The same research group conducted another trial using the same doses of vitamins C and E in 32 young men and women who followed a strength-training program for 10 weeks.

Compared with placebo, the supplements did not affect muscle growth, but they significantly reduced the gain in arm strength as measured by biceps curls and blunted cellular signaling pathways linked to muscle hypertrophy [ 21 ].

After 7 days of high-intensity cycling sprints, the CoQ 10 group had, on average, a significantly smaller improvement in mean power output than the placebo group, suggesting a poorer adaptation to training.

The preponderance of research to date suggests that exercise-induced reactive oxygen species and nitric oxide are beneficial. These free radicals induce adaptive changes in muscle that lead to greater production of mitochondria and hypertrophy of myofibers [ 17 , 21 , 23 , 24 ].

However, these adaptations might not prevent improvements in VO 2 max or endurance performance [ 25 ]. Studies on the safety of vitamins C, E, and other antioxidant supplements taken during exercise show no evidence of adverse effects, aside from potentially reducing some of the benefits of exercise, but such studies have only lasted a few weeks or months.

These amounts are substantially higher than the doses that studies have typically used for exercise and athletic performance. Among the potential adverse effects of excess vitamin C are diarrhea, nausea, abdominal cramps, and other gastrointestinal disturbances.

The intake of excessive amounts of vitamin E increases the risks of hemorrhagic effects. The side effects of CoQ 10 are mild and can include fatigue, insomnia, rashes, nausea, upper abdominal pain, heartburn, sensitivity to light, irritability, dizziness, and headaches [ 28 ].

Little research supports the use as ergogenic aids of antioxidant supplements containing greater amounts than those available from a nutritionally adequate diet [ 19 , 25 ]. In fact, they can adversely affect some measures of exercise and athletic performance.

The Australian Institute of Sport, part of the government of Australia, does not recommend supplementation with vitamins C and E by athletes, except when they use these products as part of a research protocol or with proper monitoring [ 29 ]. More information on vitamin C and vitamin E is available in the Office of Dietary Supplements ODS health professional fact sheets on these nutrients.

L-arginine is an amino acid found in many protein-containing foods, especially animal products and nuts. The body also synthesizes arginine from citrulline , mainly in the kidneys.

Some experts suggest that taking arginine in supplement form enhances exercise and athletic performance in several ways [ ]. First, some arginine is converted to nitric oxide, a potent vasodilator that can increase blood flow and the delivery of oxygen and nutrients to skeletal muscle.

Second, increased vasodilation can speed up the removal of metabolic waste products related to muscle fatigue, such as lactate and ammonia, that the body produces during exercise. Third, arginine serves as a precursor for the synthesis of creatine, which helps supply muscle with energy for short-term, intense activity.

Fourth, arginine may increase the secretion of human growth hormone HGH , which in turn increases insulin-like growth factor-1 IGF-1 levels, both of which stimulate muscle growth.

The research to support supplemental arginine as a performance enhancer is limited and conflicting. Furthermore, arginine typically had no effect on nitric oxide concentration, blood flow, or exercise metabolites e.

A recent review assessed 54 clinical studies examining the effects of arginine supplementation on strength performance, endurance, muscle blood volume and flow, cardiorespiratory measures, and nitric oxide production in healthy, active adults. The authors concluded that supplemental arginine either alone or, more commonly, in combination with other ingredients, such as branched-chain amino acids [BCAAs] and lysine provided little or no enhancement of athletic performance and did not improve recovery from exhaustion [ 33 ].

Most of the studies included few participants, primarily young men age 18—25 years only four studies included women , and lasted only 4—8 weeks with none lasting 3 months or longer.

Research on the ability of supplemental arginine to raise HGH and IGF-1 serum concentrations also has had conflicting findings.

Even raised HGH secretion, however, might not translate into more blood flow into muscle or greater protein synthesis [ 31 ]. Little evidence shows supplemental arginine by itself increases muscle creatine concentrations or is superior or complementary to direct consumption of creatine [ 30 ].

The safety of taking high-dose arginine supplements for more than 3 months is not known [ 33 ]. Beets are one of the richest food sources of inorganic nitrate.

Ingested nitrate might enhance exercise and athletic performance in several ways, primarily through its conversion into nitric oxide in the body. Nitric acid is a potent vasodilator that can increase blood flow and the delivery of oxygen and nutrients to skeletal muscle.

Ingested nitrate might also enhance performance by dilating blood vessels in exercising muscle when oxygen levels decline, thereby increasing oxygen and nutrient delivery, reducing the oxygen cost of submaximal exercise, attenuating the adenosine triphosphate ATP -creatine phosphate energy system's cost associated with skeletal muscle force production, and improving oxidative phosphorylation in mitochondria [ 40 , 41 ].

Beetroot is available as a juice or juice concentrate and in powdered form; the amount of nitrate can vary considerably among products.

A growing number of clinical trials investigating beetroot juice or concentrate as an ergogenic aid have been published since Beetroot has generally improved performance and endurance to different extents compared with placebo among runners, swimmers, rowers, and cyclists in time trials and time-to-exhaustion tests, but not in all studies [ 40 , ].

Performance benefits are more likely in recreationally active nonathletes than elite athletes [ 42 , 46 ]. One study in 10 recreationally active, young male cyclists suggested a dose-response relationship [ 47 ].

Although consuming beetroot juice concentrate on each of 4 days to supply 4. However, consumption of even more beetroot juice supplying There has been little study of the effects of beetroot on anaerobic performance, such as high-volume resistance exercise with many repetitions [ 40 ].

More research is needed to clarify the potential benefits of nitrate supplementation from beetroot juice on exercise and athletic performance and to determine the best doses and dosing protocols [ 48 ]. No research has assessed longer term supplementation with beetroot-derived nitrate beyond several weeks as an ergogenic aid.

The amount of nitrate that this amount of juice provides is less than half the total nitrate consumption from a diet rich in vegetables and fruits [ 49 ].

Although not a safety concern, beetroot consumption can color the urine pink or red due to the excretion of red pigments in the beets [ 50 ].

In a position statement, the Academy of Nutrition and Dietetics AND , the Dietitians of Canada DoC , and the American College of Sports Medicine ACSM state that nitrate sources, such as beetroot juice, enhance exercise tolerance and economy and they improve endurance exercise performance in recreational athletes [ 12 ].

The Australian Institute of Sport supports the use of beetroot juice for improving sports performance in suitable athletic competitions under the direction of an expert in sports medicine, but it notes that more research might be required to understand how the supplement should be used for best results [ 29 ].

This amount of juice provides about 5—11 mmol or — mg nitrate, depending on the product [ 41 ]. Potential benefits persist for up to 24 hours after ingestion [ 40 ]. The labels on beetroot juice and concentrate usually indicate that these products are foods and not dietary supplements.

Some dietary supplements contain beetroot powder in varying amounts, but studies have not assessed whether these are viable alternatives to beetroot juice or beetroot-juice concentrate. Beta-alanine, a type of amino acid that the body does not incorporate into proteins, is the rate-limiting precursor to the synthesis of carnosine—a dipeptide of histidine and beta-alanine—in skeletal muscle.

Carnosine helps buffer changes in muscle pH from the anaerobic glycolysis that provides energy during high-intensity exercise but results in the buildup of hydrogen ions as lactic acid accumulates and dissociates to form lactate, leading to reduced force and to fatigue [ 51 ].

More carnosine in muscle leads to greater potential attenuation of exercise-induced reductions in pH, which could enhance performance of intense activities of short to moderate duration, such as rowing and swimming [ 52 ].

Beta-alanine is produced in the liver, and relatively small amounts are present in animal-based foods such as meat, poultry, and fish. Carnosine is present in animal-based foods, such as beef and pork.

However, oral consumption of carnosine is an inefficient method of increasing muscle carnosine concentrations because the dipeptide is digested into its constituent amino acids. Consumption of beta-alanine, in contrast, reliably increases the amount of carnosine in the body.

For example, in one study of young, physically active but untrained adult men who took 4. Among the low responders, the duration of the washout period when beta alanine concentrations returned to baseline values was less than half that for the high responders 6 weeks vs.

Studies have evaluated beta-alanine as a potential ergogenic aid with a variety of participants, exercise and activity protocols, and dosing regimens. Some studies suggest that beta-alanine consumption could provide small performance benefits in competitive events requiring high-intensity effort over a short period, such as rowing, swimming, and team sports e.

Other studies have found no such benefits [ 53 ]. Evidence is conflicting on whether beta-alanine consumption improves performance in endurance activities, such as cycling [ 53 , 56 ].

Experts have not reached consensus on whether beta-alanine consumption primarily benefits trained athletes or recreationally active individuals [ 53 , 57 ]. Studies provide little consistent evidence of a relationship between the dose of beta-alanine and performance effect [ 51 , 58 ].

The authors of a Department of Defense-sponsored review concluded that the limited evidence from 20 human trials did not support consumption of beta-alanine alone or in combination products by active adults to enhance athletic performance or improve recovery from exercise-related exhaustion [ 59 ].

Most of the studies in this review included young men age 18—25 years who took 1. However, performance benefits are more modest in exercise tests lasting more than 4 minutes because aerobic metabolic pathways increasingly meet energy demands. The ISSN called for more research to determine whether beta-alanine increases the strength and muscle mass that regular resistance exercise, such as weightlifting, can produce.

The authors of the most recent review of studies on beta-alanine's effects on exercise concluded that supplementation has a statistically significant and positive effect on performance including in both isolated-limb and whole-body exercises , especially in protocols lasting 30 seconds to 10 minutes [ 58 ].

However, this review also highlighted the fact that small studies of short duration using varied exercise and supplement protocols dominate this scientific literature.

The 40 placebo-controlled studies reviewed, for example, employed 65 exercise protocols and 70 exercise measures in a total of 1, participants. Furthermore, the total dose of beta-alanine that participants consumed ranged from 84 to g in studies lasting 28—90 days.

Beta-alanine supplementation appears to be safe at 1. This tingling, prickling, or burning sensation is common in the face, neck, back of the hands, and upper trunk and typically lasts 60—90 minutes but is not a painful, serious, or harmful reaction.

Use of divided doses or a sustained-release form of the supplement can attenuate paresthesia resulting from beta-alanine consumption [ 52 , 54 ]. Some research has also found that beta-alanine supplements can produce pruritus itchy skin , but the authors do not indicate the severity of this effect [ 59 ].

There are no safety data on use of the supplement for more than 1 year [ 54 , 60 ]. There is insufficient expert consensus on the value of taking beta-alanine to enhance performance in intense, short-term activities or its safety, particularly when users take it regularly for at least several months.

In a position statement, the AND, DoC, and ACSM advise that beta-alanine supplementation might improve training capacity and does enhance performance, especially of high-intensity exercise lasting 60— seconds, that acid-base disturbances resulting from increased anaerobic glycolysis would otherwise impair [ 12 ].

In its position statement, the ISSN concludes that beta-alanine supplementation improves exercise performance and attenuates neuromuscular fatigue [ 54 ]. The Australian Institute of Sport supports the use of beta-alanine for improving sports performance in suitable athletic competitions under the direction of an expert in sports medicine, but it notes that more research might be required to understand how the supplement should be used for best results [ 29 ].

It advises users to take beta-alanine supplements with meals to augment muscle carnosine levels and to use divided lower doses or take a sustained-release form if paresthesia occurs. HMB is a metabolite of the branched-chain amino acid leucine. Some experts hypothesize that skeletal muscle cells that become stressed and damaged from exercise require an exogenous source of the coenzyme for synthesis of cholesterol in their cellular membranes to restore structure and function [ 62 , 63 ].

Experts also believe that the conversion of leucine to HMB activates muscle protein synthesis and reduces protein breakdown [ 63 ]. Although studies have investigated HMB for two decades, they have used substantially different periods of supplementation 1 day to 6 weeks and daily doses 1.

Studies also used participants of different ages 19 to 50 years , training status e. It is therefore difficult to predict what, if any, benefits an exercising individual might experience from consuming HMB. There is general agreement that HMB helps speed up recovery from exercise of sufficient amount and intensity to induce skeletal muscle damage [ 63 , 65 ].

Therefore, trained athletes must exert themselves more than untrained individuals to potentially benefit from using the supplement. Some studies suggest that HMB use has additional benefits, including an ability to enhance strength, power, skeletal muscle hypertrophy, and aerobic performance in both trained and untrained people [ 63 ].

A review of safety data from nine studies found that users tolerate HMB well, and it is safe at daily intakes of 3 g for 3 to 8 weeks in younger ages 18—47 years and older ages 62—81 adults of both sexes who do or do not exercise [ 66 ].

Assessments of blood chemistry, hematology, and emotional affect found no adverse effects. Use of HMB did not alter or adversely affect any measured hematologic, hepatic, or renal-function parameters in these young men.

There is no expert consensus on the value of taking HMB for several months or longer or its safety. HMB is not on a list of evidence-based ergogenic aids issued by the AND, DoC, and the ACSM [ 12 ]. The Australian Institute of Sport does not recommend HMB supplementation by athletes, except as part of a research protocol or with proper monitoring [ 29 ].

However, the ISSN notes that HMB can enhance recovery by reducing exercise-induced skeletal muscle damage in both trained and untrained individuals [ 63 ].

HMB is available in two forms: as a mono-hydrated calcium salt HMB-Ca and a calcium-free form HMB-free acid [HMB-FA]. Those who wish to limit their calcium intake can use HMB-FA [ 63 ].

Although the latter form appears to have a faster and greater effect based on its ability to raise HMB plasma levels, more studies are needed to compare the effects of HMB-Ca with those of HMB-FA [ 63 ]. The ISSN recommends that healthy adults interested in using HMB supplements take 1—2 g HMB-Ca 60 to minutes before exercise or 1—2 g HMB-FA 30 to 60 minutes before exercise [ 63 ].

Betaine, also known as trimethylglycine, is found in foods such as beets, spinach, and whole-grain breads. The mechanisms by which betaine might enhance exercise and athletic performance are not known, but many are hypothesized.

A limited number of small studies in men have assessed betaine in supplemental form as a potential ergogenic aid. These studies, which typically examined strength- and power-based performance in bodybuilders and, occasionally, cyclists, provided conflicting results, and performance improvements tended to be modest [ ].

The several small studies of athletes described in the previous paragraph who took betaine supplements for up to several weeks found no side effects or safety concerns.

However, research has not adequately evaluated the safety of betaine. More research on betaine supplementation to enhance various types of performance, training protocols, and exercise during specific sports is needed before any recommendations for its use can be made [ 71 ].

Three essential amino acids EAAs —leucine, isoleucine, and valine—are the branched-chain amino acids BCAAs , whose name reflects their chemical structure. Unlike other EAAs, the BCAAs can be metabolized by mitochondria in skeletal muscle to provide energy during exercise [ 74 , 75 ].

The BCAAs, especially leucine, might also stimulate protein synthesis in exercised muscle [ 72 , 76 ]. The limited research on the potential ergogenic effects of the BCAAs has found little evidence to date that supplements of these amino acids improve performance in endurance-related aerobic events [ 75 ].

The BCAAs might delay feelings of fatigue or help maintain mental focus by competing with the amino acid tryptophan a precursor of the neurotransmitter serotonin that regulates mood and sleep for entry into the brain, but this effect has not been well studied [ 72 , 74 , 75 ].

Overall, however, studies to date provide inconsistent evidence of the ability of BCAAs to stimulate muscle protein synthesis beyond the capacity of sufficient dietary amounts of any high-quality protein to perform this function [ 76 ]. Furthermore, it is not clear from existing research whether consumption of protein and BCAAs before versus after a workout affects their ability to maximize muscle protein synthesis and reduce protein catabolism [ 12 , ].

Studies have not consistently shown that taking supplements of BCAAs or any of their three constituent amino acids singly enhances exercise and athletic performance, builds muscle mass, or aids in recovery from exercise. Consuming animal foods containing complete proteins—or a combination of plant-based foods with complementary proteins that together provide all EAAs—automatically increases consumption of BCAAs see section on protein.

This is also true of consuming protein powders made from complete proteins, especially whey, which has more leucine than either casein or soy [ 78 ]. Caffeine stimulates the central nervous system, muscles, and other organs such as the heart by binding to adenosine receptors on cells, thereby blocking the activity of adenosine, a neuromodulator with sedative-like properties [ 83 , 84 ].

In this way, caffeine enhances arousal, increases vigor, and reduces fatigue [ 13 , 85 , 86 ]. Caffeine also appears to reduce perceived pain and exertion [ 13 , 85 ]. During the early stages of endurance exercise, caffeine might mobilize free fatty acids as a source of energy and spare muscle glycogen [ 38 ].

Caffeine is commonly used in energy drinks and shots touted for their performance-enhancement effects [ 87 , 88 ]. It is also found in energy gels containing carbohydrates and electrolytes as well as in anhydrous caffeine-only pills.

For an individual weighing pounds 70 kg , this dose is equivalent to — mg caffeine. Taking more, however, is unlikely to improve performance further and increases the risk of side effects.

A review of the literature found that caffeine intake affected sport-specific performance e. Although 30 of the 33 trials showed positive improvements in performance, the improvements were not statistically significant in half of them [ 85 ].

In these studies, performance improvement ranged from a decrease of 0. Factors such as the timing of ingestion, caffeine intake mode or form, and habituation to caffeine could also have accounted for the varied effects on performance.

Caffeine supplementation is more likely to help with endurance-type activities such as running and activities of long duration with intermittent activity such as soccer than more anaerobic, short-term bouts of intense exercise such as sprinting or lifting weights [ 91 ].

Some evidence suggests that caffeine is more likely to improve performance in people who are not habituated to it [ 85 ]. However, other evidence shows no habituation effect of caffeine consumption on performance [ 92 ].

Other adverse effects of caffeine include insomnia, restlessness, nausea, vomiting, tachycardia, and arrhythmia [ ]. Caffeine does not induce diuresis or increase sweat loss during exercise and therefore does not reduce fluid balance in the body that would adversely affect performance [ 13 , 90 , 98 ].

For healthy adults, the U. The American Academy of Pediatrics warns that caffeine-containing energy drinks in particular have no place in the diets of children or adolescents and are not suitable for use during routine physical activity [ ].

Pure powdered caffeine is available as a dietary supplement and is very potent. Furthermore, combining caffeine with other stimulants could increase the potential for adverse effects [ 94 ]. At least two young men have died as a result of taking an unknown amount of pure powdered caffeine [ ].

Caffeine is easily and rapidly absorbed, even from the buccal membranes in the mouth, and is distributed throughout the body and brain. It reaches peak concentrations in the blood within 45 minutes of consumption and has a half-life of about 4—5 hours [ 83 ]. For a potential benefit to athletic performance, users should consume caffeine 15 to 60 minutes before exercise [ 13 , 85 ].

Consumption of caffeine with fluid during exercise of long duration might extend any performance improvements [ 85 ]. In a position statement, the AND, DoC, and ACSM state that caffeine supplementation reduces perceived fatigue and enables users to sustain exercise at the desired intensity longer [ 12 ].

The U. It adds that caffeine could reduce perceived exertion when exercise lasts longer. The Australian Institute of Sport supports the use of caffeine for improving sports performance in suitable athletic competitions under the direction of an expert in sports medicine, but it notes that more research might be required to understand how caffeine should be used for best results [ 29 ].

The World Anti-Doping Agency does not prohibit or limit caffeine use [ ]. L-citrulline is a nonessential amino acid produced in the body, mainly from glutamine, and obtained from the diet.

Watermelon is the best-known source; 1 cup diced seedless watermelon has about mg citrulline [ ]. The subsequent conversion of arginine to nitric oxide, a potent dilator of blood vessels, might be the mechanism by which citrulline could serve as an ergogenic aid.

In fact, consumption of citrulline might be a more efficient way to raise blood arginine levels than consumption of arginine because more citrulline is absorbed from the gut than arginine.

Most studies have used citrulline malate, a combination of citrulline with malic acid a constituent in many fruits that is also produced endogenously , because malate, an intermediate in the Krebs cycle, might enhance energy production [ 30 ]. The research to support supplemental citrulline as an ergogenic aid is limited and conflicting at best.

The few published studies have had heterogeneous designs and ranged in duration from 1 to 16 days. As an example, in one randomized controlled study with a crossover design, 41 healthy male weightlifters age 22—37 years consumed 8 g citrulline malate or a placebo 1 hour before completing barbell bench presses to exhaustion [ ].

Overall, participants could complete significantly more repetitions when taking the supplement and reported significantly less muscle soreness 1 and 2 days after the test. Another study that randomized 17 young healthy men and women to take citrulline without malate either 3 g before testing or 9 g over 24 hours or a placebo found that participants using the citrulline did not perform as well as those taking the placebo on an incremental treadmill test to exhaustion [ ].

Although citrulline supplementation might increase plasma levels of nitric oxide metabolites, such a response has not been directly related to any improvement in athletic performance [ 30 ].

Studies have not adequately assessed the safety of citrulline, particularly when users take it in supplemental form for months at a time. In the study of weight lifters described above, 6 of the 41 participants reported stomach discomfort after taking the supplement [ ].

The research to date does not provide strong support for taking citrulline or citrulline malate to enhance exercise or athletic performance [ 30 ]. Whether athletes in specific sports or activities might benefit from taking supplemental citrulline remains to be determined [ ].

Dietary supplements that contain citrulline provide either citrulline or citrulline malate. Citrulline malate is Sellers of some citrulline malate dietary supplements claim that they provide a higher percentage of citrulline with labels listing, for example, citrulline malate or tri-citrulline malate , but studies have not determined whether these supplements are superior to standard citrulline or citrulline malate supplements.

Creatine is one of the most thoroughly studied and widely used dietary supplements to enhance exercise and sports performance [ ]. Creatine is produced endogenously and obtained from the diet in small amounts.

It helps generate ATP and thereby supplies the muscles with energy, particularly for short-term events [ ]. A person weighing pounds has about g creatine and phosphocreatine in his or her body, almost all in the skeletal and cardiac muscles [ ].

However, it is only when users consume much greater amounts of creatine over time as a dietary supplement that it could have ergogenic effects. Metabolized creatine is converted into the waste product creatinine, which is eliminated from the body through the kidneys.

Studies in both laboratory and sports settings have found that short-term creatine supplementation for 5 to 7 days in both men and women often significantly increases strength e. In one example, a study randomized 14 healthy, resistance-trained men age 19—29 years to receive 25 g creatine monohydrate or a placebo for 6—7 days [ ].

Participants taking the supplement had significant improvements in peak power output during all five sets of jump squats and in repetitions during all five sets of bench presses on three occasions.

Compared with those taking the placebo, participants taking the creatine improved their performance in both meter sprints and six intermittent m sprints. Supplementation with creatine over weeks or months helps training adaptations to structured, increased workloads over time.

Individuals have varied responses to creatine supplementation, based on factors such as diet and the relative percentages of various muscle fiber types [ , ]. Vegetarians, for example, with their lower muscle creatine content, might have greater responses to supplementation than meat eaters.

Overall, creatine enhances performance during repeated short bursts of high-intensity, intermittent activity, such as sprinting and weight lifting, where energy for this predominantly anaerobic exercise comes mainly from the ATP-creatine phosphate energy system [ 38 , ]. Creatine supplementation seems to be of little value for endurance sports, such as distance running or swimming, that do not depend on the short-term ATP-creatine phosphate system to provide short-term energy, and it leads to weight gain that might impede performance in such sports [ , ].

Furthermore, in predominantly aerobic exercise lasting more than seconds, the body relies on oxidative phosphorylation as the primary energy source, a metabolic pathway that does not require creatine [ ]. Studies have found no consistent set of side effects from creatine use, except that it often leads to weight gain, because it increases water retention and possibly stimulates muscle protein synthesis [ , ].

Several studies have found that supplemental creatine monohydrate, when used for a strength-training program, can lead to a 1—2 kg increase in total body weight in a month [ 73 ]. Creatine is considered safe for short-term use by healthy adults [ 12 , , , ]. In addition, evidence shows that use of the product for several years is safe [ , ].

Anecdotal reactions to creatine use include nausea, diarrhea and related gastrointestinal distress, muscle cramps, and heat intolerance. Creatine supplementation may reduce the range of motion of various parts of the body such as the shoulders, ankles, and lower legs and lead to muscle stiffness and resistance to stretching [ ].

Adequate hydration while taking creatine might minimize these uncommon risks [ ]. In a position statement, the AND, DoC, and ACSM advise that creatine enhances performance of cycles of high-intensity exercise followed by short recovery periods and improves training capacity [ 12 ].

In its position statement, the ISSN states that creatine monohydrate is the most effective nutritional supplement currently available for enhancing capacity for high-intensity exercise and lean body mass during exercise [ ].

The ISSN contends that athletes who supplement with creatine have a lower incidence of injuries and exercise-related side effects compared to those who do not take creatine [ ].

The Australian Institute of Sport supports the use of creatine for improving sports performance in suitable athletic competitions under the direction of an expert in sports medicine, but it notes that more research might be required to understand how the supplement should be used for best results [ 29 ].

In some studies, the loading dose is based on body weight e. Other, usually more expensive, forms of creatine e. Deer antler velvet consists of cartilage and epidermis from growing deer or elk antlers before ossification [ , ]. It is used as a general health aid in traditional Chinese medicine.

Several growth factors have been detected in deer antler velvet, such as IGF-1, that could promote muscle tissue growth in a similar way to the quick growth of deer antlers.

Three randomized controlled trials in a total of 95 young and middle-age men and 21 young females provide virtually no evidence that deer antler velvet supplements improve aerobic or anaerobic performance, muscular strength, or endurance [ , ].

The supplements provided no significant ergogenic effects compared with placebo. Studies have not adequately assessed the safety of deer antler velvet.

The studies cited above found no side effects in participants taking deer-antler-velvet supplements. IGF-1 is available as a prescription medication, and its reported side effects include hypoglycemia, headache, edema, and joint pain [ ]. An evaluation of six deer-antler-velvet dietary supplements that were commercially available in found that five of them contained no deer IGF-1, and four were adulterated with human IGF-1 [ ].

Only one of the six supplements contained a low level of deer IGF The research to date does not support taking deer-antler-velvet supplements to enhance exercise or athletic performance. The National Collegiate Athletic Association [ ] and the World Anti-Doping Agency [ ] ban the use of IGF-1 and its analogues in athletic competition.

DHEA is a steroid hormone secreted by the adrenal cortex. The body can convert DHEA to the male hormone testosterone; testosterone's intermediary, androstenedione; and the female hormone estradiol [ ]. Testosterone is an anabolic steroid that promotes gains in muscle mass and strength when combined with resistance training [ ].

The minimal research on DHEA's use to enhance exercise and athletic performance provides no evidence of benefit [ ]. Compared to placebo, the DHEA and androstenedione produced no statistically significant increase in strength, aerobic capacity, lean body mass, or testosterone levels [ ]. The supplement provided no benefits compared with placebo in increasing muscle strength, lean body mass, or testosterone concentrations [ ].

Studies have not adequately assessed the safety of DHEA. The two short-term studies in men described above found no side effects from the DHEA; blood lipid levels and liver function remained normal. Other studies have found that in women, use of DHEA for months significantly raises serum testosterone but not estrogen levels, which can cause acne and growth of facial hair [ ].

The research to date does not support taking DHEA supplements to enhance exercise or athletic performance. The National Collegiate Athletic Association and the World Anti-Doping Agency ban the use of DHEA [ , ]. Ginseng is a generic term for botanicals from the genus Panax.

Some popular varieties are known as Chinese, Korean, American, and Japanese ginseng. Preparations made from ginseng roots have been used in traditional Chinese medicine for millennia as a tonic to improve stamina and vitality [ ].

So-called Siberian or Russian ginseng Eleutherococcus senticosus , although unrelated to Panax ginseng, has also been used in traditional Chinese medicine to combat fatigue and strengthen the immune system [ ].

Numerous small studies, with and without placebo controls, have investigated Panax ginseng's potential to improve the physical performance of athletes, regular and occasional exercisers, and largely sedentary individuals.

In almost all cases, the studies found that Panax ginseng in various doses and preparations had no ergogenic effect on such measures as peak power output, time to exhaustion, perceived exertion, recovery from intense activity, oxygen consumption, or heart rate [ , ].

One review of studies of the effects of Siberian ginseng on endurance performance found that the five studies with the most rigorous research protocols with a total of 55 men and 24 women showed no effect of supplementation for up to 6 weeks on exercise performed for up to minutes [ ].

Short-term Panax ginseng use appears to be safe; the most commonly reported adverse effects include headache, sleep disturbances, and gastrointestinal disorders [ ]. Short-term Siberian ginseng use also appears to be safe.

The studies cited above reported no adverse effects, although other reports of clinical trials have listed insomnia as a rare side effect [ ]. The research to date provides little support for taking ginseng to enhance exercise or athletic performance [ , ].

Glutamine is a key molecule in metabolism and energy production, and it contributes nitrogen for many critical biochemical reactions [ ]. It is an EAA for critically ill patients when the body's need for glutamine exceeds its capacity to produce sufficient amounts. Few studies have examined the effect of glutamine supplementation alone as an ergogenic aid [ ].

One study randomized 31 male and female weightlifters to receive either glutamine 0. There were no significant differences between the two groups in measures of strength, torque, or lean tissue mass, demonstrating that glutamine had no effect on muscle performance, body composition, or muscle-protein degradation.

Another study compared the effect of glutamine four doses of 0. Supplementation with glutamine reduced the magnitude of strength loss, accelerated strength recovery, and diminished muscle soreness more quickly than placebo; these effects were more pronounced in the men.

Some athletes use glutamine supplements in the hope that they will attenuate exercise-induced immune impairment and reduce their risk of developing upper respiratory tract infections.

However, there is little research-based support for this benefit [ , ]. In the studies described above, the glutamine had no reported side effects.

Many patients with serious catabolic illnesses, such as infections, intestinal diseases, and burns, take glutamine safely as part of their medical care.

Daily oral doses ranging from 0. The research to date does not support taking glutamine alone to improve exercise and athletic performance [ , ]. Iron is an essential mineral and a structural component of hemoglobin, an erythrocyte protein that transfers oxygen from the lungs to the tissues, and myoglobin, a protein in muscles that provides them with oxygen.

Iron is also necessary to metabolize substrates for energy as a component of cytochromes and to dehydrogenase enzymes involved in substrate oxidation [ ]. Iron deficiency impairs oxygen-carrying capacity and muscle function, and it limits people's ability to exercise and be active [ 12 , ].

Its detrimental effects can include fatigue and lethargy, lower aerobic capacity, and slower times in performance trials [ ]. Iron balance is an important consideration for athletes who must pay attention to both iron intakes and iron losses.

Teenage girls and premenopausal women are at increased risk of obtaining insufficient amounts of iron from their diets. They require more iron than teenage boys and men because they lose considerable iron due to menstruation, and they might not eat sufficient amounts of iron-containing foods [ , ].

Athletes of both sexes lose additional iron for several reasons [ , , , ]. Physical activity produces acute inflammation that reduces iron absorption from the gut and iron use via a peptide, hepcidin, that regulates iron homeostasis.

Iron is also lost in sweat. The destruction of erythrocytes in the feet because of frequent striking on hard surfaces leads to foot-strike hemolysis. Also, use of anti-inflammatories and pain medications can lead to some blood loss from the gastrointestinal tract, thereby decreasing iron stores.

The richest dietary sources of heme iron which is highly bioavailable include lean meats and seafood. Plant-based foods—such as nuts, beans, vegetables, and fortified grain products—contain nonheme iron, which is less bioavailable than heme iron. Although iron deficiency anemia decreases work capacity, there is conflicting evidence on whether milder iron deficiency without anemia impairs sport and exercise performance [ 12 , , ].

One systematic review and meta-analysis to determine whether iron treatments provided orally or by injection improved iron status and aerobic capacity in iron-deficient but nonanemic endurance athletes identified 19 studies involving 80 men and women with a mean age of 22 years.

Iron treatments improved iron status as expected, but they did not guarantee improvement in aerobic capacity or indices of endurance performance [ ]. Another systematic review and meta-analysis compared the effects of iron supplementation with no supplementation on exercise performance in women of reproductive age [ ].

Click name to view affiliation. A strong foundation in physical conditioning and sport-specific experience, in addition to a bespoke and periodized training and nutrition program, are essential for athlete development.

Once these underpinning factors are accounted for, and the athlete reaches a training maturity and competition level where marginal gains determine success, a role may exist for the use of evidence-based performance supplements. However, it is important that any decisions surrounding performance supplements are made in consideration of robust information that suggests the use of a product is safe, legal, and effective.

The following review focuses on the current evidence-base for a number of common and emerging performance supplements used in sport. The supplements discussed here are separated into three categories based on the level of evidence supporting their use for enhancing sports performance: 1 established caffeine, creatine, nitrate, beta-alanine, bicarbonate ; 2 equivocal citrate, phosphate, carnitine ; and 3 developing.

Within each section, the relevant performance type, the potential mechanisms of action, and the most common protocols used in the supplement dosing schedule are summarized. Numerous factors contribute to peak athletic performance.

Among these, a strong foundation in physical conditioning and sport-specific experience, in addition to a bespoke and periodized training and nutrition program, the latter based predominately from whole food choices, are essential. Although an array of supplements are marketed for the enhancement of sports performance, many lack robust evidence of an ergogenic benefit.

Finally, numerous ingredients in commercial supplements, sometimes presenting as contaminants or undeclared ingredients, carry a risk of inadvertent anti-doping rule violations Baylis et al. With this in mind, athletes and their associated support teams should only consider performance supplements where a strong body of evidence supports their use as safe, legal, and effective.

The supplements of interest have been divided into three categories according to the strength of evidence supporting their use for the enhancement of sports performance. These categories include: 1 established, 2 equivocal, and 3 developing performance supplements.

There is robust evidence that the following supplements can enhance sports performance when used according to established protocols. Caffeine, a stimulant that is ubiquitously consumed in the diets of most adults, has well-established benefits for athletic performance. The mechanisms underpinning these benefits include adenosine receptor antagonism, increased endorphin release, enhanced neuromuscular function, improved vigilance and alertness, and a reduced perception of exertion during exercise for review, see Burke, ; Goldstein et al.

Caffeine supplementation is known to improve endurance capacity during time to fatigue exercise tasks—for instance, during activities such as treadmill running to exhaustion French et al.

Furthermore, ergogenic benefits are also widely reported during competitive situations, such as real or laboratory-simulated time-trial TT activities. A systematic review by Ganio et al.

In fact, such doses are likely to increase the risk of negative side effects, such as nausea, anxiousness, insomnia, and restlessness Burke, —outcomes that would clearly negate any performance-enhancing outcomes. Interestingly, similar performance outcomes are expected in both habituated caffeine users and nonusers Goldstein et al.

Low doses of caffeine consumed during endurance exercise have also been shown to enhance performance. In fact, — mg 1. The effects of caffeine on short-term, supramaximal, and repeated sprint tasks have been less well studied.

Of note, athletes who intend to use caffeine as a performance aid should trial their strategies during training or minor competitions, in order to fine-tune a protocol that achieves benefits with minimal side effects. Creatine is another widely-researched supplement, with creatine monohydrate CM being the most common form used to supplement dietary intake from meats.

Within the muscle, creatine-kinase mediates the phosphorylation of creatine to phosphocreatine PCr , a key substrate for high-intensity muscle force generation Greenhaff et al. As a result, creatine loading can acutely enhance the performance of sports involving repeated high-intensity exercise e.

There is additional, albeit equivocal, evidence of changes in cellular signaling, metabolism, and water storage associated with creatine supplementation with potential flow-on effects such as enhancements of protein synthesis, glycogen storage, and thermoregulation for review, see Cooper et al.

Therefore, there may be less well-recognized benefits of creatine supplementation for endurance sport athletes. Such protocols have been established primarily from early work investigating muscle creatine loading in males Hultman et al.

No negative health effects have been reported with the long-term use of CM up to 4 years when appropriate loading protocols are followed Schilling et al. In fact, some reports propose CM supplementation to be anti-inflammatory, and to reduce exercise-induced oxidative stress Deminice et al.

Dietary nitrate NO 3 — is a popular supplement initially found to improve oxygen uptake VO 2 kinetics during prolonged submaximal exercise Bailey et al. The ingestion of dietary NO 3 — leads to an enhanced nitric oxide NO bioavailability via the NO 3 — -nitrite-NO pathway, a reduction catalyzed initially by bacteria in the mouth and the digestive system Duncan et al.

NO plays an important role in the modulation of skeletal muscle function Jones, , with proposed mechanisms for improved exercise performance including a reduced ATP cost of muscle force production, an increased efficiency of mitochondrial respiration, increased blood flow to the muscle, and a decrease in blood flow to VO 2 heterogeneities Bailey et al.

Recently, nitrate supplementation has been proposed to enhance the function of type II muscle fibers Bailey et al. Differences in these findings may possibly relate to the lower dose of nitrate provided in the acute instance; indeed, a dose-response effect of NO 3 — supplement use has been shown previously, with higher NO 3 — doses having a greater impact on 2,m rowing performance Hoon et al.

However, the benefit of nitrate supplementation for very highly-trained elite athletes requires more research, with some Nyakayiru et al. Finally, chronic NO 3 — supplementation may facilitate training adaptations when taken prior to key sessions, with greater improvements 8.

Leafy green and root vegetables i. Performance benefits may manifest acutely i. Finally, performance benefits may be maintained for at least 15 days, if consumption of the supplement is continued for this duration Vanhatalo et al.

Beta-alanine is the rate-limiting precursor to carnosine, an endogenous intracellular muscle buffer, and one of the immediate defenses against the accumulation of protons in the contracting musculature during exercise Lancha Junior et al. Daily supplementation with 3.

Beta-alanine supplementation may not be as effective in well-trained athletes as their lesser-trained counterparts Bellinger, , partly due to a diminishing role of carnosine toward intramuscular pH regulation in individuals with an already enhanced buffering capacity.

However, the small performance changes observed in well-trained athletes to date 0. Beta-alanine dosing strategies typically involve split doses consumed over the day i.

However, in accounting for this individual variation, an in-depth analysis and summary of the available literature by Stellingwerff et al. Regardless, it is likely that an individualized approach to beta-alanine supplementation should be considered where possible.

Ingestion of sodium bicarbonate NaHCO 3 is proposed to enhance high-intensity exercise performance as an extracellular blood buffer; however, the mechanisms of action are complex Siegler et al. Although playing an important role in the maintenance of both intracellular and extracellular pH, NaHCO 3 is unable to permeate the sarcolemma, and therefore aids intracellular pH regulation indirectly by raising both extracellular pH and HCO 3 — concentrations Katz et al.

Successful supplementation protocols typically involve acute NaHCO 3 doses of 0. However, common side effects include GI upset, which may negate any performance enhancements, likely explaining the large variability in individual responses Carr, Slater, et al.

Furthermore, sodium citrate has been proposed as an alternative to NaHCO 3 , as a result of lower reported rates albeit not in all investigations of GI upset Requena et al. Potentially, the aforementioned supplement doses and performance effects are achievable from slightly-elevated dietary consumption of commonly-consumed foods and beverages i.

Regardless, it is no doubt reassuring that each of these established performance supplements can be found in various forms on the shelves and in the fridges of the local supermarket. The following supplements are also used by athletes; however, the evidence-base for their potential to enhance athletic performance is less clear.

Similar to NaHCO 3 , sodium citrate acts as a blood buffer by increasing pH in the extracellular environment, and increasing the gradient between the blood and the active muscle. Early studies trialed sodium citrate doses ranging from 0.

Here, a dose response was seen, with ergogenic benefits requiring a minimum ingestion of 0. Subsequently, a 0. The more recent discovery that the time to peak blood pH occurs — min after sodium citrate ingestion suggests that the dosing protocol should occur at a minimum of 3 hr preexercise Urwin et al.

Despite these few positive investigations, it should be noted that the ergogenic effect of sodium citrate ingestion remains equivocal, with a previous meta-analysis highlighting a negligible benefit 0. Considering the detrimental side effects from both NaHCO 3 and citrate, and the potential for limited benefits with the latter, athletes and support staff are encouraged to carefully trial the use of these blood buffers in training before implementing an individualized and bespoke protocol in a competition setting.

Numerous hypotheses have been proposed to support the potential benefits of phosphate supplementation on athletic performance see Buck et al. The proposed mechanisms underpinning these benefits include an enhanced rate of ATP and PCr resynthesis Kreider, ; improved buffering capacity to support high rates of anaerobic glycolysis Kreider, ; improvement of myocardial contractility leading to increased cardiac efficiency Kreider et al.

Overall, there is equivocal evidence of performance enhancement from phosphate supplementation. In some instances, phosphate has been shown to enhance VO 2max Cade et al. However, in the case of repeated sprints, the magnitude of benefit has been shown to be varied and unclear Kopec et al, Finally, there is also a large amount of contrary evidence from the same physiological and performance measures that suggests phosphate supplementation in isolation, or in combination with other buffer agents has no impact on exercise capacity or performance outcomes Brewer et al.

No doubt, the lack of clear consensus defined by this collective work is explained by variations in the supplement protocol used i.

as well as individual responses to the supplement itself Peeling, This is often associated with GI distress Cade et al. Nevertheless, current evidence regarding the efficacy of phosphate supplementation remains unclear, since there exists no evidence to suggest an accumulation of this supplement in the muscle, where a number of the reported mechanism are suggested to take effect.

As such, the use of this supplement for enhanced athletic performance is likely questionable, with further research needed to fully explore its true effect. If considered for use, individual responses should be thoroughly trialed prior to using this supplement in a competition setting.

Increased muscle carnitine stores via supplementation with L-carnitine are postulated to spare glycogen, via increased fat oxidation, at lower exercise intensities, and to promote more efficient carbohydrate oxidation and reduced lactate accumulation at higher intensities, delaying the onset of fatigue during endurance-based activity.

Research on L-carnitine supplementation has shown equivocal outcomes. Marconi et al. Of note, the lack of performance effect seen in these studies may likely result from the fact that muscle carnitine levels do not seem to increase when using these standard supplement protocols i.

More recently, Novakova et al. Importantly, there was no effect on muscle function, energy metabolism, or VO 2 during either submaximal or maximal exercise tests. It is likely that the lack of efficacy of oral L-carnitine supplementation in many studies is due to its low bioavailability and failure to increase muscle carnitine stores.

However, Stephens, Evans, et al. In a follow-up study Wall et al. Therefore, given the limited research in this space, and the considerable effort needed to implement such a protocol, further investigation is needed to clarify the efficacy and safety of following these prolonged supplement regimes.

This section covers supplements which are emerging in both their popularity and the evidence base for athletic performance benefits. However, more work is needed before conclusive recommendations can be made on their use, and there may be some differences in the principles or mechanisms by which they could be of value.

The performance supplements outlined in the prior sections are presented in view of a strong evidence base to reflect a direct impact on athletic performance through the augmentation of various rate-limiting processes. However, other supplements may have an indirect impact on performance via their ability to support the training process, through their influence on factors such as inflammatory modulation, oxidative stress, and signaling pathways for adaptation, or their ability to support repetitive performance by restoring homeostasis between two exercise bouts.

Such an outcome may impact athlete performance—for instance, if the supplement protocol targets an improvement in fatigue resistance during heavy competition schedules. Similarly, food polyphenols may act in a comparable way, possessing strong anti-oxidant and anti-inflammatory properties see Tsao, that may be beneficial to exercise recovery.

For instance, the high anthocyanin content of tart Montmorency cherries has been shown to reduce the inflammatory and oxidative stress responses to marathon running Howatson et al. Of note, only blood biomarkers were presented in these aforementioned studies to suggest such a benefit and, therefore, these outcomes should be further confirmed by muscle analysis in future research.

Of note, there are several issues that make it more difficult to substantiate the performance benefits of these supplements. One factor is that it may take a lengthy period before better recovery between exercise bouts or better support of training leads to a detectable improvement in competition performance.

For example, previous research on supplementation with anti-oxidant vitamins i. As such, the ultimate benefit of the use of these supplements may depend on how and when they are used; for example, they might be used in scenarios of repeated competition events to reduce exercise perturbations and enhance recovery and subsequent performance, but avoided during training bouts where optimal adaptation is driven by full exposure to oxidative or inflammatory stress.

Alternatively, some supplements may affect a number of body systems, with positive effects on one system counteracting the minor negative effects on another. For example, although they are considered to have anti-oxidant properties, some polyphenol subclasses e.

Furthermore, numerous food polyphenols are also suggested to have a direct effect on performance, potentially a result of mechanisms relevant to flow mediated dilatation, NO production, and adenosine receptor antagonism effects Somerville et al.

However, clearly in its infancy, there exists a need for further research exploring these emerging supplements to fully examine the effects and potential efficacy of their ability to support the training process, and to provide a direct positive impact on athletic performance.

This review summarizes the evidence for a number of commonly-used supplements, ingested with the aim of enhancing athletic performance.

This should be further viewed in light of the marginal, but often important, gains that may be achieved through sound use of these products, as well as practical considerations such as a lack of uniform tolerance and response to a given supplement.

As such, any use of performance supplements should be thoroughly trialed in training before implementation into a competition environment, since, in some scenarios, outcomes ranging from a lack of efficacy to deleterious responses may outweigh any expected performance enhancement.

Astorino , T. Efficacy of acute caffeine ingestion for short-term high-intensity exercise performance: A systematic review. PubMed doi Baguet , A.

Important role of muscle carnosine in rowing performance. Journal of Applied Physiology , 4 , — Bailey , S. Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. Journal of Applied Physiology , 1 , — Inorganic nitrate supplementation improves muscle oxygenation, O 2 uptake kinetics, and exercise tolerance at high but not low pedal rates.

Journal of Applied Physiology , 11 , — Dietary nitrate supplementation reduces the O 2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans.

Barnett , C. Effect of L-carnitine supplementation on muscle and blood carnitine content and lactate accumulation during high-intensity sprint cycling. International Journal of Sport Nutrition, 4 3 , — Baylis , A. Inadvertent doping through supplement use by athletes: Assessment and management of the risk in Australia.

International Journal of Sport Nutrition and Exercise Metabolism, 11 3 , — Bell , P. Montmorency cherries reduce the oxidative stress and inflammatory responses to repeated days high-intensity stochastic cycling.

Nutrients, 6 12 , — Bellar , D. Effects of low-dose caffeine supplementation on early morning performance in the standing shot put throw. European Journal of Sport Science, 12 1 , 57 — Bellinger , P.

Beta-Alanine supplementation for athletic performance: An update. Benesch , R. Intracellular organic phosphates as regulators of oxygen release by haemoglobin. Nature, , — Boorsma , R. Beetroot juice supplementation does not improve performance of elite m runners. Braakhuis , A.

Impact of dietary antioxidants on sport performance: A review. Sports Medicine, 45 7 , — Branch , J. Effect of creatine supplementation on body composition and performance: A meta-analysis.

International Journal of Sport Nutrition and Exercise Metabolism, 13 2 , — Brewer , C. Effect of repeated sodium phosphate loading on cycling time-trial performance and VO2peak. International Journal of Sport Nutrition and Exercise Metabolism, 23 2 , — Effect of sodium phosphate supplementation on cycling time trial performance and VO2 1 and 8 days post loading.

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By continuing to push yourself with repeated training, you can further augment this adaption and increase muscle mass, which will burn more fuel calories at rest. Consider how long it takes someone to run a mile before training compared with how long it takes after training.

Regardless of the time difference in running the mile, the number of calories burned will be similar. The major difference is the energy-yielding macronutrient distribution of fuels oxidized, the energy systems used, and the calories burned divided by the amount of time to run the mile.

The trained person will oxidize more fat, feel better during the run because of less lactic acid production, and burn more calories per unit of time. The result is usually an enjoyable experience during which mileage and calorie expenditure is increased, thus improving metabolic health and assisting in the maintenance of a healthy body weight.

When continued training promotes metabolic adaptation that shifts the crossover point to the right, the athlete benefits from the same metabolic advantages as the nonathlete but to a greater degree. But the most important metabolic benefit of the crossover adaptation for the athlete is not weight and body composition management—the most important benefit is the ability to preserve and protect limited carbohydrate stores until the highest-intensity effort is required to compete in an athletic event.

Because carbohydrate stores in the body are limited in muscle tissue, and occur in a relatively small amount in the liver, the preservation of this fuel source for anaerobic system activity to fuel ATP generation is crucial to high-intensity performance. Think of a trained distance runner metabolically capable of tapping primarily into fat stores to fuel much of the ATP demand for most of a race.

When it is important for the runner to run up hills or overtake other runners in the final portion of the race, the increased intensity and increased ATP demand will need to be met anaerobically with the only fuel that the anaerobic system can use—carbohydrate.

If this runner did not adequately prepare for the race by consuming enough carbohydrate leading up to the race, their capacity to produce ATP anaerobically will be compromised and will negatively affect performance. Consuming nitrate-rich vegetables such as spinach, arugula, and beetroot juice or beetroot supplements may enhance athletic performance.

Several studies have documented performance enhancement and mechanisms related to metabolism. For some athletes, nitrate significantly improves skeletal muscle oxygen uptake and mitochondrial use of oxygen. Nitrate may also reduce the amount of oxygen needed to generate ATP during submaximal aerobic exercise and reduce ATP demand for muscles to produce force Because these benefits may improve exercise tolerance and aerobic system efficiency, dietary nitrate supplementation may be beneficial for both trained athletes and novice athletes who do not have a highly adapted aerobic energy system To learn more about the dietary nitrate supplementation, refer to chapter 9.

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Home Excerpt Discover the benefits of training on health and athletic performance. Travis Thomas. Putting It Into Perspective Metabolic Effect of Dietary Nitrate Consuming nitrate-rich vegetables such as spinach, arugula, and beetroot juice or beetroot supplements may enhance athletic performance.

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Drishti Thakkar is a graduate student in the Faculty of Information at U of T who analyzed the trial data and compiled the results as part of an undergraduate project in nutritional sciences. The research was supported by the Canadian Institutes of Health Research, Canadian Foundation for Dietetic Research, Nutrigenomix, the Coca Cola Company and Mitacs.

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