In particular and as it relates to exercise performance, the need for optimal carbohydrates before, during and after intense and high-volume bouts of training and competition is evident [ 41 ]. Excellent reviews [ 42 , 43 ] and original investigations [ 44 , 45 , 46 , 47 , 48 , 49 ] continue to highlight the known dependence on carbohydrates that exists for athletes competing to win various endurance and team sport activities.

A complete discussion of the needs of carbohydrates and strategies to deliver optimal carbohydrate and replenish lost muscle and liver glycogen extend beyond the scope of this paper, but the reader is referred to several informative reviews on the topic [ 23 , 41 , 50 , 51 , 52 , 53 ].

As such, individuals engaged in a general fitness program and are not necessarily training to meet any type of performance goal can typically meet daily carbohydrate needs by consuming a normal diet i. However, athletes involved in moderate and high-volume training need greater amounts of carbohydrate and protein discussed later in their diet to meet macronutrient needs [ 50 ].

In terms of carbohydrate needs, athletes involved in moderate amounts of intense training e. Research has also shown that athletes involved in high volume intense training e. Preferably, the majority of dietary carbohydrate should come from whole grains, vegetables, fruits, etc.

while foods that empty quickly from the stomach such as refined sugars, starches and engineered sports nutrition products should be reserved for situations in which glycogen resynthesis needs to occur at accelerated rates [ 53 ]. When considering the carbohydrate needs throughout an exercise session, several key factors should be considered.

Previous research has indicated athletes undergoing prolonged bouts 2—3 h of exercise training can oxidize carbohydrates at a rate of 1—1.

Several reviews advocate the ingestion of 0. It is now well established that different types of carbohydrates can be oxidized at different rates in skeletal muscle due to the involvement of different transporter proteins that result in carbohydrate uptake [ 55 , 56 , 57 , 58 , 59 ].

Interestingly, combinations of glucose and sucrose or maltodextrin and fructose have been reported to promote greater exogenous rates of carbohydrate oxidation when compared to situations when single sources of carbohydrate are ingested [ 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ].

These studies generally indicate a ratio of 1—1. In addition to oxidation rates and carbohydrate types, the fasting status and duration of the exercise bout also function as key variables for athletes and coaches to consider. When considering duration, associated reviews have documented that bouts of moderate to intense exercise need to reach exercise durations that extend well into 90th minute of exercise before carbohydrate is shown to consistently yield an ergogenic outcome [ 41 , 68 , 69 ].

Of interest, however, not all studies indicate that shorter 60—75 min bouts of higher intensity work may benefit from carbohydrate delivery. Currently the mechanisms surrounding these findings are, respectively, thought to be replacement of depleted carbohydrate stores during longer duration of moderate intensity while benefits seen during shorter, more intense exercise bouts are thought to operate in a central fashion.

Moreover, these reviews have also pointed to the impact of fasting status on documentation of ergogenic outcomes [ 41 , 68 , 69 ]. In this respect, when studies require study participants to commence exercise in a fasted state, ergogenic outcomes are more consistently reported, yet other authors have questioned the ecological validity of this approach for competing athletes [ 43 ].

As it stands, the need for optimal carbohydrates in the diet for those athletes seeking maximal physical performance is unquestioned.

Daily consumption of appropriate amounts of carbohydrate is the first and most important step for any competing athlete. As durations extend into 2 h, the need to deliver carbohydrate goes up, particularly when commencing exercise in a state of fasting or incomplete recovery.

Once exercise ceases, several dietary strategies can be considered to maximally replace lost muscle and liver glycogen, particularly if a limited window of recovery exists.

In these situations, the first priority should lie with achieving aggressive intakes of carbohydrate while strategies such as ingesting protein with lower carbohydrate amounts, carbohydrate and caffeine co-ingestion or certain forms of carbohydrate may also help to facilitate rapid assimilation of lost glycogen.

Initially, it was recommended that athletes do not need to ingest more than the RDA for protein i. However, research spanning the past 30 years has indicated that athletes engaged in intense training may benefit from ingesting about two times the RDA of protein in their diet 1.

If an insufficient amount of protein is consumed, an athlete will develop and maintain a negative nitrogen balance, indicating protein catabolism and slow recovery.

Over time, this may lead to muscle wasting, injuries, illness, and training intolerance [ 76 , 77 , 81 ]. For people involved in a general fitness program or simply interested in optimizing their health, recent research suggests protein needs may also be above the RDA.

Phillips and colleagues [ 76 ], Witard et al. In this respect, Morton and investigators [ 83 ] performed a meta-review and meta-regression involving 49 studies and participants and concluded that a daily protein intake of 1.

In addition and in comparison to the RDA, non-exercising, older individuals 53—71 years may also benefit from a higher daily protein intake e. Recent reports suggest that older muscle may be slower to respond and less sensitive to protein ingestion, typically requiring 40 g doses to robustly stimulate muscle protein synthesis [ 84 , 85 , 86 ].

Studies in younger individuals, however, have indicated that in the absence of exercise, a 20 g dose can maximize muscle protein synthesis [ 87 , 88 ] and if consumed after a multiple set workout consisting of several exercises that target large muscle groups a 40 g dose might be needed [ 89 ].

Consequently, it is recommended that athletes involved in moderate amounts of intense training consume 1. This protein need would be equivalent to ingesting 3—15 three-ounce servings of chicken or fish per day for a 50— kg athlete [ 78 ]. Although smaller athletes typically can ingest this amount of protein, on a daily basis, in their normal diet, larger athletes often have difficulty consuming this much dietary protein.

Additionally, a number of athletic populations are known to be susceptible to protein malnutrition e. and consequently, additional counseling and education may be needed to help these athletes meet their daily protein needs. Overall, it goes without saying that care should be taken to ensure that athletes consume a sufficient amount of quality protein in their diet to maintain nitrogen balance.

Proteins differ based on their source, amino acid profile, and the methods of processing or isolating the protein undergoes [ 11 ]. These differences influence the availability of amino acids and peptides, which may possess biological activity e. For example, different types of proteins e. Therefore, care should be taken not only to make sure the athlete consumes enough protein in their diet but also that the protein is high quality.

The best dietary sources of low fat, high quality protein are light skinless chicken, fish, egg whites, very lean cuts of beef and skim milk casein and whey while protein supplements routinely contain whey, casein, milk and egg protein. In what is still an emerging area of research, various plant sources of protein have been examined for their ability to stimulate increases in muscle protein synthesis [ 77 , 97 ] and promote exercise training adaptations [ 98 ].

While amino acid absorption from plant proteins is generally slower, leucine from rice protein has been found to be absorbed even faster than from whey [ 99 ], while digestive enzymes [ ], probiotics [ ] and HMB [ ] can be used to overcome differences in protein quality.

Preliminary findings suggest that rice [ 98 ] and pea protein [ ] may be able to stimulate similar changes in fat-free mass and strength as whey protein, although the reader should understand that many other factors dose provided, training status of participants, duration of training and supplementation, etc.

will ultimately impact these outcomes and consequently more research is needed. While many reasons and scenarios exist for why an athlete may choose to supplement their diet with protein powders or other forms of protein supplements, this practice is not considered to be an absolute requirement for increased performance and adaptations.

Due to nutritional, societal, emotional and psychological reasons, it is preferable for the majority of daily protein consumed by athletes to occur as part of a food or meal. However, we recognize and embrace the reality that situations commonly arise where efficiently delivering a high-quality source of protein takes precedence.

Jager and colleagues [ 11 ] published an updated position statement of the International Society of Sports Nutrition that is summarized by the following points:. An acute exercise stimulus, particularly resistance exercise and protein ingestion both stimulate muscle protein synthesis MPS and are synergistic when protein consumption occurs before or after resistance exercise.

For building and maintaining muscle mass, an overall daily protein intake of 1. Higher protein intakes 2. Optimal doses for athletes to maximize MPS are mixed and are dependent upon age and recent resistance exercise stimuli.

General recommendations are 0. The optimal time period during which to ingest protein is likely a matter of individual tolerance; however, the anabolic effect of exercise is long-lasting at least 24 h , but likely diminishes with increasing time post-exercise.

Rapidly digested proteins that contain high proportions of EAAs and adequate leucine, are most effective in stimulating MPS. Different types and quality of protein can affect amino acid bioavailability following protein supplementation; complete protein sources deliver all required EAAs.

The dietary recommendations of fat intake for athletes are similar to or slightly greater than dietary recommendations made to non-athletes to promote health. Maintenance of energy balance, replenishment of intramuscular triacylglycerol stores and adequate consumption of essential fatty acids are important for athletes, and all serve as reasons for an increased intake of dietary fat [ ].

For example, higher-fat diets appear to maintain circulating testosterone concentrations better than low-fat diets [ , , ]. Additionally, higher fat intakes may provide valuable translational evidence to the documented testosterone suppression which can occur during volume-type overtraining [ ].

In situations where an athlete may be interested in reducing their body fat, dietary fat intakes ranging from 0. This recommendation stems largely from available evidence in weight loss studies involving non-athletic individuals that people who are most successful in losing weight and maintaining the weight loss are those who ingest reduced amounts of fat in their diet [ , ] although this is not always the case [ ].

Strategies to help athletes manage dietary fat intake include teaching them which foods contain various types of fat so that they can make better food choices and how to count fat grams [ 2 , 33 ]. For years, high-fat diets have been used by athletes with the majority of evidence showing no ergogenic benefit and consistent gastrointestinal challenges [ ].

In recent years, significant debate has swirled regarding the impact of increasing dietary fat. While intramuscular adaptations result that may theoretically impact performance [ , ], no consistent, favorable impact on performance has been documented [ , ].

A variant of high-fat diets, ketogenic diets, have increased in popularity. This diet prescription leads to a greater reliance on ketones as a fuel source. Currently, limited and mixed evidence remains regarding the overall efficacy of a ketogenic diet for athletes.

In favor, Cox et al. Additionally, Jabekk and colleagues [ ] reported decreases in body fat with no change in lean mass in overweight women who resistance trained for 10 weeks and followed a ketogenic diet. In light of the available evidence being limited and mixed, more human research needs to be completed before appropriate recommendations can be made towards the use of high fat diets for athletic performance.

In addition to the general nutritional guidelines described above, research has also demonstrated that timing and composition of meals consumed may play a role in optimizing performance, training adaptations, and preventing overtraining [ 2 , 25 , 40 ].

In this regard, it takes about 4 h for carbohydrate to be digested and assimilated into muscle and liver tissues as glycogen. Consequently, pre-exercise meals should be consumed about four to 6 h before exercise [ 40 ]. This means that if an athlete trains in the afternoon, breakfast can be viewed to have great importance to top off muscle and liver glycogen levels.

Research has also indicated that ingesting a light carbohydrate and protein snack 30 to 60 min prior to exercise e. This also serves to increase availability of amino acids, decrease exercise-induced catabolism of protein, and minimize muscle damage [ , , ].

Additionally, athletes who are going through periods of energy restriction to meet weight or aesthetic demands of sports should understand that protein intake, quality and timing as well as combination with carbohydrate is particularly important to maintain lean body mass, training effects, and performance [ 25 ].

Notably, this strategy becomes even more important if the athlete is under-fueled prior to the exercise task or is fasted vs. unfasted at the start of exercise [ 68 , 69 , ]. Following intense exercise, athletes should consume carbohydrate and protein e.

This eating strategy has been shown to supersaturate carbohydrate stores prior to competition and improve endurance exercise capacity [ 2 , 40 ]. Thus, the type of meal, amount of carbohydrate consumed, and timing of eating are important factors to maximize glycogen storage and in maintaining carbohydrate availability during training while also potentially decreasing the incidence of overtraining.

The ISSN has adopted a position stand on nutrient timing in [ ] that has been subsequently revised [ 13 ] and can be summarized with the following points:.

The importance of this strategy is increased when poor feeding or recovery strategies were employed prior to exercise commencement. Consequently, when carbohydrate delivery is inadequate, adding protein may help increase performance, mitigate muscle damage, promote euglycemia, and facilitate glycogen re-synthesis.

Ingesting efficacious doses 10—12 g of essential amino acids EAAs either in free form or as a protein bolus in 20—40 g doses 0. However, the size 0. Post-exercise ingestion immediately-post to 2 h post of high-quality protein sources stimulates robust increases in MPS.

Similar increases in MPS have been found when high-quality proteins are ingested immediately before exercise. Vitamins are essential organic compounds that serve to regulate metabolic and neurological processes, energy synthesis, and prevent destruction of cells.

Water-soluble vitamins consist of the entire complex of B-vitamins and vitamin C. Since these vitamins are water-soluble, excessive intake of these vitamins are eliminated in urine, with few exceptions e.

vitamin B6, which can cause peripheral nerve damage when consumed in excessive amounts. Table 1 describes the RDA, proposed ergogenic benefit, and summary of research findings for fat and water-soluble vitamins.

Research has demonstrated that specific vitamins possess various health benefits e. Alternatively, if an athlete is deficient in a vitamin, supplementation or diet modifications to improve vitamin status can consistently improve health and performance [ ].

For example, Paschalis and colleagues [ ] supplemented individuals who were low in vitamin C for 30 days and reported these individuals had significantly lower VO 2 Max levels than a group of males who were high in vitamin C.

Further, after 30 days of supplementation, VO 2 Max significantly improved in the low vitamin C cohort as did baseline levels of oxidative stress of oxidative stress. Furthermore, while optimal levels of vitamin D have been linked to improved muscle health [ ] and strength [ ] in general populations, research studies conducted in athletes generally fail to report on the ergogenic impact of vitamin D in athletes [ , ].

However, equivocal evidence from Wyon et al. The remaining vitamins reviewed appear to have little ergogenic value for athletes who consume a normal, nutrient dense diet. Finally, athletes may desire to consume a vitamin or mineral for various health non-performance related reasons including niacin to elevate high density lipoprotein HDL cholesterol levels and decrease risk of heart disease niacin , vitamin E for its antioxidant potential, vitamin D for its ability to preserve musculoskeletal function, or vitamin C to promote and maintain a healthy immune system.

Minerals are essential inorganic elements necessary for a host of metabolic processes. Minerals serve as structure for tissue, important components of enzymes and hormones, and regulators of metabolic and neural control.

Notably, acute changes in sodium, potassium and magnesium throughout a continued bout of moderate to high intensity exercise are considerable. In these situations, athletes must work to ingest foods and fluids to replace these losses, while physiological adaptations to sweat composition and fluid retention will also occur to promote a necessary balance.

Like vitamins, when mineral status is inadequate, exercise capacity may be reduced and when minerals are supplemented in deficient athletes, exercise capacity has been shown to improve [ ]. However, scientific reports consistently fail to document a performance improvement due to mineral supplementation when vitamin and mineral status is adequate [ , , ].

Table 2 describes minerals that have been purported to affect exercise capacity in athletes. For example, calcium supplementation in athletes susceptible to premature osteoporosis may help maintain bone mass [ ]. Increasing dietary availability of salt sodium chloride during the initial days of exercise training in the heat helps to maintain fluid balance and prevent dehydration.

Finally, zinc supplementation during training can support changes in immune status in response to exercise training. However, there is little evidence that boron, chromium, magnesium, or vanadium affect exercise capacity or training adaptations in healthy individuals eating a normal diet.

The most important nutritional ergogenic aid for athletes is water and limiting dehydration during exercise is one of the most effective ways to maintain exercise capacity. Before starting exercise, it is highly recommended that individuals are adequately hydrated [ ]. When one considers that average sweat rates are reported to be 0.

For this reason, it is critical that athletes adopt a mind set to prevent dehydration first by promoting optimal levels of pre-exercise hydration. Throughout the day and without any consideration of when exercise is occurring, a key goal is for an athlete to drink enough fluids to maintain their body weight.

Next, athletes can promote optimal pre-exercise hydration by ingesting mL of water or sports drinks the night before a competition, another mL upon waking and then another — mL of cool water or sports drink 20—30 min before the onset of exercise.

Consequently, to maintain fluid balance and prevent dehydration, athletes need to plan on ingesting 0. This requires frequent every 5—15 min ingestion of 12—16 fluid ounces of cold water or a sports drink during exercise [ , , , , ].

Athletes should not depend on thirst to prompt them to drink because people do not typically get thirsty until they have lost a significant amount of fluid through sweat. Additionally, athletes should weigh themselves prior to and following exercise training to monitor changes in fluid balance and then can work to replace their lost fluid [ , , , , ].

During and after exercise, athletes should consume three cups of water for every pound lost during exercise to promote adequate rehydration [ ]. A primary goal soon after exercise should be to completely replace lost fluid and electrolytes during a training session or competition.

Additionally, sodium intake in the form of glucose-electrolyte solutions vs. only drinking water and making food choices and modifications added salt to foods should be considered during the rehydration process to further promote euhydration [ ].

Finally, inappropriate and excessive weight loss techniques e. are considered dangerous and should be prohibited. Sport nutritionists, dietitians, and athletic trainers can play an important role in educating athletes and coaches about proper hydration methods and supervising fluid intake during training and competition.

Educating athletes and coaches about nutrition and how to structure their diet to optimize performance and recovery are key areas of involvement for sport dietitians and nutritionists. Currently, use of dietary supplements by athletes and athletic populations is widespread while their overall need and efficacy of certain ingredients remain up for debate.

Dietary supplements can play a meaningful role in helping athletes consume the proper amount of calories, macro- and micronutrients. Dietary supplements are not intended to replace a healthy diet.

Supplementation with these nutrients in clinically validated amounts and at opportune times can help augment the normal diet to help optimize performance or support adaptations towards a training outcome. Sport dietitians and nutritionists must be aware of the current data regarding nutrition, exercise, and performance and be honest about educating their clients about results of various studies whether pro or con.

Currently, misleading information is available to the public and this position stand is intended to objectively rate many of the available ingredients. Additionally, athletes, coaches and trainers need to also heed the recommendations of scientists when recommendations are made according to the available literature and what will hopefully be free of bias.

We recognize that some ingredients may exhibit little potential to stimulate training adaptations or operate in an ergogenic fashion, but may favorably impact muscle recovery or exhibit health benefits that may be helpful for some populations.

These outcomes are not the primary focus of this review and consequently, will not be discussed with the same level of detail. Consequently, meal replacements should be used in place of a meal during unique situations and are not intended to replace all meals.

Care should also be taken to make sure they do not contain any banned or prohibited nutrients. The following section provides an analysis of the scientific literature regarding nutritional supplements purported to promote skeletal muscle accretion in conjunction with the completion of a well-designed exercise-training program.

An overview of each supplement and a general interpretation of how they should be categorized is provided throughout the text. Table 3 summarizes how every supplement discussed in this article is categorized.

However, within each category all supplements are ordered alphabetically. For example, increases in body mass and lean mass are desired adaptations for many American football or rugby players and may improve performance in these activities.

In contrast, decreases in body mass or fat mass may promote increases in performance such as cyclists and gymnasts whereby athletes such as wrestlers, weightlifters and boxers may need to rapidly reduce weight while maintaining muscle mass, strength and power.

HMB is a metabolite of the amino acid leucine. It is well-documented that supplementing with 1. The currently established minimal effective dose of HMB is 1.

To optimize HMB retention, its recommend to split the daily dose of 3 g into three equal doses of 1 g each with breakfast, lunch or pre-exercise, bedtime [ ].

From a safety perspective, dosages of 1. The effects of HMB supplementation in trained athletes are less clear with selected studies reporting non-significant gains in muscle mass [ , , ]. In this respect, it has been suggested by Wilson and colleagues [ 15 ] that program design periodized resistance training models and duration of supplementation minimum of 6 weeks likely operate as key factors.

Before and after each supplementation period, body composition and performance parameters were assessed. When HMB was provided, fat mass was significantly reduced while changes in lean mass were not significant between groups.

The same research group published data of 58 highly trained males athletes who supplemented with either 3 g of calcium-HMB or placebo for 12 weeks in a randomized, double-blind, crossover fashion [ ]. In this report, fat mass was found to be significantly reduced while fat-free mass was significantly increased.

Finally, Durkalec-Michalski and investigators [ ] supplemented 42 highly-trained combat sport athletes for 12 weeks with either a placebo or 3 g of calcium-HMB in a randomized, double-blind, crossover fashion.

In conclusion, a growing body of literature continues to offer support that HMB supplementation at dosages of 1. In our view, the most effective nutritional supplement available to athletes to increase high intensity exercise capacity and muscle mass during training is creatine monohydrate.

Body mass increases are typically one to two kilograms greater than controls during 4—12 weeks of training [ ]. The gains in muscle mass appear to be a result of an improved ability to perform high intensity exercise enabling an athlete to train harder and thereby promote greater training adaptations and muscle hypertrophy [ , , , ].

The only clinically significant side effect occasionally reported from creatine monohydrate supplementation has been the potential for weight gain [ , , , ].

The ISSN position stand on creatine monohydrate [ 10 ] summarizes their findings as this:. Creatine monohydrate is the most effective ergogenic nutritional supplement currently available to athletes in terms of increasing high-intensity exercise capacity and lean body mass during training.

Creatine monohydrate supplementation is not only safe, but has been reported to have a number of therapeutic benefits in healthy and diseased populations ranging from infants to the elderly.

If proper precautions and supervision are provided, creatine monohydrate supplementation in children and adolescent athletes is acceptable and may provide a nutritional alternative with a favorable safety profile to potentially dangerous anabolic androgenic drugs.

At present, creatine monohydrate is the most extensively studied and clinically effective form of creatine for use in nutritional supplements in terms of muscle uptake and ability to increase high-intensity exercise capacity.

The addition of carbohydrate or carbohydrate and protein to a creatine supplement appears to increase muscular uptake of creatine, although the effect on performance measures may not be greater than using creatine monohydrate alone.

Initially, ingesting smaller amounts of creatine monohydrate e. Clinical populations have been supplemented with high levels of creatine monohydrate 0. Further research is warranted to examine the potential medical benefits of creatine monohydrate and precursors like guanidinoacetic acid on sport, health and medicine.

Research examining the impact of the essential amino acids on stimulating muscle protein synthesis is an extremely popular area. Theoretically, this may enhance increases in fat-free mass, but to date limited evidence exists to demonstrate that supplementation with non-intact sources of EAAs e.

Moreover, other research has indicated that changes in muscle protein synthesis may not correlate with phenotypic adaptations to exercise training [ ]. An abundance of evidence is available, however, to indicate that ingestion of high-quality protein sources can heighten adaptations to resistance training [ ].

While various methods of protein quality assessment exist, most of these approaches center upon the amount of EAAs that are found within the protein source, and in nearly all situations, the highest quality protein sources are those containing the highest amounts of EAAs. To this point, a number of published studies are available that state the EAAs operate as a prerequisite to stimulate peak rates of muscle protein synthesis [ , , , ].

To better understand the impact of ingesting free-form amino acids versus an intact protein source, Katsanos et al. Protein accrual was greater when the amino acid dose was provided in an intact source. While the EAAs are comprised of nine separate amino acids, some individual EAAs have received considerable attention for their potential role in impacting protein translation and muscle protein synthesis.

In this respect, the branched-chain amino acids have been highlighted for their predominant role in stimulating muscle protein synthesis [ , ]. Interestingly, Moberg and investigators [ ] had trained volunteers complete a standardized bout of resistance training in conjunction with ingestion of placebo, leucine, BCAA or EAA while measuring changes in post-exercise activation of p70s6k.

They concluded that EAA ingestion led to a nine-fold greater increase in p70s6k activation and that these results were primarily attributable to the BCAAs. Finally, a study by Jackman et al. While significant, this magnitude of change was notably less than the post-exercise MPS responses seen when doses of whey protein that delivered similar amounts of the BCAAs were consumed [ 88 , ].

These outcomes led the authors to conclude that the full complement of EAAs was advised to maximally stimulate increases in MPS.

Of all the interest captured by the BCAAs, leucine is accepted to be the primary driver of acute changes in protein translation. In this respect, Dreyer et al. In this respect, Jager et al.

A growing body of literature is available that suggests higher amounts of protein are needed by exercising individuals to optimize exercise training adaptations [ 11 , 83 , , ]. Collectively, these sources indicate that people undergoing intense training with the primary intention to promote accretion of fat-free mass should consume between 1.

Tang and colleagues [ 95 ] conducted a classic study that examined the ability of three different sources of protein hydrolyzed whey isolate, micellar casein and soy isolate to stimulate acute changes in muscle protein synthesis both at rest and after a single bout of resistance exercise.

These authors concluded that all three protein sources significantly increased muscle protein synthesis rates both at rest and in response to resistance exercise. When this response is extrapolated over the course of several weeks, multiple studies have reported on the ability of different forms of protein to significantly increase fat-free mass while resistance training [ 70 , , , , , , ].

Cermak et al. Data from 22 separate published studies that included research participants were included in the analysis. These authors concluded that protein supplementation demonstrated a positive effect of fat-free mass and lower-body strength in both younger and older participants.

Similarly, Morton and investigators [ 83 ] published results from a meta-analysis that also included a meta-regression approach involving data from 49 studies and participants. They concluded that the ability of protein to positively impact fat-free mass accretion increases up to approximately 1.

Although more research is necessary in this area, evidence clearly indicates that protein needs of individuals engaged in intense training are elevated and consequently those athletes who achieve higher intakes of protein while training promote greater changes in fat-free mass.

Beyond the impact of protein to foster greater training-induced adaptations such as increases in strength and muscle mass, several studies have examined the ability of different types of protein to stimulate changes in fat-free mass [ , , , , ] while several studies and reviews have critically explored the role protein may play in achieving weight loss in athletes [ , ] as well as during periods of caloric restriction [ , ].

It is the position stand of ISSN that exercising individuals need approximately 1. ATP is the primary intracellular energy source and in addition, has extensive extracellular functions including the increase in skeletal muscle calcium permeability and vasodilation.

While intravenous administration of ATP is bioavailable [ ], several studies have shown that oral ATP is not systematically bioavailable [ ]. However, chronic supplementation with ATP increases the capacity to synthesize ATP within the erythrocytes without increasing resting concentrations in the plasma, thereby minimizing exercise-induced drops in ATP levels [ ].

Oral ATP supplementation has demonstrated initial ergogenic properties, after a single dose, improving total weight lifted and total number of repetitions [ ]. ATP may increase blood flow to the exercising muscle [ ] and may reduce fatigue and increase peak power output during later bouts of repeated bouts exercise [ ].

ATP may also support greater recovery and lean mass maintenance under high volume training [ ], however, this has only been reported in one previous study. In addition, ATP supplementation in clinical populations has been shown to improve strength, reduce pain after knee surgery, and reduce the length of the hospital stay [ ].

However, given the limited number of human studies of ATP on increasing exercise-induced gains in muscle mass, more chronic human training studies are warranted. Leucine, in particular, is recognized as a keystone of sorts that when provided in the correct amounts 3—6 g activates the mTORC1 complex resulting in favorable initiation of translation [ ].

To highlight this impact for leucine, varying doses of whey protein and leucine levels were provided to exercising men at rest and in response to an acute bout of lower-body resistance exercise to examine the muscle protein synthetic response.

Interestingly, when a low dose of whey protein 6. While the g dose of whey protein did favorably sustain the increases in muscle protein synthesis, the added leucine highlights an important role for leucine in stimulating muscle protein synthesis in response to resistance exercise [ ].

For these reasons, it has been speculated that the leucine content of whey protein and other high-quality protein sources have been suggested to be primary reasons for their ability to stimulate favorable adaptations to resistance training [ , ].

Theoretically, BCAA supplementation during intense training may help minimize protein degradation and thereby lead to greater gains in or limit losses of fat-free mass, but only limited evidence exists to support this hypothesis.

Bigard and associates [ ] reported that BCAA supplementation appeared to minimize loss of muscle mass in subjects training at altitude for 6 weeks.

Alternatively, Spillane and colleagues [ ] reported that 8 weeks of resistance training while supplementing with either 9 g of BCAAs or placebo did not impact body composition or muscle performance. Most recently, Jackman et al. As mixed outcomes cloud the ability to make clear determinations, studies strongly suggest a mechanistic role for BCAAs and in particular leucine, yet translational data fails to consistently support the need for BCAA supplementation.

Alternatively, multiple studies do support BCAAs ability to mitigate recovery from damaging exercise while their ability to favorably impact resistance training adaptations needs further research.

This will be discussed in a later section. Phosphatidic acid PA is a diacyl-glycerophospholipid that is enriched in eukaryotic cell membranes and it can act as a signalling lipid [ ].

Interestingly, PA has been repeatedly shown to activate the mammalian target of rapamycin mTOR signalling in muscle; an effect which ultimately leads to increases in muscle protein synthesis. For instance, Fang et al.

Hornberger et al. Hoffman et al. Joy et al. A third study confirmed the beneficial effects of PA on exercise-induced gains in lean body mass [ ]. The currently established dose of PA is mg per day and another study investigating lower doses, and mg per day, failed to show significant benefits on lean body mass [ ].

Hence, preliminary human research suggests that PA supplementation can increase anabolic signalling in skeletal muscle and enhance gains in muscle mass with resistance training. Given that PA supplementation studies are in their infancy relative to other muscle-building supplements e.

Agmatine, the decarboxylation product of the amino acid L-arginine, has shown different biological effects in different in vitro and animal models [ ] indicating potential benefits in an athletic population.

Agmatine is thought to improve insulin release and glucose uptake, assist in the secretion of luteinizing hormone, influence the nitric oxide signalling pathway, offer protection from oxidative stress, and is potentially involved in neurotransmission [ ].

It is mostly found in fermented foods [ ], with higher levels found in alcoholic beverages. Currently, nearly all research involving agmatine is commonly from animal research models and no human studies have been conducted to examine its impact on blood flow or impacting resistance training adaptations such as strength and body composition.

There does not appear to be any scientific evidence that Agmatine supports increases in lean body mass or muscular performance. α-ketoglutarate α-KG is an intermediate in the Krebs cycle that is involved in aerobic energy metabolism and may function to stimulate nitric oxide production.

There is some clinical evidence that α-KG may serve as an anticatabolic nutrient after surgery [ , ]. However, it is unclear whether α-KG supplementation during training may affect training adaptations. Very little research has been conducted on just alpha-ketoglutarate in humans to examine exercise outcomes.

For example, Little and colleagues [ ] supplemented with creatine, a combination of creatine, α-KG, taurine, BCAA and medium-chain triglycerides, or a placebo. The combination of nutrients increased the maximal number of bench press repetitions completed and Wingate peak power while no changes were reported in the placebo group.

Campbell and investigators [ ] supplemented 35 healthy trained men with 2 g of arginine and 2 g of α-KG or placebo in a double-blind manner while resistance training for 8 weeks. Finally, Willoughby and colleagues [ ] examined the results of arginine α-KG supplementation in relation to increasing nitric oxide production vasodilation during resistance exercise , hemodynamics, brachial artery flow, circulating levels of l-arginine, and asymmetric dimethyl arginine in active males.

This study found that although plasma L-arginine increased, there was no significant impact of supplementation on nitric oxide production after a bout of resistance exercise.

Due to the lack of research on α-KG examining its impact on exercise training adaptations, its use cannot be recommended at this time.

Arginine is commonly classified as a conditionally essential amino acid and has been linked to nitric oxide production and increases in blood flow that are purported to then stimulate enhanced nutrient and hormone delivery and favorably impact resistance training adaptations [ ].

To date, few studies have examined the independent impact of arginine on the ability to enhance fat-free mass increases while resistance training. Tang and colleagues [ ] used an acute model to examine the ability of an oral g dose of arginine to stimulate changes in muscle protein synthesis.

These authors reported that arginine administration failed to impact muscle protein synthesis or femoral artery blood flow.

Growth hormone levels did rise in response to arginine ingestion, which contrasts with the findings of Forbes et al. Regardless, the Tang study [ ] and others [ , ] failed to link the increase in growth hormone to changes in rates of muscle protein synthesis.

Notably, other studies have also failed to show a change in blood flow after arginine ingestion, one of its key purported benefits [ , ]. Campbell and colleagues published outcomes from an 8 week resistance training study that supplemented healthy men in a double-blind fashion with either a placebo or 2 g of arginine and 2 g of α-ketoglutarate.

No changes in fat mass or fat-free mass were reported in this study. Therefore, due to the limited data of arginine supplementation on stimulating further increases of exercise in muscle mass, its use for is not recommended at this time.

Boron is a trace mineral whose physiological role is not clearly understood. A number of proposed functions have been touted for boron: vitamin D metabolism, macromineral metabolism, immune support, increase testosterone levels and promote anabolism [ ].

Due to a lack of scientific evidence surrounding boron, no official Daily Reference Intake DRI is established. Several studies have evaluated the effects of boron supplementation during training on strength and body composition alterations.

However, these studies conducted on male bodybuilders indicate that boron supplementation 2. Further, two investigations [ , ] examined the impact of boron supplementation on bone mineral density in athletic and sedentary populations.

In both investigations, boron supplementation did not significantly influence bone mineral density. Therefore, due to the limited findings on boron supplementation, its use is not recommended, and more research is warranted to determine its physiological impact.

Chromium is a trace mineral that is actively involved in macronutrient metabolism. Clinical studies have suggested that chromium potentiates the effects of insulin, particularly in diabetic populations. Due to its close interaction with insulin, chromium supplementation has been theorized to impact anabolism and exercise training adaptations.

Initial research was promising with chromium supplementation being associated with increases in muscle and strength, particularly in women [ , , ]. Most recently, chromium supplementation was investigated for its ability to impact glycogen synthesis after high-intensity exercise and was found to exert no impact over recovery of glycogen [ ].

In summary, chromium supplementation appears to exert very little potential for its ability to stimulate or support improvements in fat-free mass.

Animal studies indicate that adding CLA to dietary feed decreases body fat, increases muscle and bone mass, has anti-cancer properties, enhances immunity, and inhibits progression of heart disease [ , , ]. Although animal studies are impressive [ , , ], human studies, at best, suggest a modest ability, independent of exercise or diet changes, of CLA to stimulate fat loss [ , , , ].

Moreover, very little research has been conducted on CLA to better understand if any scenario exists where its use may be justified. Initial work by Pinkoski et al.

Two studies are available that supplemented exercising younger [ ] and older individuals [ ] with a combination of CLA and creatine and reported significant improvements in strength and body composition, but these results are thought to be the result of creatine. Currently, it seems there is little evidence that CLA supplementation during training can affect lean tissue accretion and has limited efficacy [ ].

Also known as aspartate, aspartic acid is a non-essential amino acid. Two isomers exist within aspartic acid: L-Aspartic acid and D-Aspartic acid. D-Aspartic acid is thought to help boost athletic performance and function as a testosterone booster. It is also used to conserve muscle mass.

While limited research is available in humans examining D-aspartic, Willoughby and Leutholtz [ ] published a study to determine the impact of D-aspartic acid in relation to testosterone levels and performance in resistance-trained males. The results showed D-aspartic acid did not impact testosterone levels nor did it improve any aspect of performance.

In agreement, Melville and colleagues [ ] had participants supplement with either three or 6 g of D-aspartic acid and concluded that neither dose of D-aspartic acid stimulated any changes in testosterone and other anabolic hormones.

Later, Melville et al. Based on the currently available literature, D-aspartic acid is not recommended to improve muscle health. Ecdysterones also known as ectysterone, 20 β-Hydroxyecdysterone, turkesterone, ponasterone, ecdysone, or ecdystene are naturally derived phytoecdysteroids i.

They are typically extracted from the herbs Leuza rhaptonticum sp. They can also be found in high concentrations in the herb Suma also known as Brazilian Ginseng or Pfaffia.

Initial interest was generated for ecdysterones due to reports of research from Russia and Czechoslovakia that indicated a potential physiological benefit in insects and animals [ , , , ].

A review by Bucci on various herbals and exercise performance also mentioned suma ecdysterone [ ]. Unfortunately, the initial work was available in obscure journals with sub-standard study designs and presentation of results. In , Wilborn and coworkers [ ] completed what remains as the only study in humans to examine the impact of ecdysterones while resistance training.

Ecdysterones are not recommended for supplementation to increase training adaptations or performance. Fenugreek trigonella foenum-graecum is an Ayurvedic herb historically used to enhance masculinity and libido.

Fenugreek extract has been shown to increase testosterone levels by decreasing the activity of the aromatase enzyme metabolizing testosterone into estradiol [ , ]. Initial research by Poole et al.

After 8 weeks of supplementing and resistance training, significantly greater improvements in body fat, lower body strength, and upper body strength were observed. Wankhede and colleagues [ ] reported a significant increase in repetitions performed to failure using the bench press and a reduction in body fat when mg Fenugreek extract was consumed while following a resistance training program.

Initial research using Fenugreek extract suggests it may help improve resistance-training adaptations, but more research in different populations is needed before any further recommendations can be made.

Gamma oryzanol is a mixture of a plant sterol and ferulic acid theorized to increase anabolic hormonal responses, strength and muscle mass during training [ , ].

Although data are limited, one study reported no effect of 0. Most recently, Eslami and colleagues [ ] supplemented healthy male volunteers with either gamma oryzanol or placebo for 9 weeks while resistance training. In this study, changes in body composition were not realized, but a significant increase in strength was found in the bench press and leg curl exercise.

With limited research of mixed outcomes at this point, no conclusive recommendation can be made at this time as more research is needed to fully determine what impact, if any, gamma oryzanol supplementation may have in exercising individuals.

Glutamine is the most plentiful non-essential amino acid in the body and plays several important physiological roles [ 74 , , ]. Glutamine has been reported to increase cell volume and stimulate protein [ , , ] and glycogen synthesis [ ]. Initial research by Colker and associates [ ] reported that subjects who supplemented their diet with glutamine 5 g and BCAA 3 g enriched whey protein 40 g during resistance training promoted about a two pound greater gain in muscle mass and greater gains in strength than ingesting whey protein alone.

In contrast, Kerksick and colleagues [ ] reported no additional impact on strength, endurance, body composition and anaerobic power of combining 5 g of glutamine and 3 g of BCAAs to 40 g of whey protein in healthy men and women who resistance trained for 10 weeks. In addition, Antonio et al.

In a well-designed investigation, Candow and co-workers [ ] studied the effects of oral glutamine supplementation combined with resistance training in young adults. Thirty-one participants were randomly allocated to receive either glutamine 0.

The authors concluded glutamine supplementation during resistance training had no significant effect on muscle performance, body composition or muscle protein degradation in young healthy adults. While there may be other beneficial uses for glutamine supplementation i. gastrointestinal health and peptide uptake in stressed populations [ ] and, as mentioned previously, mitigation of soreness and recovery of lost force production [ ] , there does not appear to be any scientific evidence that it supports increases in lean body mass or muscular performance.

Growth hormone releasing peptides GHRP and other non-peptide compounds secretagogues facilitate growth hormone GH release [ , ], and can impact sleep patterns, food intake and cardiovascular functioning [ ] along with improvements in lean mass in clinical wasting states [ ].

These observations have served as the basis for development of nutritionally-based GH stimulators e. Studies looking at the purity of supplements find high rates of contamination with possibly harmful substances. Also, many products do not contain the ingredients listed on the label. Young athletes sometimes take protein supplements or nucleic acid supplements creatine to help their sports performance.

However, studies have not shown these supplements help improve sports performance in younger athletes. During puberty athletes grow and become stronger and their performance often improves very quickly. Creatine does not appear to offer any additional benefit in this age group. Most young athletes who eat a healthy, well-balanced diet do not need and would not benefit from protein supplements.

However, vegetarians may be at risk of not eating enough protein and may benefit from meal planning with a registered dietitian. See Effects of Puberty on Sports Performance: What Parents Need to Know for more information.

Caffeine is found in a variety of foods and drinks. About 3 out of 4 children consume caffeine on any given day. The FDA regulates the amount of caffeine in items sold as foods and drinks; however, it does not have control over items sold as supplements, such as energy drinks.

It is very difficult to know how much caffeine is in many of these products. Consuming too much caffeine, such as that found in powders, pills, and multiple energy drinks, can be dangerous. Although caffeine appears to improve some parts of sports performance in adults, the effects vary a lot.

The effects of caffeine are not as well studied in children. They also need to keep track of their fluid intake and how they respond to severe heat and humid conditions when exercising or competing. Athletes do not need vitamins and mineral supplements if they are eating healthy, well-balanced meals.

Low iron levels are associated with decreases in athletic performance, but high doses of iron, or of any other vitamin or mineral, have not been shown to improve sports performance in otherwise healthy athletes.

Anabolic steroids are drugs that are illegal without a doctor's prescription. Athletes sometimes use anabolic steroids to enhance muscle strength and size.

Nonathletes may use anabolic steroids because they want to look more muscular. However, there are side effects. Anabolic steroids stop growth in children and teens who are still gaining height. They may also cause long-term problems with the heart, skin, and other organs that can be severe and may be irreversible.

Note: Anti-inflammatory steroids, such as prednisone, that are used for asthma and other conditions are safe and often needed for young athletes when prescribed by a doctor.

Eat carbohydrates. Athletes should consume carbohydrate-rich foods every several hours on the day of competition. Carbohydrates are an important source of fuel during exercise. Stay hydrated. Sports performance can be enhanced when athletes get the right amount of fluid and electrolytes. Proper hydration is especially important during practices or games that last more than 60 minutes.

Here are a few guidelines to keep the body hydrated and performing at its best level. During practice and competition: Drink 4 to 8 ounces of water or sports drinks every 15 minutes throughout the practice or competition. Athletes should reload their bodies with fluids and food as soon as possible after a practice or game.

Reloading is especially important when athletes are playing in multiple games in a short time frame, such as during a basketball or soccer tournament. Eat well. A well-balanced meal with the right kinds of proteins and carbohydrates will help the muscles recover between practices and games.

Well-balanced meals are especially important if athletes are recovering from an injury and want to return to practice and competition. You may be trying to access this site from a secured browser on the server.