerations

• Over and under drinking of fluids can be harmful so athletes should seek the advice of an Accredited Sports Dietitian for individual guidance around the use of glycerol.
• If an athlete is unable to tolerate such large volumes of fluid required to induce pre-exercise hyperhydration then a smaller volume of the same concentration of glycerol solution may be ingested closer to the commencement of exercise.⁹
• There is no physiological (i.e., cardiovascular and thermoregulatory) advantage in performing pre-exercise hyperhydration for athletes who can commence exercise in a euhydrated (i.e., normal state of body water content) state when the ability to drink prevents a fluid deficit within 2% of body mass.¹¹ As this is typically not the case during ultra-enduracne races, glycerol-induced hyperhydration is not recommended prior to such activities and may cause prolonged fluid overloading.
• Most laboratory-based hyperhydration studies have compared and quantified the fluid retention achieved through the ingestion large boluses of flavoured water, with and without the addition of glycerol (and sodium). While water services a scientific study as a good ‘control beverage’, a carbohydrate-electrolyte drink may provide a better hydration potential than water alone.¹²

Optimising an ice-slurry beverage

Improved exercise performance with glycerol may not simply be explained by an attenuated body fluid deficit but may be the result of a reduction in deep body core temperature.

The use of internal pre-event cooling strategies, such as ice-slurries and cold beverages have been shown to increases the athlete’s capacity to store environmental and metabolic heat gained during exercise.

Glycerol’s ability to hydrogen-bond with water means that when a glycerol:water mixture is cooled it lowers the freezing point of the solution before ice starts to form, acting as an ‘anti-freeze’. The addition of glycerol (or other solutes, such as carbohydrate and/or sodium) to a hydration solution allows it to be served at sub-zero temperatures and improves its consistency so frozen beverage can be readily ingested using a straw.¹ A practical limitation may involve the discomfort associated with subsequent brain freeze (i.e., sphenopalatine ganglioneuralgia).

Considerations

• Since the timing of hyperhydration (90-180 min pre-exercise) and pre-cooling (30-60 min pre-exercise) strategies are implemented at different times prior to the start of exercise, the dose of glycerol can be split between the beverages but favouring the timing of delivery of the hyperhydration beverage. For instance, withhold 0.2 - 0.4 g/kg BM glycerol from the glycerol-based hyperhydration to add to the slushie.
• Explicit ingredient labelling is required if adding glycerol to an ice-slurry machine so other users are aware of the contents.

1. McCubbin A, Allanson B, Caldwell J, et al. (2020). Sports Dietitians Australia position statement: Nutrition for exercise in hot environments. Int J Sport Nutr Exerc Metab, 31, 1-16.
2. Savoie FA, Dion T, Asselin A, Goulet ED. (2015). Sodium-induced hyperhydration decreases urine output and improves fluid balance compared with glycerol- and water-induced hyperhydration. Appl Physiol Nutr Metab, 40(1), 51-8.
3. Goulet E, De La Flore A, Savoie F, Gosselin J. (2018). Salt + glycerol-induced hyperhydration enhances fluid retention more than salt- or glycerolinduced hyperhydration. Int J Sport Nutr Exerc Metab, 28(3), 246-252.
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5. Goulet E, Aubertin-Leheudre M, Plante G, Dionne I. (2007). A meta-analysis of the effects of glycerol-induced hyperhydration on fluid retention and endurance performance. Int J Sport Nutr Exerc Metab, 17(4), 391-410.
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9. van Rosendal S, Osborne M, Fassett R, Coombes J. (2010). Guidelines for glycerol use in hyperhydration and rehydration associated with exercise. Sports Med, 40(2), 113-29.
10. Thomas D, Erdman K, Burke L. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics, 116(3), 501-528.
11. Latzka W, Sawka M, Montain S, et al. (1997). Hyperhydration: thermoregulatory effects during compensable exercise-heat stress. J Appl Physiol, 83(3), 860-6.
12. Goulet E. (2009). Review of the effects of glycerol-containing hyperhydration solutions on gastric emptying and intestinal absorption in humans and in rats. Int J Sport Nutr Exerc Metab, 19(5), 547-60.

1. Burke L, Stear S, Lobb A, et al. (2011). A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance—Part 19. British Journal of Sports Medicine, 45, 456-58.
2. Goulet EDB. (2008). Pre-Exercise Hyperhydration: Comments on the 2007 ACSM Position Stand on Exercise and Fluid Replacement. JEPonline, 11(2), 64-74.