Sports Nutrition

Summary of Recommendations and Evidence


 
This Summary of Recommendations and Evidence synthesizes the Key Practice Point(s) for each Practice Question (PQ) in this Knowledge Pathway. It is organized by the Nutrition Care Process and contains statements or recommendations that have been graded using either the PEN or GRADE approaches to critical appraisal. For additional information on the evidence and references, see the PQs in this Knowledge Pathway. 
 
As part of the PEN evidence synthesis process, the research in an area is reviewed, as well as various national recommendations. The most recent national recommendations do not typically supersede other evidence, as these recommendations are country-specific. PEN recommendations are based on evidence. Government agencies' recommendations are based on their assessment of the evidence in light of the populations served, risk and their ability to implement and monitor recommendations. These recommendations may not be based on a rigorously conducted systematic review. Country-specific recommendations, as well as PEN’s synthesis of the best evidence, are presented in the Key Practice Point for the PEN user to use at their discretion.

Content
  1. Electrolyte Beverages
  2. Safety of Creatine, Caffeine or Protein Supplements
  3. Higher Carbohydrate Diets Effectiveness Versus Lower Carbohydrate Diets
  4. Optimal Timing and Composition of a Pre-exercise Meal
  5. Optimal Timing and Amount of Carbohydrate During Exercise
  6. Optimal Timing and Composition of a Meal to Support Recovery
  7. Alcohol Consumption Post-exercise Recovery
  8. Dietary Strategies To Treat Relative Energy Deficiency in Sport
  9. Vegetarian Diets Versus Omnivorous Diets to Support Athletic Performance
  10. High Protein Plant-based Diets to Increase Muscle Mass
  11. Iron Deficiency in Vegetarian Athletes

1. Electrolyte Beverages
Sports Drinks (With or Without Caffeine)
Recommendation
Sports Drinks Without Caffeine

For healthy young adults performing endurance activities (e.g. cycling, running), hypotonic sports drinks (<275 mOsmol/kg) consumed throughout exercise may hydrate better than iso- and hypertonic sports drinks or water.

Water is the best beverage for children and youth engaging in routine physical activity and play-based activities, although sports drinks may be appropriate for children and youth participating in physical activity lasting longer than one hour and/or when activities take place under hot, humid conditions.

Energy Drinks and Sports Drinks with Caffeine
Sports or energy drinks containing 3 mg/kg body weight of caffeine probably improve athletic performance in healthy, active adolescents and adults compared to taste-matched, non-caffeinated drinks. Adverse effects are not known.

Evidence Summary
A 2022 meta-analysis of 28 trials (n=210 male, n=16 female; average age 26.3 years) involving a mixture of healthy non-athletes and well-trained cyclists and runners found that consuming a hypotonic carbohydrate-electrolyte beverage (<275 mOsmol/kg, <50 mmol/L sodium) during continuous exercise hydrated better than isotonic beverages (275 to 300 mOsmol/kg) and most likely hydrated better than either hypertonic beverages (>300 mOsmol/kg) or water (<40 mOsmol/kg). Results may be limited by the small sample size and limitations associated with the use of percent change in plasma volume to measure hydration status.
Grade of Evidence C

A 2021 systematic review of 37 RCTs (n=692 healthy, active participants aged 12 to 45 years with varying levels of habitual caffeine intake) found that consuming sports or energy drinks with at least 3 mg caffeine per kilogram body weight improved various measures of athletic performance (e.g. endurance, muscle performance, sprinting, specific sport-based skills) across a variety of sports (e.g. cycling, soccer, swimming, racquet sports) compared to taste-matched, non-caffeinated placebo drinks. Adverse effects of caffeine were not studied. Results may be limited by the small sample size of most of the included studies and potential confounding of other ingredients in the beverages (carbohydrates, electrolytes).
Grade of Evidence B

The 2017 position statement from the Nutrition and Gastroenterology Committee of the Canadian Paediatric Society, which was reaffirmed in 2023, states that water is the best beverage for children and youth engaging in routine physical activity and play-based activities. Sports drinks may be appropriate hydration beverages for children and youth participating in physical activity lasting longer than one hour and/or in activities that take place under hot, humid conditions.
Grade of Evidence C
 
Remarks
Sports drinks are beverages that contain carbohydrates and electrolytes and increasingly may contain caffeine. Energy drinks are beverages that contain caffeine, carbohydrates, taurine and B vitamins, sometimes in combination with electrolytes or herbal ingredients.
 
Hypotonic sports drinks contain carbohydrates and electrolytes in lower concentrations than human body fluids (i.e. <275 mOsmol/kg). They help maintain hydration during exercise by increasing blood volume and reducing diuresis. Caffeine may improve athletic performance because it reduces the level of pain and exertion the athlete experiences.
 
The single safe dose of caffeine for healthy adults, children and adolescents is 3 mg/kg body weight. Consuming too much caffeine can disrupt sleep, cause anxiety and is associated with cardiovascular problems. 
 

Coconut Water
Recommendation
The evidence suggests that there is probably little to no difference between consuming coconut water or plain water on hydration status or athletic performance in healthy, physically active predominantly male adults. Results may not be applicable to other populations.

Evidence Summary
A 2023 systematic review of four RCTs (n=42 healthy, physically active adults, 95% male) found no statistically significant differences between coconut water and plain water on measures of hydration status (i.e. cumulative urine output, net fluid balance, plasma volume change, serum osmolality, plasma osmolality, serum sodium concentration) within two hours of exercise. Adverse events included gastric fullness and nausea but were generally not different between intervention and control groups.

In a randomized crossover trial published after the systematic review, 19 cyclists (15 male, 4 female; aged 30±9 years, V02peak 55±8 mL/kg/min) with at least three years cycling experience consumed either coconut water with added carbohydrates and sodium (1420 mg/L potassium, 448 mg/L sodium, 66 g/L carbohydrate) or a commercially available sports drink (132 mg/L potassium, 458 mg/L sodium and 55 g/L carbohydrate) in a dose of 2.5 mL/kg body weight during an exercise protocol that involved a pre-load phase where participants cycled at 65-75% peak power for 90 minutes interspersed with five, five-minute higher intensity periods and then a 20 km time trial. There was no statistically significant difference between groups for any of the performance outcomes (i.e. glucose, lactate, sweat loss, heart rate, time or power). Findings may be limited by the small sample sizes, the addition of sodium and carbohydrates to the coconut water and that the pre-load phase did not induce dehydration.
Grade of Evidence C
 
Remarks
Each component of an oral rehydration solution plays a different role in hydration. Sodium increases thirst and fluid retention and increases palatability of the beverage. Both sodium and potassium replace what is lost through sweat. Carbohydrates and flavour improve palatability and promote intake.

2. Safety of Creatine, Caffeine or Protein Supplements
Creatine Supplements
Recommendation
Exercise Performance

Taking 20 to 23 g of creatine supplements per day in combination with carbohydrates for three to seven days probably increases sprint power in cycling in young adult males. Creatine supplements on their own probably do not affect other measures of sprint performance or affect endurance performance in trained, young adult males. Evidence in females and gender-diverse athletes is lacking.

Body Fat Percentage
Creatine supplements (2 to 20 g/day or 0.03 to 0.3 g/kg/day) taken for at least four weeks probably reduces body fat percentage by about 1% in males <50 years but probably does not affect absolute fat mass. Evidence in females and gender-diverse athletes is lacking.

Recovery After Exercise
Creatine supplements may not affect recovery up to 96 hours after exercise in young male adults. Evidence in females and gender-diverse athletes is lacking.

Safety
Creatine supplements taken in doses between 1 and 30 g/day for up to one year are probably safe for post-pubescent, non-pregnant females. Adverse events were not discussed in the evidence involving males.

Evidence Summary
Exercise Performance
A 2023 systematic review and meta-analysis of 13 trials mainly of good or excellent quality involving 277 trained athletes (mostly young adult males) found that creatine supplements administered for five to 70 days in doses ranging from 5 to 10 g/day in either a loading or maintenance protocol had no impact on endurance performance compared to placebo. Adverse events were not discussed. Results may not be generalizable beyond young adult male endurance athletes.
Grade of Evidence B

A 2022 meta-analysis of 14 high quality RCTs involving 320 young adults (4.3% female) found that creatine supplements administered in doses between 20 and 23 g/day (usually in combination with carbohydrates, although the type of carbohydrate was not specified) for three to seven days increased body mass by 0.79 kg and mean power for sprint cycling by 0.82 W but had no impact on peak power output, mean power output for sprint running, fatigue or posttest blood lactate. Adverse events were not discussed. Results may be limited by the small sample sizes and the low number of studies included in some of the meta-analyses.
Grade of Evidence B

Body Fat Percentage
A 2023 systematic review and meta-analysis of 12 RCTs (n=266 adults <50 years with various levels of training, mostly males) of mostly moderate and low risk of bias found that, compared to resistance training alone, resistance training in combination with creatine supplements administered in either absolute or relative doses of 2 to 20 g/day and 0.03 to 0.3 g/kg/day, respectively, for at least four weeks reduced body fat percentage by 1.19% but did not reduce absolute fat mass. Subgroup analysis did not change these results. Adverse events were not discussed. The different tools used to assess body fat and the varying levels of training status of the study participants may limit these findings.
Grade of Evidence B

Recovery After Exercise
A 2021 meta-analysis of 13 RCTs with low or unclear risk of bias involving 278 adults (15% female) with varying levels of training found that creatine supplements administered in doses of 10 to 20 g/day or 0.3 g/kg/day for five to six days reduced creatine kinase activity at 48 hours post-exercise (but not at other time points and with significant heterogeneity at 72 and 96 hours post-exercise). It had no effect on muscle strength recovery time, muscle soreness, lactate dehydrogenase activity, range of motion or measures of inflammation and oxidative stress at any timepoint up to 96 hours post-exercise. Adverse events were not discussed. Findings may be limited by the small number of studies included in each of the meta-analyses, which prevented subgroup analysis, the variation in level of training between study participants and that most of the study participants were male.
Grade of Evidence C

Safety
A 2020 systematic review and meta-analysis of 29 studies (mostly RCTs) mainly with a low or unclear risk of bias involving 951 post-pubescent, non-pregnant females found no difference in the rate of adverse events between individuals taking creatine supplements (1 to 30 g/day for four days to one year) and those taking the placebo. Gastrointestinal side-effects (e.g. nausea, vomiting, bloating) were the most common side-effects in both groups.
Grade of Evidence B
 
Remarks
Most studies administered creatine supplements in higher doses for a few days (loading phase), followed by lower doses for several days or weeks (maintenance phase).

Creatine can promote faster recovery of intramuscular phosphocreatine between sprints, which may result in an increase in mean power output for cycling.

Creatine supplements can increase body mass, enhance muscle hypertrophy and enlist fast twitch muscle fibres, which may negatively impact endurance.

Caffeine Supplements
Recommendation

Exercise Performance

Caffeine supplements (e.g. capsules, powder, solutions, gum) administered in doses ranging from 1.3 to 10 mg/kg body weight between 15 and 60 minutes before exercise probably improve exercise performance in athletes participating in combat sports (e.g. martial arts) and women participating in team sports (e.g. basketball, volleyball, rugby, softball). Caffeine supplements administered up to 60 minutes before exercise in doses between 4 and 6 mg/kg body weight, but potentially as low as 1 to 2 mg/kg body weight, probably improves strength training performance in healthy young adults.

Caffeine supplements may not improve athletic performance or the cognition of soccer players of any level, but caffeine appears to be safe.

Recovery After Exercise
Caffeine supplements administered in doses ranging from 1 to 6 mg/kg body weight either before or after exercise may slightly reduce muscle soreness and aid in recovery.

Evidence Summary
Exercise Performance 
Several meta-analyses have examined the effect of caffeine on the performance of athletes engaged in various sports.
  • Soccer: a meta-analysis of 16 RCTs (n=241, mix of amateurs and professionals) mainly with an unclear risk of bias found that caffeine supplements administered 30 to 90 minutes before exercise in doses ranging from 1 to 6 mg/kg body weight had no significant effect on any measure of athletic performance or cognition compared to placebo. Adverse events did not differ between the intervention and control groups. Grade of Evidence C
  • Combat Sports: a meta-analysis of 25 RCTs (n=301 judo, taekwondo, wrestling, jiu-jitsu, boxing and karate athletes, 11% female) mainly with a low risk of bias found that caffeine supplements administered 15 to 60 minutes before exercise in doses ranging from 2.7 to 10 mg/kg body weight had a statistically significant ergogenic effect on vertical height jump, reaction time, number of throws and both number and duration of offensive actions compared to placebo. Adverse events were not discussed. Grade of Evidence B
  • Team Sports: a meta-analysis of 18 trials (n=240 basketball, volleyball, soccer, rugby, handball, softball, hockey, netball athletes, 100% female) mainly with a low risk of bias and of good or excellent methodological quality found that caffeine supplements administered 30 to 70 minutes before exercise in doses ranging from 1.3 to 6 mg/kg body weight had a statistically significant ergogenic effect on intensity of total body impacts, sport drills, countermovement jumps and handgrip compared to placebo, but not on other measures of athletic performance. Most studies required participants to abstain from caffeine in the 48 hours preceding the study. Adverse events were not discussed. Grade of Evidence B
  • Strength Training: a meta-analysis of 19 trials mainly with a low risk of bias found that caffeine supplements administered 30 to 90 minutes before exercise in doses ranging from 4 to 6 mg/kg body weight had a statistically significant ergogenic effect on muscle endurance and maximum strength for the bench press exercise compared to placebo, but not the leg press exercise. Most studies required participants to abstain from caffeine for between six hours and seven days before the study. Adverse events were not discussed. Grade of Evidence B

The 2021 position statement from the International Society of Sports Nutrition (ISSN) states that caffeine (dose not specified):
  • improves athletic performance in both trained and untrained individuals
  • provides moderate-to-large benefits to aerobic performance, although results can vary between individuals
  • offers small-to-moderate improvements to various aspects of athletic performance (e.g. sprinting, jumping, sport-specific actions and muscular endurance and strength) in many, but not all, studies
  • improves exercise performance in doses ranging from 3 to 6 mg/kg body weight and is associated with adverse events in doses >9 mg/kg body weight with no additional ergogenic benefit
  • is most often consumed 60 minutes before exercise, although the optimal timing of ingestion may depend on the source (e.g. beverage, powder, gum)
  • improves cognitive function (e.g. attention, vigilance) in most individuals.
Grade of Evidence C

Recovery After Exercise
A meta-analysis of seven trials (n=104 healthy young adults, 39% female) with a high risk of allocation concealment bias and unclear risk of bias for sequence generation found that caffeine supplements administered either before or after exercise in doses ranging from 1 to 6 mg/kg body weight had a statistically significant ergogenic effect on uscle soreness 48 hours after exercise (but not at other time points) and creatine kinase activity immediately post-exercise (but not at other time points). Adverse events were not discussed.
Grade of Evidence C

Minimum Dose
Results from a 2022 meta-analysis of 12 high quality RCTs (n=206 participants, 43% female) suggest that caffeine from supplements (e.g. capsule, solution, gel) or coffee in doses as low as 0.9 to 2 mg/kg body weight consumed up to 60 minutes before strength training improves muscular strength, endurance and velocity. Findings may not be generalizable beyond healthy, young adults.
Grade of Evidence B
 
Remarks
Caffeine may improve athletic performance by stimulating the central nervous system, mobilizing calcium in muscles to aid muscle contraction or by optimizing metabolism during exercise.
 
Caffeine in doses ranging from 400 to 500 mg/day is generally safe for adults. Too much caffeine can cause insomnia, restlessness, nausea, vomiting and heart problems (e.g. tachycardia, arrhythmia) and taking more than 10 to 14 g (150 to 200 mg/kg body weight) of pure caffeine in one sitting increases the risk of death.
 

Protein Supplements
Recommendation
Exercise Performance and Lean Body Mass
Protein supplements (type not specified by researchers) administered immediately before or after exercise may improve aerobic capacity and slightly increase lean body mass in adults participating in endurance activities.
 
Recovery After Exercise
Protein supplements, including whey (with or without carbohydrates), milk-based, combination supplements (e.g. whey, casein and collagen), pea, egg and soy (0.3 g to 1.5 g/kg body weight or 6 to 42 g) and branched-chain amino acid (BCAA) supplements (100 to 450 mg/kg body weight or 6 to 20 g) taken before or after resistance exercise probably improve recovery in male young adults. Evidence in females and gender-diverse athletes is lacking. 
 
Evidence Summary
A 2023 meta-analysis of 29 trials (n=763 adults, 94% male) mostly of excellent or good quality involving a mixture of trained and untrained young adults found that liquid whey protein (with or without carbohydrates), milk-based supplements or other protein supplements (e.g. combination of whey, casein and collagen, pea protein, egg white, soy protein) taken in relative doses of 0.3 g to 1.5 g/kg body weight or absolute doses 6 to 42 g immediately before or after resistance exercise help preserve muscle strength (i.e. isometric and kinetic maximal voluntary contraction) and lower creatine kinase activity in young adult males but do not affect muscle soreness. Results may be limited by the different supplementation doses and strategies used in the studies, the use of non-isoenergetic controls and potential error during the data extraction stage of the study. Results may not be applicable to older adults or females.
Grade of Evidence B

A 2022 meta-analysis of 25 trials (n=479, mostly young adult males) mainly of good or excellent methodological quality involving both trained and untrained participants found that BCAA supplements administered before or after exercise in either relative or absolute doses of 100 to 450 mg/kg body weight and 6 to 20 g/day, respectively, reduced biomarkers of muscle damage (e.g. creatine kinase, lactose dehydrogenase, myoglobin) 48 hours after exercise, but not 24 hours after exercise, and decreased delayed onset muscle soreness at 24 and 48 hours after exercise as measured by a visual analogue scale. BCAA supplements had no effect on muscle performance. Higher doses of BCAA supplements (amount not specified by study authors) predicted biomarkers of muscle damage. Results may be limited by the small sample sizes and may not be generalizable beyond young male adults.
Grade of Evidence B

A 2021 meta-analysis of 19 trials (of mixed quality and many with unclear or high risk of bias) involving 1162 adults found that protein supplements (type not specified) containing between 10 and 84 g protein/day or between 3 and 18 g essential amino acids/day consumed either immediately before or after endurance training for 4.5 to 24 weeks improved aerobic capacity, as measured by peak oxygen uptake (VO2 peak) and workload power (WPEAK), increased lean body mass and improved performance of timed trials. Results may be limited by small sample sizes, lack of assessment of habitual protein intake and heterogeneity of study populations (including non-athlete populations) and exercise protocols (including some that combined endurance and resistance training).
Grade of Evidence C

Remarks
Consuming protein after exercise stimulates muscle protein synthesis. BCAAs have anabolic and anti-catabolic properties that may lessen the amount of exercise-induced muscle damage.
 
The International Society for Sports Nutrition (ISSN) states that 1.4 to 2.0 g/kg/day protein is enough for most individuals who exercise. For resistance- trained individuals, the ISSN recommends consuming between 2.3 and 3.1 g/kg fat-free mass/day during times of hypocaloric intake and consuming >3 g/kg/day protein to promote fat loss.
 

3. Higher Carbohydrate Diets Effectiveness Versus Lower Carbohydrate Diets
Aerobic Exercise Performance
Recommendation
Higher carbohydrate diets are probably not more effective than lower carbohydrate diets at improving aerobic exercise performance in healthy adults participating in endurance activities.

Strategically altering carbohydrate intake to enable a shift to fat oxidation may improve the endurance performance of ultra-marathon runners, but training in a chronically glycogen deprived state is not advised.

Evidence Summary
Results from a 2021 systematic review and meta-analysis of 10 small trials (n=5 to 24 participants/trial) conducted in adults (<50 years, mostly males) suggest that low carbohydrate ketogenic diets (≤10% carbohydrate, ≥60% fat) followed for up to 12 weeks reduced respiratory exchange rate (SMD -1.81) compared to higher carbohydrate diets but did not alter VO2 max, time to exhaustion, maximum heart rate or rating of perceived exertion. Results may be limited by small sample sizes, short study durations and the lack of measurement of race times in real-world competitions. Results may not be generalizable beyond healthy male adults.
Grade of Evidence C

The 2019 position statement on nutritional considerations for training and racing in ultra-marathons from the International Society of Sports Nutrition states that:
  • A macronutrient breakdown of 60% carbohydrates (7 to 10 g/kg/d), 15% protein (1.3 to 2.1 g/kg/d) and 25% fat (1.0 to 1.5 g/kg/d) is required for endurance training Grade of Evidence C.
  • There is not enough evidence to support the use of high fat ketogenic diets for ultra-marathon training Grade of Evidence C.
  • Altering carbohydrate intake to strategically enable metabolic adaptations (i.e. a shift to fat oxidation) may improve endurance performance, but training in a chronically glycogen deprived state is not advised Grade of Evidence B.
 
Strength Training Performance
Recommendation
Higher carbohydrate diets are probably not more effective than lower carbohydrate diets at improving strength training performance in healthy adults.

Evidence Summary
A 2023 systematic review of 17 studies (mostly RCTs) conducted in healthy adults (mostly male) aged 29±8 years found that there was no significant difference in strength training performance (e.g. maximal strength, training volume to failure) between individuals following higher carbohydrate (average carbohydrate intake 330 g/day, 49% total energy intake) and lower carbohydrate diets (average carbohydrate intake 100 g/day, 17% total energy intake) for up to three months. Results may be limited by the overlap in carbohydrate intake between the lower and higher carbohydrate diet conditions, small sample sizes and the short duration of the studies. Results may not be applicable to females.
Grade of Evidence B

A 2021 systematic review of five small trials (mostly of poor methodological quality) conducted in healthy adults found no difference in CrossFit performance (e.g. number of repetitions, vertical jump) between individuals consuming a higher carbohydrate (>50 g carbohydrate/day) and lower carbohydrate diet (≤50 g carbohydrate/day) for up to three months. Results may be limited by the small sample sizes, short study durations and the lack of assessment of glycogen levels and control of dietary intake.
Grade of Evidence C
 
Remarks
Eleven of the studies included in the systematic review described the low carbohydrate diet condition as a ketogenic diet and all but one of these studies restricted carbohydrate intake to less than 50 g per day.
 
CrossFit is a high intensity, functional workout that can increase heart rate to an average of 90% of maximum heart rate.
 

Additional Remarks
It is hypothesized that because CrossFit is a high intensity activity, glycogen levels would drop quickly, making carbohydrate essential for performance but this has not been confirmed by the evidence.

4. Optimal Timing and Composition of a Pre-exercise Meal
Recommendation
Limited evidence suggests that consuming carbohydrates before exercise may improve athletic performance in young adult male endurance athletes when exercising for more than 90 minutes, but the evidence in females and gender-diverse athletes is lacking. The following nutritional strategies can be considered:
  • Consume either nothing or 10 to 30 g of protein before performing low to moderate intensity exercise for less than 90 minutes when starting muscle glycogen is low or normal.
  • Consume between 0 and 75 g of carbohydrates and/or 10 to 30 g of protein before performing high intensity exercise for less than 90 minutes when starting muscle glycogen is normal.
  • Consume up to 75 g of carbohydrates and/or 10 to 30 g of protein before performing low to moderate intensity exercise for more than 90 minutes when starting glycogen is low or normal.
  • Consume between 75 and 150 g of carbohydrates and 10 to 30 g of protein before performing high intensity exercise for more than 90 minutes when starting muscle glycogen is normal or high.
 
Evidence Summary
Results from a 2020 narrative review of different pre-exercise nutrition strategies on the athletic performance of young adult male endurance athletes suggest that athletes should consume:
  • either nothing (i.e. fasted state) or 10 to 30 g of protein if they have low or normal muscle glycogen levels and will be performing low or moderate intensity exercise for less than 90 minutes
  • between 0 and 75 g of carbohydrates and/or 10 to 30 g of protein if they have normal muscle glycogen levels and will be performing high intensity exercise for less than 90 minutes
  • less than 75 g of carbohydrates and 10 to 30 g of protein if they have low or normal muscle glycogen levels and will be performing low or moderate intensity exercise for more than 90 minutes
  • Between 75 and 150 g of carbohydrates and 10 to 30 g of protein if they have normal or high muscle glycogen levels and will be performing high intensity exercise for longer than 90 minutes.
Grade of Evidence C
 
Remarks
Fasting overnight reduces liver glycogen but not muscle glycogen.
 
See Additional Content: 

5. Optimal Timing and Amount of Carbohydrate During Exercise  
Endurance Exercise
Recommendation
Liquid carbohydrate supplements with ≤20% carbohydrate probably improve athletic performance in young adult male endurance athletes and probably provide the most benefit when endurance exercise lasts between one and four hours and when consumed during the endurance activity. Evidence in female and gender diverse athletes is lacking.

Evidence Summary
A 2021 meta-analysis of 142 trials (n=3094 adults, mostly males), most of which had a high risk of bias, found that, compared to placebo, liquid carbohydrate supplements (≤20% carbohydrate provided in either a solution or as beverage) improved athletic performance in endurance athletes (e.g. cyclists, runners), with no differences between carbohydrate concentrations, doses, types, formulations or administration frequencies. Subgroup analysis showed that liquid carbohydrate supplements had greater benefit on athlete performance when the endurance exercise lasted between one and four hours (compared to exercise that lasted less than one or more than four hours) and when the supplement was consumed during the activity (compared to before or at the onset of exercise). Most studies were conducted in a lab and may not be reflective of real-world conditions. Findings may not be applicable to female athletes or to other forms of carbohydrate supplements (e.g. gels).
Grade of Evidence B
 
Remarks
Carbohydrates provide energy and help replenish muscle glycogen that is depleted during endurance and resistance exercise.
 
See Additional Content:

Resistance Exercise
Recommendation

Carbohydrates may improve resistance training volume in young adult male athletes, especially when resistance training sessions are 45 minutes or longer, and probably provide the most benefit following an eight hour (or longer) fast. Evidence in females and gender diverse athletes is lacking.

Evidence Summary
A 2022 systematic review and meta-analysis of 21 crossover studies (n=226 participants aged 20 to 30 years, 94.7% male) found that, compared to placebo, carbohydrate ingestion improved total resistance training volume Grade of Evidence C. Subgroup analysis showed that carbohydrates provided the most benefit when resistance training sessions were longer than 45 minutes Grade of Evidence C and when consumed after at least an eight hour fast Grade of Evidence B.
 
Remarks
Total resistance training volume is typically defined as the number of repetitions completed until muscle failure.
 
Carbohydrates provide energy and help replenish muscle glycogen that is depleted during endurance and resistance exercise.
 
See Additional Content:

6. Optimal Timing and Composition of a Meal to Support Recovery
Recommendation
Muscle Glycogen Resynthesis
Consuming 1.02 g/kg/hour of carbohydrates after exercise probably increases the rate of muscle glycogen resynthesis during short recovery periods (i.e. ≤8 hours) in adult male athletes. Co-ingestion of carbohydrates and proteins probably does not impact the rate of muscle glycogen resynthesis during shorter recovery periods. Evidence in females and gender diverse athletes is lacking.
 
Athletic Performance
Co-ingestion of carbohydrates and proteins (e.g. whey, casein, milk or plant-based protein) in ratios of either 4:1, 3:1 or 2:1 after exercise probably improves the athletic performance (e.g. time to exhaustion) of male athletes who cycle or run when the recovery period is at least eight hours, but probably has no impact on athletic performance when the recovery period is eight hours or less.
 
Consuming chocolate milk may increase time to exhaustion compared to plain water, flavoured water or sweetened drinks and may reduce blood lactate compared to other beverages that contain a mixture of carbohydrates, proteins and fats after exercise in adult male athletes. 
 
Evidence in females and gender-diverse athletes is lacking.
 
General Nutrition Advice to Support Recovery
Appropriate nutritional approaches to rehydrating, refuelling and repairing after exercise are athlete-specific and are influenced by a variety of factors. General advice for the recovery phase is:
  • Fluid: 150% (1.5 L/kg) weight lost during exercise using a fluid that contains between 20 and 30 mEq/L sodium when the recovery period is less than four hours and between 40 and 60 mEq/L sodium when there is very little time between training sessions or if the athlete is moderately dehydrated
  • Carbohydrates: 5 to 8 g of carbohydrate/kg for moderate duration, low intensity training, 8 to 10 g of carbohydrate/kg for moderate to heavy endurance training and 10 to 12 g of carbohydrate/kg for extreme exercise
  • Proteins: 0.5 g/kg of high quality protein (absolute dose 40 g) during the recovery phase. 

Evidence Summary
A 2021 systematic review and meta-analysis of 29 controlled trials (n=246 healthy adults, mostly males) found that, compared to water or non-nutritive interventions, consuming 1.02 g/kg/hour of carbohydrate after cycling, running or resistance training for varied durations or performed to exhaustion increases the rate of muscle glycogen resynthesis during short recovery periods (i.e. eight hours or less) and that improvements to the rate of muscle glycogen resynthesis are highest when carbohydrate is consumed at least hourly after exercise. Consuming protein in addition to carbohydrate did not affect the rate of muscle glycogen resynthesis during short recovery periods. Results may not be generalizable to females.
Grade of Evidence B

A 2020 systematic review and meta-analysis of 14 trials with mainly low and unclear risk of bias involving healthy adults (n=130, mostly males) found that the co-ingestion of carbohydrates and protein (e.g. whey, casein, milk or plant-based protein) in ratios of either 4:1, 3:1 or 2:1 during the recovery period after cycling or running improved the subsequent time to exhaustion when the recovery period was longer than eight hours but not when it was shorter than eight hours. Results may not be generalizable to females.
Grade of Evidence B

A 2019 systematic review and meta-analysis of 12 RCTs (n=130 athletes; mostly males) of mostly fair quality found that 236 to 1000 mL of chocolate milk did not affect time to exhaustion, rating of perceived exertion, blood lactate, serum creatine kinase or heart rate compared to controls. Subgroup analysis showed that chocolate milk increased time to exhaustion by 0.78 minutes compared to placebo beverages (i.e. plain water, flavoured water, sweetened drinks) and by 6.13 minutes compared to other beverages containing a combination of carbohydrates, proteins and fats (macronutrient breakdown not reported) and reduced blood lactate compared to placebo beverages. Results may be limited by the lack of high quality research on this topic, the different methods used to measure some of the outcomes, and may not be generalizable to females.
Grade of Evidence C

A 2020 narrative review discussed nutritional strategies to support recovery after exercise in athletes.
  • Rehydration: athletes should generally aim to replenish 150% (1.5 L/kg) weight lost during exercise with a fluid that contains between 20 and 30 mEq of sodium when the recovery period is less than four hours and between 40 and 60 mEq/L of sodium when there is very little time between training sessions or if the athlete is moderately dehydrated. 
  • Refuel: Generally, athletes should consume 5 to 8 g of carbohydrate/kg for moderate duration, low intensity training, 8 to 10 g of carbohydrate/kg for moderate to heavy endurance training and 10 to 12 g of carbohydrate/kg for extreme exercise.
  • Repair: Generally, athletes should consume 0.5 g/kg of high quality protein (absolute dose 40 g) during the recovery phase and between 0.25 and 0.4 g of protein/kg body weight at meals (absolute dose 20 g).
  • Rest: Sleep help supports recovery from exercise, but high quality evidence about nutritional strategies to support sleep in athletes is currently lacking.  
Appropriate approaches to rehydrating, refuelling and repairing are athlete-specific and are influenced by many factors (e.g. exercise intensity and duration, the amount of time between training sessions or competition, the athlete’s total daily energy expenditure and overall dietary intake).
Grade of Evidence C
 
Remarks
Carbohydrates are required for muscle glycogen resynthesis. Ingesting protein during longer recovery periods helps to repair the damage to muscles that occurs during exercise.
 
See Additional Content:

7. Alcohol Consumption and Post-exercise Recovery
Recommendation
Consuming a moderate amount of alcohol (e.g. <1 L of ≈4% beer) within two hours after aerobic or resistance exercise may slightly worsen hydration and reduce muscle protein synthesis but it does not appear to affect other measures of recovery, including muscle soreness or heart rate in healthy young adults. Drinking lower alcohol beer (≤4% alcohol), adding sodium to regular beer and co-ingestion with a nonalcoholic beverage (e.g. water, sports drink) may attenuate diuresis and improve the alcoholic beverage’s ability to hydrate.

Evidence Summary
A 2021 systematic review of 16 studies (mostly randomized crossover trials of fair quality conducted in men ranging from sedentary to professional soccer players) examined the effect of beer on exercise performance, adaptation and recovery. Results suggest that consuming beer with >4% alcohol immediately after exercise modestly worsens fluid balance and hydration (measured by changes to body mass, plasma sodium and potassium, urine specific gravity, urine volume, urine solutes) and that consuming more than 1 L of beer after exercise worsens neuromuscular performance (e.g. balance, reaction time) and choice reaction time but has no effect on muscle strength or endurance. Results also suggest that consuming beer ad libitum over the course of four to 10 weeks does not prevent improvements to VO2 max. Overall, results suggest that lower alcohol beer is better than regular alcohol beer (>4% alcohol) for rehydration after exercise. Additionally, adding sodium to regular alcohol beer may improve its ability to rehydrate and pairing regular alcohol beer with a nonalcoholic rehydration beverage (e.g. water, sports drink) may help counter diuresis. Results may be limited by the small sample sizes, the use of low to moderate intensity exercise in most studies, the potential for bias due to the inability to blind participants and overall differences in study design. Findings may not be generalizable beyond males.

Results from a 2019 systematic review of 12 small crossover trials suggest that consuming alcohol (up to 37.5% alcohol by volume in doses of approximately 1 g/kg body weight) after resistance training may increase cortisol levels and decrease protein synthesis (as measured by the rate of phosphorylation of various enzymes involved in protein synthesis) but that it does not impact other biological measures (e.g. creatine kinase, heart rate and lactate), physical measures (i.e. force, power, muscle endurance, soreness, rate of perceived exertion) or cognitive function in adults (fitness level not specified). The authors concluded that consuming alcohol after resistance exercise does not alter muscle function, although it reduces muscle protein synthesis, which may impair the ability of muscles to adapt over the long term. Results may be limited by the small sample sizes, the omission of patient-centred outcomes and that outcomes were measured soon after exercise, thus long-term effects are not known.

A 2022 crossover trial had 32 healthy young adult participants (n=15 women) perform 25 minutes of moderate intensity running (60-65% maximum heart rate) followed by a one-hour recovery period in which they consumed either 300 mL of 4.5% beer or water in the first 10 minutes. At the end of the recovery period, there was no difference in changes to blood pressure, heart rate or heart rate variability between the two groups. Results may be limited by the lack of blinding and that hydration status was not measured. Findings may not be generalizable to individuals performing higher intensity exercise.
 
Remarks
Beer generally contains around 5% alcohol by volume, although this can vary. Beer may interfere with muscle protein synthesis and promote diuresis. Consuming alcohol after resistance exercise may reduce muscle protein synthesis by decreasing the amount of amino acids in the blood.
 

8. Dietary Strategies To Treat Relative Energy Deficiency in Sport 
Recommendation
Increasing energy and carbohydrate intake, increasing the frequency of meals, decreasing fibre intake, and promoting the consumption of foods that contain micronutrients important for bone building may be effective for treating relative energy deficiency in sport (RED-S) in adult and adolescent athletes.

Evidence Summary
Two narrative reviews discussing the treatment of RED-S in adult and adolescent athletes suggest the following nutritional strategies:
  • Improve energy availability by increasing energy intake, decreasing energy expenditure or both.
  • Minimize the amount of time the athlete spends in energy deficit by adjusting the timing and frequency of energy intake.
  • Increase carbohydrate intake by providing a carbohydrate-rich snack before and after exercise.
  • Consider adjusting fibre intake and promoting the consumption of low fibre, high energy foods instead of high fibre, low energy foods.
  • Take a food-first approach to ensure the adequate intake of micronutrients important for building bones (i.e. protein, calcium, magnesium, phosphorous, vitamin D, potassium, fluoride) but consider supplements if necessary.
Grade of Evidence C
 
Remarks
RED-S is caused by prolonged low energy availability. It can decrease energy metabolism, reproductive function, immunity, glycogen synthesis and musculoskeletal, cardiovascular and hematological health and can negatively impact athletic performance and increase the risk for injury.
 
Athletes (especially adolescent athletes) suspected of having RED-S should be screened for eating disorders and/or disordered eating.
 
Athletes following a vegetarian diet may be at higher risk of RED-S.

Additional Remarks
RED-S is a syndrome of impaired physiological and psychological functioning caused by a prolonged period of energy intake not meeting energy expenditure (called low energy availability) over a prolonged period of time. It is characterized by a decrease in energy metabolism, reproductive function, immunity, glycogen synthesis and musculoskeletal, cardiovascular and hematological health, all of which can negatively impact athletic performance and increase the risk for injury.

9. Vegetarian Diets Versus Omnivorous Diets to Support Athletic Performance
Recommendation
Vegetarian diets may support athletic performance in recreational and elite endurance athletes as well as omnivorous diets. Research on athletes participating in strength-based sports is lacking.

Evidence Summary
Results from a 2021 narrative review and a 2016 systematic review of mostly RCTs suggest that, compared to omnivorous diets, vegetarian diets may be associated with improved cardiovascular health (e.g. reduced blood lipid levels and blood pressure) in recreational and elite endurance athletes but are no better or worse for aerobic or anaerobic capacity, exercise capacity, resistance training, exercise-induced oxidative stress, inflammation, immune response or incidence of upper respiratory tract infections. Results may be limited by the general lack of research on this topic, the small sample sizes of the included studies, the inclusion of both recreational and elite athletes and differences in nutrient composition of different vegetarian diets.
Grade of Evidence C
 
Remarks
Vegetarian diets are thought to enhance athletic performance by improving cardiovascular function and by reducing oxidative stress, inflammation and immune responses.
 
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10. High Protein Plant-based Diets to Increase Muscle Mass
Recommendation
High protein plant-based diets (>1.6 g/kg/day) may support increases to muscle mass and strength in healthy, physically active young adults participating in strength training as well as omnivorous diets. Evidence for other populations is lacking.

Evidence Summary
Results from three separate trials lasting between four and 12 weeks involving healthy, physically active young adults (n=16 to 38 participants/study) suggest that high protein plant-based diets (i.e. a minimum of 1.6 g/kg/day) increased measurements of muscle mass and strength (e.g. lean mass, muscle strength, skeletal muscle size) as well as omnivorous diets. Results may be limited by small sample sizes, short durations and that not all the plant-based diets excluded all animal proteins. Additional considerations are the use of protein supplements and that findings may not be generalizable beyond healthy, physically active young adults.
Grade of Evidence C
 
Remarks
High protein diets were defined as a least 1.6 g/kg/day in one study and at least 1.8 g/kg/day in another study, and while no definition of high protein was given in the third study, all diets in this study contained at least 0.8 to 1.2 g/kg/day, which is the minimum amount for general fitness recommended by the International Society of Sports Nutrition. Protein supplements (e.g. soy, mycoprotein, milk proteins) were used in two of the studies to support participants to reach the recommended amounts.
 
Mycoprotein is protein that is derived from fungus.

11. Iron Deficiency in Vegetarian Athletes 
Recommendation
Vegetarian and vegan athletes may be at higher risk of iron deficiency than non-vegetarian athletes due to the lower bioavailability of non-heme iron compared to heme iron. Vegetarian athletes who menstruate may not be able to meet their iron needs through diet alone.

Evidence Summary
A 2023 narrative review discussing the effects of a vegan diet on the nutritional status of athletes indicated that iron deficiency is common in athletes generally, but the authors did not compare the rates of iron deficiency in vegetarian and non-vegetarian athletes. Vegetarian and vegan athletes may be at higher risk of iron deficiency due to inadequate iron intake or the presence of anti-nutrients (e.g. phytates, calcium) in plant foods that reduce the bioavailability of non-heme iron. Vegetarian athletes who menstruate may not be able to meet their iron needs through diet alone. Findings may be limited by the low methodological quality of this study.
Grade of Evidence C
 
Remarks
Iron deficiency in athletes is likely due to a combination of factors including iron lost through sweating, hemolysis, gastrointestinal bleeding, menstrual blood loss and increased hepcidin concentrations that decrease iron absorption and availability.
 
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Target Group: All Adults, All children(0-12 yr.), Youth(13-17 yr.)
Knowledge Pathways: Sports Nutrition
 Last Updated: 2024-04-26