Athletic Performance

Also indexed as: Endurance, Exercise, Fitness, Training

Reach the peak of athletic performance. Take your game to the next level by learning some fitness essentials. According to research or other evidence, the following self-care steps may be helpful:

Eat more carbs
Supply the body with efficient energy fuel found in grains, starchy vegetables, fruits, low-fat dairy products, and carbohydrate-replacement drinks

Get enough water and electrolytes
Water is crucial for all sports activities—electrolytes are only important for extreme endurance exercise

Check out creatine monohydrate
Take 15 to 20 grams a day of this supplement for five or six days to improve performance of high-intensity, short-duration exercise (like sprinting) or sports with alternating low- and high-intensity efforts

Take a multivitamin
When your diet isn’t enough, extra vitamins and minerals will help your body get the nutrition it needs for exercise

Try vitamin C
Take 400 mg a day for several days before and after intense exercise to reduce pain and speed muscle strength recovery

These recommendations are not comprehensive and are not intended to replace the advice of your doctor or chemist. Continue reading the full athletic performance article for more in-depth, fully-referenced information on medicines, vitamins, herbs, and dietary and lifestyle changes that may be helpful.

About athletic performance

Aside from training, nutrition may be the most important influence on athletic performance.¹ However, in seeking a competitive edge, athletes are often susceptible to fad diets or supplements that have not been scientifically validated. Nevertheless, there is much useful research to guide the exerciser toward optimum health and performance.

Product ratings for athletic performance

Science Ratings	Nutritional Supplements	Herbs
	Creatine monohydrate (for high-intensity, short duration exercise or sports with alternating low- and high-intensity efforts) Multivitamin-mineral supplements (if deficient) Vitamin C (to reduce pain and speed muscle strength recovery after intense exercise)
	Arginine alpha-ketoglutarate (AAKG) Citrate (for high-intensity, short- to intermediate-duration exercise) Creatine monohydrate (for non-weight bearing endurance exercise) DHEA (for improving strength in older men only) Electrolyte replacement (for ultra-endurance competition only) Glutamine (for reducing risk of post-exercise infection only) HMB (for improving body composition with strength training in untrained people only) Iron (for iron deficiency only) Phosphatidylserine (to enhance endurance in young active men) Pyruvate (for exercise performance) Sodium bicarbonate (for performance enhancement in events of specific durations only) Soya (for exercise recovery only) Vitamin C (for deficiency only) Vitamin E (for exercise recovery and high-altitude exercise performance only) Whey protein	Asian ginseng (for endurance exercise and muscle strength only) Eleuthero Rhodiola (to improve endurance)
	Alpha-ketoglutarate (AKG) Arginine/Ornithine (for body composition and strength) Aspartic acid Beta-sitosterol/Beta-sitosterol glucoside (in combination for reducing the risk of post-exercise infection) Branched-chain amino acids (for high altitude and extreme temperature, for reducing the risk of post-exercise infection, or for preventing decline of mental functioning during exercise) Chromium CLA Coenzyme Q10 Copper Eucalyptus (topical) Gamma oryzanol L-carnitine Magnesium Medium chain triglycerides Methoxyisoflavone Octacosanol Ornithine alpha-ketoglutarate (OKG) Phosphorus Pyruvate (for improving body composition with strength training in untrained people only) Ribose Vitamin B-complex Zinc	American ginseng Cayenne (topical capsaicin) Eucalyptus (topical) Guaraná Kola Tribulus Yohimbe
See also: Homoeopathic Remedies for Athletic Performance
Reliable and relatively consistent scientific data showing a substantial health benefit. Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit. For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.

Medical options

Athletic performance may be improved by ensuring adequate and balanced nutrition, sufficient fluid intake, and proper rest. The avoidance of performance-reducing drugs such as alcohol and tobacco is also commonly recommended.

Dietary changes that may be helpful

Calories
Calorie requirements for athletes depend on the intensity of their training and performance. The athlete who trains to exhaustion on a daily basis needs more fuel than one who performs a milder regimen two or three times per week. Calorie requirements can be as much as 23 to 39 calories per pound of body weight per day for the training athlete who exercises vigorously for several hours per day.² ³ Many athletes compete in sports having weight categories (such as wrestling and boxing), sports that favour small body size (such as gymnastics and horse racing), or sports that may require a specific socially accepted body shape (such as figure skating). These athletes may feel pressured to restrict calories to extreme degrees to gain a competitive edge.⁴ Excessive calorie restriction can result in chronic fatigue, sleep disturbances, reduced performance, impaired ability for intensive training, and increased vulnerability to injury.⁵

Carbohydrates
Carbohydrates are the most efficient fuel for energy production and can also be stored as glycogen in muscle and liver, functioning as a readily available energy source for prolonged, strenuous exercise. For these reasons, carbohydrates may be the most important nutrient for sports performance.⁶ Depending on training intensity and duration, athletes require up to 4.5 grams of carbohydrates per day per pound of body weight or 60 to 70% of total dietary calories from carbohydrates, whichever is greater.⁷ ⁸ Emphasizing grains, starchy vegetables, fruits, low-fat dairy products, and carbohydrate-replacement beverages, along with reducing intake of fatty foods, results in a relatively high-carbohydrate diet.

Carbohydrate beverages should be consumed during endurance training or competition (30 to 70 grams of carbohydrate per hour) to help prevent carbohydrate depletion that might otherwise occur near the end of the exercise period. Standard sport drinks containing 6 to 8% carbohydrates can be used during exercise to support both carbohydrate and fluid needs, but these should not contain large amounts of fructose, which can cause gastrointestinal distress.⁹ At the end of endurance exercise, body carbohydrate stores must be replaced to prepare for the next session. This replacement can be achieved most rapidly if 40 to 60 grams of carbohydrate are consumed right after exercise, repeating this intake every hour for at least five hours after the event.¹⁰ High-density carbohydrate beverages containing 20 to 25% carbohydrate are useful for immediate post-exercise repletion.

Adding protein to carbohydrate intake immediately after exercise may be helpful for improving recovery of glycogen (carbohydrate) stores after exercise according to some,¹¹ ¹² ¹³ though not all,¹⁴ ¹⁵ ¹⁶ ¹⁷ ¹⁸ controlled studies. It appears that adding protein during the post-exercise period is not necessary when carbohydrate intake is high enough (about 0.55 grams per pound of body weight).¹⁹

Carbohydrate loading, or “super-compensation,” is a pre-event strategy that improves performance for some endurance athletes.²⁰ ²¹ Carbohydrate-loading can be achieved by consuming a 70% carbohydrate diet (or 4.5 grams per pound of body weight) for three to five days before competition, while gradually reducing training time, and ending with a day of no training while continuing the diet until the event date.

Glycaemic index
The glycaemic index (GI) is a measure of the ability of a food to raise blood sugar levels after it is eaten. Attention to the GI of carbohydrate sources may be helpful for increasing sports performance. Within one hour before exercise, consuming low GI carbohydrates (such as most fruits, pasta, pulses, or rice) provides carbohydrate without triggering a rapid rise in insulin that could result in hypoglycaemia and prevent release of energy sources from fat cells.²² Some controlled studies of cycling endurance have found that eating a pre-exercise meal of low-GI foods (lentils, rolled oats, or a combination of low GI foods) is more effective than consuming high-GI foods (potatoes, puffed rice, or a combination of high GI foods),²³ ²⁴ ²⁵ but most studies have found no significant advantage of low GI foods or fructose (a low-GI sugar) compared with other carbohydrate sources in a pre-exercise meal. ²⁶ ²⁷ ²⁸ ²⁹ ³⁰ ³¹ ³² ³³ After exercise, on the other hand, high-GI foods and beverages may be most helpful for quickly restoring depleted glycogen stores.³⁴

Protein
Protein requirements are often higher for both strength and endurance athletes than for people who are not exercising vigorously; however, the increased food intake needed to supply necessary calories and carbohydrates also supplies extra protein. As long as the diet contains at least 12 to 15% of calories as protein, or up to 0.75 grams per day per pound of body weight, protein supplements are neither necessary, nor likely to be of benefit.³⁵ ³⁶ Concerns have been raised that the very high-protein diets sometimes used by body builders could put stress on the kidneys, potentially increasing the risk of kidney disease later in life. A preliminary study of male athletes consuming at least 2.77 grams per pound of body weight per day showed no evidence of kidney impairment; however, the study was limited to one month, and evidence of long-term kidney problems associated with chronic protein loading were not examined.³⁷

Preliminary studies have suggested that increased protein intake may have biological effects that could improve muscle growth resulting from strength training, especially if liquid supplements (typically containing at least 6 grams of protein or amino acids in addition to varying amounts of carbohydrate) are taken either immediately after exercise or just before exercise.³⁸ ³⁹ ⁴⁰ ⁴¹ ⁴² ⁴³ ⁴⁴ However, controlled studies have found no advantage of protein supplementation (up to about 100 grams per day or about 14 grams immediately following exercise) for improving strength or body composition as long as the diet already supplies typical amounts of protein and calories.⁴⁵ ⁴⁶ ⁴⁷

Fat
Some athletes have speculated that consuming a high-fat diet for two or more weeks prior to endurance competition might cause the body to shift its fuel utilization toward more abundant fat stores ("fat adaptation").⁴⁸ However, neither short-term nor long-term use of high-fat diets has been found to improve endurance performance compared with high-carbohydrate diets, and may even be detrimental due to depletion of glycogen stores.⁴⁹ ⁵⁰

Following a high-fat diet with at least 24 hours of high carbohydrate intake has been suggested as a way to achieve fat adaptation while restoring glycogen levels before endurance competition.⁵¹ ⁵² While this concept is supported by physiological studies on athletes, no actual performance enhancement was shown when athletes were tested in competitive situations after a five- to six-day high-fat diet followed by 24 hours of high carbohydrate intake.⁵³ ⁵⁴ ⁵⁵ However, one controlled study found a small, significant benefit of ten days of high fat intake followed by three days of high carbohydrate intake.⁵⁶

Water
Water is the most abundant substance in the human body and is essential for normal physiological function. Water loss due to sweating during exercise can result in decreased performance and other problems. Fluids should be consumed prior to, during, and after exercise, especially when extreme conditions of climate, exercise intensity, and exercise duration exist.⁵⁷ Approximately two glasses of fluid should be consumed two hours before exercise and at regular intervals during exercise; fluid should be cool, not cold (59 to 72° F, 15 to 22.2° C). Flavored sports drinks containing electrolytes are not necessary for fluid replacement during brief periods of exercise, but they may be more effective in encouraging the athlete to drink frequently and in larger amounts.⁵⁸ ⁵⁹

Lifestyle changes that may be helpful

Many athletes use exercise and weight-modifying diets as tools to change their body composition, assuming that a lower percentage of body fat and/or higher lean body mass is desirable in any sport. There is no single standard for body weight and body composition that applies to all types of athletic activities. Different sports, even different roles in the same sport (e.g., running vs. blocking in football), require different body types. These body types are largely determined by genetics. However, within each athlete’s genetic predisposition, variations result from diet and exercise that may affect performance. In general, excess weight is a disadvantage in activities that require quickness and speed. However, brief, intense bursts of power depend partly on muscle size, so this type of activity may favour athletes with greater muscle mass. On the other hand, participants in endurance sports, which require larger energy reserves, should not attempt to lower their body fat so much as to compromise their performance.⁶⁰

Vitamins that may be helpful

Arginine alpha-ketoglutarate
Arginine alpha-ketoglutarate (AAKG) is a compound made from the amino acid L-arginine and alpha-ketoglutarate (AKG) a substance formed in the body’s energy-generating process. It has been speculated that AAKG may increase production in muscles of nitric oxide, a substance known to have blood-flow-enhancing effects. A double-blind study gave trained weight lifters either 4 grams of AAKG or a placebo three times a day during an eight-week weight-training regimen. AAKG had no effect on body composition but did improve measures of strength and short-term power performance.⁶¹

Creatine
Creatine (creatine monohydrate) is used in muscle tissue for the production of phosphocreatine, a factor in the formation of ATP, the source of energy for muscle contraction and many other functions in the body.⁶² ⁶³ Creatine supplementation increases phosphocreatine levels in muscle, especially when accompanied by exercise or carbohydrate intake.⁶⁴ ⁶⁵ It may also increase exercise-related gains in lean body mass, though it is unclear how much of these gains represents added muscle tissue and how much is simply water retention.⁶⁶

Over 40 double-blind or controlled studies have found creatine supplementation (typically 136 mg per pound of body weight per day or 15 to 25 grams per day for five or six days) improves performance of either single or repetitive bouts of short-duration, high-intensity exercise lasting under 30 seconds each.⁶⁷ ⁶⁸ ⁶⁹ ⁷⁰ ⁷¹ ⁷² ⁷³ Examples of this type of exercise include weightlifting; sprinting by runners, cyclists, or swimmers; and many types of athletic training regimens for speed and power. About 15 studies did not report enhancement by creatine of this type of performance. These have been criticized for their small size and other research design problems, but it is possible that some people, especially elite athletes, are less likely to benefit greatly from creatine supplementation.⁷⁴

Fewer studies have investigated whether creatine supplementation benefits continuous high- intensity exercise lasting 30 seconds or longer. Five controlled studies have found creatine beneficial for this type of exercise,⁷⁵ but one study found no benefit on performance of a military obstacle course run.⁷⁶ Most studies of endurance performance have found no advantage of creatine supplementation, except perhaps for non-weight bearing exercise such as cycling. ⁷⁷ ⁷⁸ ⁷⁹

Long-term use of creatine supplementation is typically done using smaller daily amounts (2 to 5 grams per day) after an initial loading period of several days with 20 grams per day. Very little research has been done to investigate the exercise performance effects of long-term creatine supplementation. One study reported that long-term creatine supplementation improved sprint performance.⁸⁰ Four controlled long-term trials using untrained women,⁸¹ trained men,⁸² or untrained older adults found that creatine improved gains made in strength and lean body mass from weight-training programmes.⁸³ ⁸⁴ However, two controlled trials found no advantage of long-term creatine supplementation in weight-training football players.⁸⁵ ⁸⁶

Creatine supplementation appears to increase body weight and lean body mass or fat-free mass, but these measurements do not distinguish between muscle growth and increased water content of muscle.⁸⁷ ⁸⁸ A few double-blind studies using more specific muscle measurements have been done and found that combining creatine supplementation with strength training over several weeks does produce greater increases in muscle size compared with strength training alone.⁸⁹ ⁹⁰ ⁹¹

Multivitamin-mineral supplements
Many athletes do not eat an optimal diet, especially when they are trying to control their weight while training strenuously.⁹² These athletes may experience micronutrient deficiencies that, even if marginal, could affect performance or cause health problems.⁹³ ⁹⁴ ⁹⁵ ⁹⁶ However, athletes who receive recommended daily allowances of vitamins and minerals from their diet do not appear to benefit from additional multivitamin-mineral supplements with increased performance.⁹⁷ ⁹⁸ ⁹⁹

Very little research has been done to evaluate the ergogenic effects of most vitamins or minerals other than those discussed in this article. Supplementation with selenium (180 mcg per day for 10 weeks) had no effect on the results of endurance training in one double-blind trial.¹⁰⁰ Vanadyl sulphate, a form of vanadium that may have an insulin-like action, was given to weight-training athletes in a double-blind trial, using 225 mcg per pound of body weight per day, but no effect on body composition was seen after 12 weeks, and effects on strength were inconsistent.¹⁰¹ The importance of other individual vitamins and minerals is discussed elsewhere in this section.

Antioxidants
Most research has demonstrated that strenuous exercise increases production of harmful substances called free radicals, which can damage muscle tissue and result in inflammation and muscle soreness. Exercising in cities or smoggy areas also increases exposure to free radicals. Antioxidants, including vitamin C and vitamin E, neutralize free radicals before they can damage the body, so antioxidants may aid in exercise recovery. Regular exercise increases the efficiency of the antioxidant defence system, potentially reducing the amount of supplemental antioxidants that might otherwise be needed for protection. However, at least theoretically, supplements of antioxidant vitamins may be beneficial for older or untrained people or athletes who are undertaking an especially vigorous training protocol or athletic event.¹⁰² ¹⁰³

Placebo-controlled research, some of it double-blind, has shown that taking 400 to 3,000 mg of vitamin C per day for several days before and after intense exercise may reduce pain and speed up muscle strength recovery.¹⁰⁴ ¹⁰⁵ ¹⁰⁶ However, taking vitamin C only after such exercise was not effective in another double-blind study.¹⁰⁷ While some research has reported that vitamin E supplementation in the amount of 800 to 1,200 IU per day reduces biochemical measures of free radical activity and muscle damage caused by strenuous exercise,¹⁰⁸ ¹⁰⁹ ¹¹⁰ several studies have not found such benefits,¹¹¹ ¹¹² ¹¹³ ¹¹⁴ and no research has investigated the effect of vitamin E on performance-related measures of strenuous exercise recovery. A combination of 90 mg per day of coenzyme Q10 and a very small amount of vitamin E did not produce any protective effects for marathon runners in one double-blind trial,¹¹⁵ while in another double-blind trial a combination of 50 mg per day of zinc and 3 mg per day of copper significantly reduced evidence of post-exercise free radical activity.¹¹⁶

In most well-controlled studies, exercise performance has not been shown to improve following supplementation with vitamin C, unless a deficiency exists, as might occur in athletes with unhealthy or irrational eating patterns.¹¹⁷ ¹¹⁸ Similarly, vitamin E has not benefited exercise performance, ¹¹⁹ ¹²⁰ except possibly at high altitudes. ¹²¹ ¹²²

Alkalinising agents
The use of alkalinising agents, such as sodium bicarbonate, sodium citrate, and phosphate salts (potassium phosphate, sodium acid phosphate, and tribasic sodium phosphate) to enhance athletic performance is designed to neutralize the acids produced during exercise that may interfere with energy production or muscle contraction.¹²³ Some double-blind studies, though not all, have found that sodium bicarbonate or sodium citrate typically improves exercise performance for events lasting either 1 to10 minutes or 30 to 60 minutes.¹²⁴ ¹²⁵ ¹²⁶ ¹²⁷ ¹²⁸ ¹²⁹ ¹³⁰ ¹³¹ ¹³² The amounts used are 115 to 180 mg of sodium bicarbonate or 135 to 225 mg of sodium citrate per pound of body weight. These amounts are dissolved in at least two cups of fluid and are taken either as a single ingestion at least one hour before exercise or divided into smaller amounts and taken over several hours before exercise. Performance during periods of less than one minute or between 10 and 30 minutes is not improved by taking alkalinising agents.¹³³ ¹³⁴ ¹³⁵ ¹³⁶ ¹³⁷ Sodium citrate may be preferable to sodium bicarbonate because it causes less gastrointestinal upset.¹³⁸ Another alkalinising agent, phosphate salts, has been investigated primarily as an endurance performance enhancer, with very inconsistent results.¹³⁹ ¹⁴⁰

DHEA
Dehydroepiandrosterone (DHEA) is a hormone produced by the adrenal glands that is used by the body to make the male sex hormone testosterone. In one double-blind trial, 100 mg per day of DHEA was effective for improving strength in older men,¹⁴¹ but 50 mg per day was ineffective in a similar study of elderly men and women.¹⁴² DHEA has not been effective for women or younger men in other studies.¹⁴³ ¹⁴⁴

Electrolytes
Electrolyte replacement is not as important as water intake in most athletic eneavours. It usually takes several hours of exercise in warm climates before sodium depletion becomes significant and even longer for depletions of potassium, chloride, and magnesium to occur.¹⁴⁵ However, the presence of sodium in fluids will often make it easier to drink as well as to retain more fluid.¹⁴⁶ Athletes participating in several hours of exercise, especially in hot, humid conditions, should use sodium-containing fluids to reduce the risk of performance-diminishing and possibly dangerous declines in blood sodium levels.¹⁴⁷ ¹⁴⁸

Glutamine
The amino acid glutamine appears to play a role in several aspects of human physiology that might benefit athletes, including their muscle function and immune system.¹⁴⁹ Intense exercise lowers blood levels of glutamine, which can remain persistently low with overtraining.¹⁵⁰ Glutamine supplementation raises levels of growth hormone at an intake of 2 grams per day,¹⁵¹ an effect of interest to some athletes because of the role of growth hormone in stimulating muscle growth,¹⁵² and glutamine, given intravenously, was found to be more effective than other amino acids at helping replenish muscle glycogen after exercise.¹⁵³ However, glutamine supplementation (30 mg per 2.2 pounds body weight) has not improved performance of short-term, high-intensity exercise such as weightlifting or sprint cycling by trained athletes,¹⁵⁴ ¹⁵⁵ and no studies on endurance performance or muscle growth have been conducted. Although the effects of glutamine supplementation on immune function after exercise have been inconsistent,¹⁵⁶ ¹⁵⁷ double-blind trials giving athletes glutamine (5 grams after intense, prolonged exercise, then again two hours later) reported 81% having no subsequent infection compared with 49% in the placebo group.¹⁵⁸

Phosphatidylserine
In a double-blind study of active young men, supplementation with 750 of soybean-derived phosphatidylserine per day for 10 days increased the time the men could exercise until exhaustion by approximately 25%.¹⁵⁹ Longer studies are needed to determine whether this effect would persist with continued supplementation.

HMB
HMB (beta hydroxy-beta-methylbutyrate) is a metabolite (breakdown product) of leucine, one of the essential branched-chain amino acids. Biochemical and animal research show that HMB has a role in protein synthesis and might, therefore, improve muscle growth and overall body composition when given as a supplement. However, double-blind human research suggests that HMB may only be effective when combined with an exercise programme in people who are not already highly trained athletes. Double-blind trials found no effect of 3 to 6 grams per day of HMB on body weight, body fat, or overall body composition in weight-training football players or other trained athletes.¹⁶⁰ ¹⁶¹ ¹⁶² ¹⁶³ ¹⁶⁴ However, one double-blind study found that 3 grams per day of HMB increased the amount of body fat lost by 70-year old adults who were participating in a strength-training programme for the first time.¹⁶⁵ A double-blind study of young men with no strength-training experience reported greater improvements in muscle mass (but not in percentage body fat) when HMB was used in the amount of 17 mg per pound of body weight per day.¹⁶⁶ However, another group of men in the same study given twice as much HMB did not experience any changes in body composition.

Inosine
Inosine is a nucleic acid derivative that appears in exercising muscle tissue. Its role in various cellular functions has led to suggestions that it may have ergogenic effects.¹⁶⁷ However, three controlled studies demonstrated no beneficial effects on performance and suggested that inosine may impair some aspects of exercise performance.¹⁶⁸ ¹⁶⁹ ¹⁷⁰ Therefore, use of inosine is discouraged.

Iron
Iron is important for an athlete because it is a component of haemoglobin, which transports oxygen to muscle cells. Some athletes, especially women, do not get enough iron in their diet. In addition, for reasons that are unclear, endurance athletes, such as marathon runners, frequently have low body-iron levels.¹⁷¹ ¹⁷² ¹⁷³ However, anaemia in athletes is often not due to iron deficiency and may be a normal adaptation to the stress of exercise.¹⁷⁴ Supplementing with iron is usually unwise unless a deficiency has been diagnosed. People who experience undue fatigue (an early warning sign of iron deficiency) should have their iron status evaluated by a doctor. Athletes who are found to be iron deficient by a physician are typically given 100 mg per day until blood tests indicate they are no longer deficient. Supplementing iron-deficient athletes with 100 to 200 mg per day of iron increased aerobic exercise performance in some,¹⁷⁵ ¹⁷⁶ ¹⁷⁷ though not all,¹⁷⁸ ¹⁷⁹ double-blind studies. A recent double-blind trial found that iron-deficient women who took 20 mg per day of iron for six weeks were able to perform knee strength exercises for a longer time without muscle fatigue compared with those taking a placebo.¹⁸⁰

Protein
Certain amino acids, the building blocks for protein, might be ergogenic aids as discussed in this article. However, while athletes have an increased need for protein compared with non-exercising adults, the maximum amount of protein suggested by many researchers—0.75 grams per pound of body weight per day—is already in the diet of most athletes as long as they are not restricting calories. Preliminary studies have suggested that supplementing with combinations of amino acids, typically along with carbohydrate, immediately after exercise increases muscle protein synthesis.¹⁸¹ ¹⁸² ¹⁸³ ¹⁸⁴ ¹⁸⁵ However, long-term controlled trials in young adult men,¹⁸⁶ older men,¹⁸⁷ and women have found no benefits in strength gains from supplementing with amino acids after weight training exercise.¹⁸⁸

In one preliminary study, elderly men participating in a 12-week strength training programme took a liquid supplement containing 10 grams of protein (part of which was soya protein), 7 grams of carbohydrate, and 3 grams of fat either immediately following exercise or two hours later.¹⁸⁹ Men taking the supplement immediately following exercise experienced significantly greater gains in muscle growth and lean body mass than those supplementing two hours later, but strength gains were no different between the two groups. A controlled study of female gymnasts found that adding 0.45 grams of soya protein (0.45 grams per pound of body weight per day) to a diet that was adequate in protein during a four-month training programme did not improve lean body mass compared with a placebo.¹⁹⁰ No research has compared different sources of protein to see whether one source, such as soya protein, has a better or more consistent effect on exercise recovery or the results of strength training.

Animal studies suggest that whey protein can increase gains in lean body mass resulting from exercise.¹⁹¹ A controlled trial found that six weeks of strength training while taking 1.2 grams of whey protein per 2.2 of pounds body weight per day resulted in greater gains in lean body mass, but improved only one out of four strength tests.¹⁹² Another controlled study found that people taking 20 grams per day of whey protein for three months performed better on a test of short-term intense cycling exercise than people taking a similar amount of milk protein (casein).¹⁹³ However, a double-blind trial found that men taking 1.5 grams per 2.2 lbs of body weight per day of predigested whey protein for 12 weeks along with a strength training exercise programme gained only half as much lean body mass and had significantly smaller increases in strength compared with men using a similar amount of predigested casein along with strength training.¹⁹⁴ A controlled study of HIV-infected women found that adding whey protein to strength training exercise was no more effective than exercise alone for increasing strength or improving body composition.¹⁹⁵

Pyruvate
One group of researchers in two small, controlled trials has reported that 100 grams of a combination of dihydroxyacetone and pyruvate enhanced the endurance of certain muscles in untrained men.¹⁹⁶ ¹⁹⁷ Three controlled studies of untrained individuals using a combination of 6 to 10 grams per day of pyruvate and an exercise programme reported greater effects on weight loss and body fat compared with those taking a placebo with the exercise programme.¹⁹⁸ ¹⁹⁹ ²⁰⁰ However, in a study of healthy untrained women undergoing an exercise programme, supplementing with 5 grams of pyruvate twice a day had no effect on exercise performance.²⁰¹ Studies of pyruvate supplementation on exercise performance in trained athletes have also failed to demonstrate any beneficial effect. Seven grams per day did not improve aerobic exercise performance in cyclists,²⁰² and an average of 15 grams per day did not improve anaerobic performance or body composition in football players.²⁰³ More recently, evidence has appeared casting doubt on the ability of high levels (an average exceeding 15 grams per day depending upon body weight) of pyruvate to improve exercise capacity in a weight-lifting study.²⁰⁴

Zinc
Exercise increases zinc losses from the human body, and severe zinc deficiency can compromise muscle function.²⁰⁵ ²⁰⁶ Athletes who do not eat an optimal diet, especially those who are trying to control their weight or use fad diets while exercising strenuously, may become deficient in zinc to the extent that performance or health is compromised.²⁰⁷ ²⁰⁸ One double-blind trial in women found that 135 mg per day of zinc for two weeks improved one measure of muscle strength.²⁰⁹ Whether these women were zinc deficient was not determined in this study. A double-blind study of male athletes with low blood levels of zinc found that 20 mg per day of zinc improved the flexibility of the red blood cells during exercise, which could benefit blood flow to the muscles.²¹⁰ No other studies of the effects of zinc supplementation in exercising people have been done. A safe amount of zinc for long-term use is 20 to 40 mg per day along with 1 to 2 mg of copper. Higher amounts should be taken only under the supervision of a doctor.

Alpha-ketoglutarate
Alpha-ketoglutarate (AKG) is used by cells during growth and in healing from injuries and other wounds,²¹¹ and is especially important in the healing of muscle tissue.²¹² A controlled study found that intravenous AKG prevented a decline in protein synthesis in the muscles of patients recovering from surgery.²¹³ ²¹⁴ For these reasons, it has been speculated that oral AKG supplements might help improve strength or muscle-mass gains by weight lifters, but no research has been done to test this theory.

Arginine/Ornithine
At very high intakes (approximately 250 mg per 2.2 pounds of body weight), the amino acid arginine has increased growth hormone levels,²¹⁵ an effect that has interested body builders due to the role of growth hormone in stimulating muscle growth.²¹⁶ However, at lower amounts recommended by some manufacturers (5 grams taken 30 minutes before exercise), arginine failed to increase growth hormone release and may even have impaired the release of growth hormone in younger adults.²¹⁷ Large quantities (170 mg per 2.2 pounds of body weight per day) of a related amino acid, ornithine, have also raised growth hormone levels in some athletes.²¹⁸ High amounts of arginine or ornithine do not appear to raise levels of insulin,²¹⁹ ²²⁰ another anabolic (bodybuilding) hormone. More modest amounts of a combination of these amino acids have not had measurable effects on any anabolic hormone levels during exercise.²²¹ ²²²

Nonetheless, double-blind trials conducted by one group of researchers, combining weight training with either arginine and ornithine (500 mg of each, twice per day, five times per week) or placebo, found the amino-acid combination produced decreases in body fat,²²³ resulted in higher total strength and lean body mass, and reduced evidence of tissue breakdown after only five weeks.²²⁴

Aspartic acid
Aspartic acid is a non-essential amino acid that participates in many biochemical reactions relating to energy and protein. Preliminary, though conflicting, animal and human research suggested a role for aspartic acid (in the form of potassium and magnesium aspartate) in reducing fatigue during exercise.²²⁵ However, most studies have found aspartic acid useless in improving either athletic performance or the body’s response to exercise.²²⁶ ²²⁷ ²²⁸ ²²⁹ ²³⁰

B-complex vitamins
The B-complex vitamins are important for athletes, because they are needed to produce energy from carbohydrates. Exercisers may have slightly increased requirements for some of the B vitamins, including vitamin B2, vitamin B6, and vitamin B5 (pantothenic acid);²³¹ athletic performance can suffer if these slightly increased needs are not met.²³² However, most athletes obtain enough B vitamins from their diet without supplementation,²³³ and supplementation studies have found no positive effect on performance measures for vitamin B2,²³⁴ ²³⁵ vitamin B3 (niacin),²³⁶ or vitamin B6.²³⁷ On the contrary, large amounts of niacin have been shown to impair endurance performance.²³⁸

Beta-sitosterol
Beta-sitosterol, (BSS) a natural sterol found in many plants, has been shown in a double-blind trial to improve immune function in marathon runners when combined with a related substance called B-sitosterol glucoside (BSSG).²³⁹ This implies that beta-sitosterol might reduce infections in athletes who engage in intensive exercise, though studies are still needed to prove this. The usual amount of this combination used in research is 20 mg of BSS and 200 mcg of BSSG three times per day.

Branched-chain amino acids
Some research has shown that supplemental branched-chain amino acids (BCAA) (typically 10 to 20 grams per day) do not result in meaningful changes in body composition,²⁴⁰ nor do they improve exercise performance or enhance the effects of physical training.²⁴¹ ²⁴² ²⁴³ ²⁴⁴ ²⁴⁵ ²⁴⁶ However, BCAA supplementation may be useful in special situations, such as preventing muscle loss at high altitudes and prolonging endurance performance in the heat.²⁴⁷ ²⁴⁸ One controlled study gave triathletes 6 grams per day of BCAA for one month before a competition, then 3 grams per day from the day of competition until a week following. Compared with a placebo, BCAA restored depleted glutamine stores and immune factors that occur in elite athletes, and led to a reported one-third fewer symptoms of infection during the period of supplementation.²⁴⁹ Studies by one group of researchers suggest that BCAA supplementation may also improve exercise-induced declines in some aspects of mental functioning.²⁵⁰ ²⁵¹ ²⁵²

Bromelain
Bromelain is effective for shortening the healing time of such injuries as sprains and strains.²⁵³ Typically, two to four tablets or capsules are taken several times per day. Other uses of bromelain for sports and fitness have not been studied.

Caffeine
Caffeine is present in many popular beverages and appears to have an effect on fat utilization.²⁵⁴ Caffeine does not benefit short-term, high-intensity exercise, according to most,²⁵⁵ ²⁵⁶ but not all, studies.²⁵⁷ ²⁵⁸ However, controlled research, much of it double-blind, has shown that endurance performance lasting at least 30 minutes does appear to be enhanced by caffeine in many athletes.²⁵⁹ ²⁶⁰ ²⁶¹ ²⁶² ²⁶³ Inconsistency in reported effectiveness of caffeine in some trials can be explained by differences in caffeine sensitivity among athletes, variable effects of caffeine on different forms of exercise and under different environmental conditions, and effects of other dietary components on the response to caffeine.²⁶⁴ ²⁶⁵ Effective amounts of caffeine appear to range from 1.4 to 2.7 mg per pound of body weight, taken one hour before exercise.²⁶⁶ While this amount of caffeine could be obtained in 1 to 3 cups of brewed coffee, most research has used caffeine supplements in capsules, and a recent study found caffeine was not effective when taken as coffee.²⁶⁷ Caffeine consumption is banned by the International Olympic Committee at levels that produce urinary concentrations of 12 mg per milliliter or more. These levels would require ingestion of considerably more than 2.5 mg per pound of body weight, or several cups of coffee, over a short period of time.²⁶⁸

Calcium
Calcium is important for achieving and maintaining optimum bone density. Some athletes, especially women with low body weight and/or amenorrhoea, are at risk for serious bone loss and fractures.²⁶⁹ ²⁷⁰ Contributing to this risk are the diets of these athletes, which are frequently deficient in calcium.²⁷¹ All athletes should try to achieve the recommended intakes of calcium, which are 1,300 mg per day for teenagers and 1,000 mg per day for adults. Other uses of calcium for sports and fitness, including prevention or relief of sports-related muscle cramps, have not been studied.

Chromium
Chromium, primarily in a form called chromium picolinate, has been studied for its potential role in altering body composition. Preliminary research in animals and humans suggested that chromium picolinate might increase fat loss and lean muscle tissue gain when used with a weight-training programme.²⁷² ²⁷³ ²⁷⁴ However, most studies have found little to no effect of chromium on body composition or strength.²⁷⁵ ²⁷⁶ ²⁷⁷ ²⁷⁸ ²⁷⁹ One group of researchers has reported significant reductions in body fat in double-blind trials using 200 to 400 mcg per day of chromium for six to twelve weeks in middle-aged adults,²⁸⁰ ²⁸¹ but the methods used in these studies have been criticized.²⁸²

Chondroitin sulphate
Chondroitin sulphate, 800 to 1,200 mg per day, is effective for reducing joint pain caused by osteoarthritis.²⁸³ ²⁸⁴ Other uses of chondroitin sulphate for sports and fitness, including prevention of joint pain or treatment of sports injuries, have not been studied.

CLA
Conjugated linoleic acid (CLA) is a slightly altered form of the essential fatty acid linoleic acid. Animal research suggests an effect of CLA supplementation on reducing body fat.²⁸⁵ ²⁸⁶ Controlled human research has reported that 5.6 to 7.2 grams per day of CLA produces only non-significant gains in muscle size and strength in experienced and inexperienced weight-training men.²⁸⁷ ²⁸⁸ ²⁸⁹ A double-blind study of a group of trained men and women reported reduced body fat in the upper arm after 12 weeks of supplementation with 1.8 grams per day of CLA.²⁹⁰ Further research using more accurate techniques for measuring body composition is needed to confirm these findings.

Coenzyme Q10
Strenuous physical activity lowers blood levels of coenzyme Q10 (CoQ10).²⁹¹ However, the effects of CoQ10 on how the healthy body responds to exercise have been inconsistent, with several studies finding no improvement.²⁹² ²⁹³ ²⁹⁴ ²⁹⁵ A few studies, using at least four weeks of CoQ10 supplementation at 60 to 100 mg per day, have reported improvements in measures of work capacity ranging from 3 to 29% in sedentary people and from 4 to 32% in trained athletes.²⁹⁶ However, recent double-blind and/or placebo-controlled trials in trained athletes, using performance measures such as time to exhaustion and total performance, have found either no significant improvement or significantly poorer results in those taking CoQ10.²⁹⁷ ²⁹⁸ ²⁹⁹

Gamma oryzanol
Gamma oryzanol is a mixture of sterols and ferulic acid esters. Despite claims that gamma oryzanol or its components increase testosterone levels, stimulate the release of endorphins, and promote the growth of lean muscle tissue, research has provided little support for these claims and has also shown gamma-oryzanol to be poorly absorbed.³⁰⁰ A recent nine-week, double-blind trial of 500 mg per day of gamma-oryzanol in weight lifters found no benefit compared with placebo in strength performance gains or circulating anabolic hormones.³⁰¹ However, a small, double-blind trial using 30 mg per day of ferulic acid for eight weeks in trained weight lifters did find significantly more weight gain (though lean body mass was not measured) and increased strength in one of three measures compared with placebo.³⁰²

Glucosamine
Glucosamine sulphate, 1,500 mg per day, is effective for reducing joint pain caused by osteoarthritis according to most studies.³⁰³ ³⁰⁴ ³⁰⁵ Whether other forms of glucosamine, such as glucosamine hydrochloride, are as effective for joint pain as glucosamine sulphate is unclear at this time, but studies have found some benefits from the use of the hydrochloride form.³⁰⁶ ³⁰⁷ Other uses of glucosamine for sports and fitness, including prevention of joint pain or treatment of sports injuries, have not been studied.

L-carnitine
L-carnitine, which is normally manufactured by the human body, has been popular as a potential ergogenic aid (i.e., having the ability to increase work capacity), because of its role in the conversion of fat to energy.³⁰⁸ However, while some studies have found that L-carnitine improves certain measures of muscle physiology, research on the effects of 2 to 4 grams of L-carnitine per day on performance have produced inconsistent results.³⁰⁹ L-carnitine may be effective in certain intense exercise activities leading to exhaustion,³¹⁰ but recent studies have reported that L-carnitine supplementation does not benefit non-exhaustive or even marathon-level endurance exercise,³¹¹ ³¹² anaerobic performance,³¹³ or lean body mass in weight lifters.³¹⁴

Magnesium
Magnesium deficiency can reduce exercise performance and contribute to muscle cramps, but sub-optimal intake does not appear to be a problem among most groups of athletes.³¹⁵ ³¹⁶ Controlled trials suggest that magnesium supplementation might improve some aspects of physiology important to sports performance in some athletes,³¹⁷ ³¹⁸ but controlled and double-blind trials focusing on performance benefits of 212 to 500 mg per day of magnesium have been inconsistent.³¹⁹ ³²⁰ ³²¹ ³²² ³²³ ³²⁴ It is possible that magnesium supplementation benefits only those who are deficient or who are not highly trained athletes. ³²⁵ ³²⁶

Medium chain triglycerides
Medium chain triglycerides (MCT) contain a class of fatty acids found only in very small amounts in the diet; they are more rapidly absorbed and burned as energy than are other fats.³²⁷ For this reason, athletes have been interested in their use, especially during prolonged endurance exercise. However, no effect on carbohydrate sparing or endurance exercise performance has been shown with moderate amounts of MCT (30 to 45 grams over two to three hours).³²⁸ ³²⁹ Controlled trials using very large amounts of MCT (approximately 85 grams over two hours) have resulted in both increased and decreased performance,³³⁰ ³³¹ while a double-blind trial found that 60 grams per day of MCT for two weeks had no effect on endurance performance.³³² A controlled study found increased performance when MCTs were added to a 10% carbohydrate solution,³³³ but another study found no advantage of adding MCT,³³⁴ and a third trial actually reported decreased performance with this combination, probably due to gastrointestinal distress, in athletes using MCTs.³³⁵

Octacosanol
Wheat germ oil, which contains a waxy substance known as octacosanol, has been investigated as an ergogenic agent. Preliminary studies have suggested that octacosanol improves endurance, reaction time, and other measures of exercise capacity.³³⁶ In another preliminary trial, supplementation with 1 mg per day of octacosanol for eight weeks improved grip strength and visual reaction time, but it had no effect on chest strength, auditory reaction time, or endurance.³³⁷

Ornithine alpha-ketoglutarate
Ornithine alpha-ketoglutarate (OKG) is formed from the amino acids ornithine and glutamine and is believed to facilitate muscle growth by enhancing the body’s release of anabolic hormones. While this effect has been found in studies on hospitalised patients and elderly people,³³⁸ ³³⁹ no studies on muscle growth in athletes using OKG have been published.

Methoxyisoflavone
Methoxyisoflavone is a member of the family flavonoids (isoflavones). In a U.S. Patent, the developers of this substance claim, based on preliminary animal research, that it possesses anabolic (muscle-building and bone-building) effects without the side effects seen with either androgenic (male) hormones or oestrogenic (female) hormones.³⁴⁰ A preliminary controlled trial found that strength-training athletes who took 800 mg per day of methoxyisoflavone for eight weeks experienced a significantly greater reduction in percentage body fat than those who took a placebo.³⁴¹ Double-blind research is needed to confirm these findings. The U.S. patent also claims methoxyisoflavone reduces appetite and lowers blood cholesterol levels. Whether this claim is true has not yet been demonstrated in published scientific research.

Ribose
Ribose is a type of sugar used by the body to make the energy-containing substance adenosine triphosphate (ATP). Intense exercise depletes muscle cells of ATP as well as the ATP precursors made from ribose,³⁴² ³⁴³ though these deficits are typically replaced within minutes.³⁴⁴ Unpublished reports suggested that ribose supplementation might increase power during short, intense bouts of exercise.³⁴⁵ ³⁴⁶ However, in a double-blind study, exercisers took four grams of ribose four times per day during a six-day strength-training regimen, and no effects on muscle power or ATP recovery in exercised muscles were found.³⁴⁷ In two other controlled studies, either 10 grams of ribose per day for five days or 8 grams every 12 hours for 36 hours resulted in only minor improvements in some measures of performance during repetitive sprint cycling.³⁴⁸ ³⁴⁹

Are there any side effects or interactions?
Refer to the individual supplement for information about any side effects or interactions.

Herbs that may be helpful

Ginseng
Extensive but often poorly designed studies have been conducted on the use of Asian ginseng (Panax ginseng) to improve athletic performance.³⁵⁰ ³⁵¹ While some early controlled studies suggested there might be benefits, several recent double-blind trials have found no significant effects of Asian ginseng on endurance exercise.³⁵² ³⁵³ ³⁵⁴ In many studies, it is possible that ginseng was used in insufficient amounts or for an inadequate length of time; a more effective regimen for enhancing endurance performance may be 2 grams of powdered root per day or 200 to 400 mg per day of an extract standardised for 4% ginsenosides, taken for eight to twelve weeks.³⁵⁵ Short-term intense exercise has also not been helped by Asian ginseng according to double-blind trials,³⁵⁶ ³⁵⁷ but one controlled study reported increased pectoral and quadricep muscle strength in non-exercising men and women after taking 1 gram per day of Asian ginseng for six weeks.³⁵⁸ An extract of a related plant, American ginseng (Panax quinquefolius), was found ineffective at improving endurance exercise performance in untrained people after one week’s supplementation in a double-blind study.³⁵⁹

Eleuthero
Eleuthero (Eleutherococcus senticosus) supplementation may improve athletic performance, according to preliminary Russian research.³⁶⁰ Other studies have been inconclusive and two recent double-blind studies showed no beneficial effect on endurance performance in trained men.³⁶¹ ³⁶² ³⁶³ Eleuthero strengthens the immune system and thus might reduce the risk of post-exercise infection. Although some doctors suggest taking 1 to 4 ml (0.2 to 0.8 tsp) of fluid extract of eleuthero three times per day, evidence supporting the use of this herb to enhance athletic performance remains weak.

Rhodiola
In a double-blind trial, healthy volunteers received 200 mg of an extract of Rhodiola rosea (standardized to contain 3% rosavin plus 1% salidroside) or a placebo one hour prior to an endurance-exercise test. Compared with placebo, rhodiola significantly increased endurance, as measured by the time it took to become exhausted.³⁶⁴ However, after daily use of rhodiola for four weeks, the herb no longer enhanced short-term endurance. Consequently, if rhodiola is being considered as an exercise aid, it should be used only occasionally.

Arnica
Arnica-containing ointments are recommended by many practitioners for the treatment of sprains and strains and other traumatic injuries.³⁶⁵ Homoeopathic arnica tablets are also used by some practitioners for similar conditions.³⁶⁶ One uncontrolled trial showed that arnica gel applied twice daily reduced symptoms of osteoarthritis of the knee and a double-blind study reported that a combination of topical arnica ointment and oral homoeopathic arnica tablets reduced pain in people recovering from hand surgery.³⁶⁷ ³⁶⁸ No other studies of topical arnica have been done, but several studies of homoeopathic arnica have found it ineffective for treating muscle and joint pain.³⁶⁹ ³⁷⁰ ³⁷¹

Cayenne (topical capsaicin)
Capsaicin ointment, applied four times per day over painful joints in the upper or lower limbs, reduces pain caused by osteoarthritis,³⁷² and a plaster containing capsaicin applied to the low back for several hours per day provided relief from chronic low back pain in one study.³⁷³ Other uses of cayenne or capsaicin for sports and fitness have not been studied.

Eucalyptus
Eucalyptus-based rubs have been found to warm muscles in athletes.³⁷⁴ This suggests that eucalyptus may help relieve minor muscle soreness when applied topically, though studies are needed to confirm this possibility.

Guaraná and kola
Some athletes take guaraná during their training; however, there is no scientific research to support this use. Guaraná contains caffeine. Another caffeine-containing herb sometimes used during training is kola nut.

Tribulus
Extracts of Tribulus terrestris (puncture vine) have been reported in preliminary studies to affect anabolic hormones in men.³⁷⁵ However, a double-blind trial found no effect of 1.5 mg per day of tribulus per pound of body weight on improving body composition or strength performance results from an eight-week strength training programme.³⁷⁶

Yohimbine
The ability of yohimbine, a chemical found in yohimbe bark, to stimulate the nervous system,³⁷⁷ ³⁷⁸ promote the release of fat from fat cells,³⁷⁹ ³⁸⁰ and affect the cardiovascular system ³⁸¹ has led to claims that yohimbe might help athletic performance or improve body composition. However, a double-blind study of men who were not dieting reported no effect of up to 43 mg per day of yohimbine on weight or body composition after six months.³⁸² No research has tested yohimbe herb for effects on body composition, and no human research has investigated the ability of yohimbine or yohimbe to affect athletic performance. Other studies have determined that a safe daily amount of yohimbine is 15 to 30 mg.³⁸³ However, people with kidney disorders should not take yohimbe, and side effects of nausea, dizziness, or nervousness may occur that necessitate reducing or stopping yohimbe supplementation.

Are there any side effects or interactions?
Refer to the individual herb for information about any side effects or interactions.

References
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1. American Dietetic Association. Position of the American Dietetic Association and the Canadian Dietetic Association: Nutrition for physical fitness and athletic performance for adults. J Am Diet Assoc 1993;93:691–6.

2. Wilmore JH, Costill DL. Physiology of Sport and Exercise. Champaign, IL: Human Kinetics, 1994, 110–4.

3. Grandjean AC. Sports nutrition. In: Mellion MB, Walsh WM, Shelton GL, eds. The Team Physician’s Handbook. Philadelphia, PA: Hanley & Belfus, 1990,78–91.

4. Thornton JS. Feast or famine: eating disorders in athletes. Phys Sportsmed 1990;18:116–22 [review].

5. Thornton JS. How can you tell when an athlete is too thin? Phys Sportsmed 1990;18:124–33 [review].

6. Walberg-Rankin J. Dietary carbohydrate as an ergogenic aid for prolonged and brief competitions in sport. Int J Sport Nutr 1995;5:S13–38 [review].

7. Jacobs KA, Sherman WM. The efficacy of carbohydrate supplementation and chronic high-carbohydrate diets for improving endurance performance. Int J Sport Nutr 1999;9:92–115 [review].

8. Costill DL. Carbohydrates for exercise: dietary demands for optimal performance. Int J Sports Med 1988;9:1–18 [review].

9. Craig BW. The influence of fructose feeding on physical performance. Am J Clin Nutr 1993;58:815S–9S [review].

10. Walberg-Rankin J. Dietary carbohydrate as an ergogenic aid for prolonged and brief competitions in sport. Int J Sport Nutr 1995;5:S13–28 [review].

11. Ivy JL, Goforth HW Jr, Damon BM, et al. Early postexercise muscle glycogen recovery is enhanced with a carbohydrate-protein supplement. J Appl Physiol 2002;93:1337–44.

12. Ivy JL. Glycogen resynthesis after exercise: effect of carbohydrate intake. Int J Sports Med 1998;19:S142–5 [review].

13. Cade JR, Reese RH, Privette RM, et al. Dietary intervention and training in swimmers. Eur J Appl Physiol Occup Physiop 1991;63:210–5.

14. Jentjens RL, van Loon LJ, Mann CH, et al. Addition of protein and amino acids to carbohydrates does not enhance postexercise muscle glycogen synthesis. J Appl Physiol 2001;91:839–46.

15. Van Hall G, Shirreffs SM, Calbet JA. Muscle glycogen resynthesis during recovery from cycle exercise: no effect of additional protein ingestion. J Appl Physiol 2000;88:1631–6.

16. Carrithers JA, Williamson DL, Gallagher PM, et al. Effects of postexercise carbohydrate-protein feedings on muscle glycogen restoration. J Appl Physiol 2000;88:1976–82.

17. Van Loon LJ, Saris WH, Kruijshoop M, Wagenmakers AJ. Maximizing postexercise muscle glycogen synthesis: carbohydrate supplementation and the application of amino acid or protein hydrolysate mixtures. Am J Clin Nutr 2000;72:106–11.

18. Roy BD, Tarnopolsky MA. Influence of differing macronutrient intakes on muscle glycogen resynthesis after resistance exercise. J Appl Physiol 1998;84:890–6.

19. Gibala MJ. Dietary protein, amino acid supplements, and recovery from exercise. Sports Sci Exch 2002;15:1–4.

20. Hawley JA, Schabort EJ, Noakes TD, et al. Carbohydrate loading and exercise performance. An update. Sports Med 1997;24:73–81 [review].

21. Costill DL. Carbohydrates for exercise: dietary demands for optimal performance. Int J Sports Med 1988;9:1–18 [review].

22. Rankin JW. Glycemic index and exercise metabolism. Sports Sci Exch 1997;10:1–8 [review].

23. Thomas DE, Brotherhood JR, Brand JC. Carbohydrate feeding before exercise: effect of glycemic index. Int J Sports Med 1991;12:180–6.

24. DeMarco HM, Sucher KP, Cisar CJ, Butterfield GE. Pre-exercise carbohydrate meals: application of glycemic index. Med Sci Sports Exerc 1999;31:164–70.

25. Kirwan JP, Cyr-Campbell D, Campbell WW, et al. Effects of moderate and high glycemic index meals on metabolism and exercise performance. Metabolism 2001;50:849–55.

26. Kirwan JP, O'Gorman DJ, Cyr-Campbell D, et al. Effects of a moderate glycemic meal on exercise duration and substrate utilization. Med Sci Sports Exerc 2001;33:1517–23.

27. Febbraio MA, Keenan J, Angus DJ, et al. Preexercise carbohydrate ingestion, glucose kinetics, and muscle glycogen use: effect of the glycemic index. J Appl Physiol 2000;89:1845–51.

28. Stannard SR, Constantini NW, Miller JC. The effect of glycemic index on plasma glucose and lactate levels during incremental exercise. Int J Sport Nutr Exerc Metab 2000;10:51–61.

29. Wee SL, Williams C, Gray S, Horabin J. Influence of high and low glycemic index meals on endurance running capacity. Med Sci Sports Exerc 1999;31:393–9.

30. Sparks MJ, Selig SS, Febbraio MA. Pre-exercise carbohydrate ingestion: effect of the glycemic index on endurance exercise performance. Med Sci Sports Exerc 1998;30:844–9.

31. Thomas DE, Brotherhood JR, Miller JB. Plasma glucose levels after prolonged strenuous exercise correlate inversely with glycemic response to food consumed before exercise. Int J Sport Nutr 1994;4:361–73.

32. Goodpaster BH, Costill DL, Fink WJ, et al. The effects of pre-exercise starch ingestion on endurance performance. Int J Sports Med 1996;17:366–72.

33. Craig BW. The influence of fructose feeding on physical performance. Am J Clin Nutr 1993;58:815S–9S [review].

34. Burke LM, Collier GR, Hargreaves M. Glycemic index—a new tool in sport nutrition? Int J Sport Nutr 1998;8:401–15 [review].

35. Lemon PW. Effects ofexercise on dietary protein requirements. Int J Sport Nutr 1998;8:426–47 [review].

36. Lemon PW. Is increased dietary protein necessary or beneficial for individuals with a physically active lifestyle? Nutr Rev 1996;54:S169–75 [review].

37. Poortmans JR, Dellalieux O. Do regular high protein diets have potential health risks on kidney function in athletes? Int J Sport Nutr Exerc Metab 2000;10:28–38.

38. Miller SL, Tipton KD, Chinkes DL, et al. Independent and combined effects of amino acids and glucose after resistance exercise. Med Sci Sports Exerc 2003;35:449–55.

39. Tipton KD, Borsheim E, Wolf SE, et al. Acute response of net muscle protein balance reflects 24-h balance after exercise and amino acid ingestion. Am J Physiol Endocrinol Metab 2003;284:E76–89.

40. Borsheim E, Tipton KD, Wolf SE, Wolfe RR. Essential amino acids and muscle protein recovery from resistance exercise. Am J Physiol Endocrinol Metab 2002;283:E648–57.

41. Levenhagen DK, Gresham JD, Carlson MG, et al. Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and protein homeostasis. Am J Physiol Endocrinol Metab 2001;280:E982–3.

42. Kraemer WJ, Volek JS, Bush JA, et al. Hormonal responses to consecutive days of heavy-resistance exercise with or without nutritional supplementation. J Appl Physiol 1998;85:1544–55.

43. Chandler RM, Byrne HK, Patterson JG, Ivy JL. Dietary supplements affect the anabolic hormones after weight-training exercise. J Appl Physiol 1994;76:839–45.

44. Tipton KD, Rasmussen BB, Miller SL, et al. Timing of amino acid-carbohydrate ingestion alters anabolic response of muscle to resistance exercise. Am J Physiol Endocrinol Metab 2001;281:E197–206.

45. Rozenek R, Ward P, Long S, Garhammer J. Effects of high-calorie supplements on body composition and muscular strength following resistance training. J Sports Med Phys Fitness 2002;42:340–7.

46. Williams AG, van den Oord M, Sharma A, Jones DA. Is glucose/amino acid supplementation after exercise an aid to strength training? Br J Sports Med 2001;35:109–13.

47. Lemon PW, Tarnopolsky MA, MacDougall JD, Atkinson SA. Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. J Appl Physiol 1992;73:767–75.

48. Sherman WM, Leenders N. Fat loading: the next magic bullet? Int J Sport Nutr 1995;5:S1–12 [review].

49. Helge JW. Long-term fat diet adaptation effects on performance, training capacity, and fat utilization. Med Sci Sports Exerc 2002;34:1499–504 [review].

50. Burke LM, Hawley JA. Effects of short-term fat adaptation on metabolism and performance of prolonged exercise. Med Sci Sports Exerc 2002;34:1492–8 [review].

51. Hawley JA, Brouns F, Jeukendrup A. Strategies to enhance fat utilisation during exercise. Sports Med 1998;25:241–57 [review].

52. Hawley JA, Hopkins WG. Aerobic glycolytic and aerobic lipolytic power systems. A new paradigm with implications for endurance and ultraendurance events. Sports Med 1995;19:240–50 [review].

53. Carey AL, Staudacher HM, Cummings NK, et al. Effects of fat adaptation and carbohydrate restoration on prolonged endurance exercise. J Appl Physiol 2001;91:115–22.

54. Burke LM, Angus DJ, Cox GR, et al. Effect of fat adaptation and carbohydrate restoration on metabolism and performance during prolonged cycling. J Appl Physiol 2000;89:2413–21.

55. Burke LM, Hawley JA, Angus DJ, et al. Adaptations to short-term high-fat diet persist during exercise despite high carbohydrate availability. Med Sci Sports Exerc 2002;34:83–91.

56. Lambert EV, Goedecke JH, Zyle C, et al. High-fat diet versus habitual diet prior to carbohydrate loading: effects of exercise metabolism and cycling performance. Int J Sport Nutr Exerc Metab 2001;11:209–25.

57. Pivarnik JM, Palmer JM. Water and electrolyte balance during rest and exercise. In: Wolinsky I, Hickson JF, eds. Nutrition in Exercise and Sport, 2nd ed. Boca Raton, FL: CRC Press, 1994, 245–63 [review].

58. Convertino VA, Armstrong LE, Coyle EF, et al. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc 1996;28:i–vii [review].

59. Passe DH, Horn M, Murray R. Impact of beverage acceptability on fluid intake during exercise. Appetite 2000;35:219–29.

60. McArdle WD, Katch FI, Katch VL. Chapter 12, Body composition assessment and sport-specific observations. In: Sports & Exercise Nutrition. Philadelphia, PA: Lippincott, Williams & Wilkins, 1999.

61. Campbell B, Baer J, Roberts M, et al. Effects of arginine alpha-ketoglutarate supplementation on body composition and training adaptations. Sports Nutrition Review Journal 2004:1(1):S10 [abstract].

62. Greenhaff PL, Bodin K, Soderlund K, et al. Effect of oral creatine supplementation on skeletal muscle phosphocreatine resynthesis. Am J Physiol 1994;266:E725–30.

63. Greenhaff PL. Creatine and its application as an ergogenic aid. Int J Sport Nutr 1995;5:94–101.

64. Harris RC, Soderlund K, Hultman E. Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clin Sci 1992;83:367–74.

65. Green AL, Simpson EJ, Littlewood JJ, et al. Carbohydrate ingestion augments creatine retention during creatine feeding in humans. Acta Physiol Scand 1996;158:195–202.

66. Kreider RB, Ferreira M, Wilson M, et al. Effects of creatine supplementation on body composition, strength, and sprint performance. Med Sci Sports Exerc 1998;30:73–82.

67. Mesa JL, Ruiz JR, Gonzalez-Gross MM, et al. Oral creatine supplementation and skeletal muscle metabolism in physical exercise. Sports Med 2002;32:903–44 [review].

68. Watsford ML, Murphy AJ, Spinks WL, Walshe AD. Creatine supplementation and its effect on musculotendinous stiffness and performance. J Strength Cond Res 2003;17:26–33.

69. van Loon LJ, Oosterlaar AM, Hartgens F. Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans. Clin Sci (Lond) 2003;104:153–62.

70. Warber JP, Tharion WJ, Patton JF, et al. The effect of creatine monohydrate supplementation on obstacle course and multiple bench press performance. J Strength Cond Res 2002;16:500–8.

71. Ziegenfuss TN, Rogers M, Lowery L, et al. Effect of creatine loading on anaerobic performance and skeletal muscle volume in NCAA Division I athletes. Nutrition 2002;18:397–402.

72. Cottrell GT, Coast JR, Herb RA. Effect of recovery interval on multiple-bout sprint cycling performance after acute creatine supplementation. J Strength Cond Res 2002;16:109–16.

73. Izquierdo M, Ibanez J, Gonzalez-Badillo JJ, Gorostiaga EM. Effects of creatine supplementation on muscle power, endurance, and sprint performance. Med Sci Sports Exerc 2002;34:332–43.

74. Mesa JL, Ruiz JR, Gonzalez-Gross MM, et al. Oral creatine supplementation and skeletal muscle metabolism in physical exercise. Sports Med 2002;32:903–44 [review].

75. Mesa JL, Ruiz JR, Gonzalez-Gross MM, et al. Oral creatine supplementation and skeletal muscle metabolism in physical exercise. Sports Med 2002;32:903–44 [review].

76. Warber JP, Tharion WJ, Patton JF, et al. The effect of creatine monohydrate supplementation on obstacle course and multiple bench press performance. J Strength Cond Res 2002;16:500–8.

77. Mesa JL, Ruiz JR, Gonzalez-Gross MM, et al. Oral creatine supplementation and skeletal muscle metabolism in physical exercise. Sports Med 2002;32:903–44 [review].

78. Van Loon LJ, Oosterlaar AM, Hartgens F. Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans. Clin Sci (Lond) 2003;104:153–62.

79. Izquierdo M, Ibanez J, Gonzalez-Badillo JJ, Gorostiaga EM. Effects of creatine supplementation on muscle power, endurance, and sprint performance. Med Sci Sports Exerc 2002;34:332–43.

80. Van Loon LJ, Oosterlaar AM, Hartgens F. Effects of creatine loading and prolonged creatine supplementation on body composition, fuel selection, sprint and endurance performance in humans. Clin Sci (Lond) 2003;104:153–62.

81. Vandenberghe K, Goris M, Van Hecke P, et al. Long-term creatine intake is beneficial to muscle performance during resistance training. J Appl Physiol 1997;83:2055–63.

82. Becque MD, Lochmann JD, Melrose DR. Effects of oral creatine supplementation on muscular strength and body composition. Med Sci Sports Exerc 2000;32:654–8.

83. Brose A, Parise G, Tarnopolsky MA. Creatine supplementation enhances isometric strength and body composition improvements following strength exercise training in older adults. J Gerontol A Biol Sci Med Sci 2003;58:11–9.

84. Chrusch MJ, Chilibeck PD, Chad KE Creatine supplementation combined with resistance training in older men. Med Sci Sports Exerc 2001;33:2111–7.

85. Stout JR, Eckerson J, Noonan D, et al. The effects of a supplement designed to augment creatine uptake on exercise performance and fat-free mass in football players. Med Sci Sports Exerc 1997;29:S251 [abstract].

86. Wilder N, Gilders R, Hagerman F, Deivert RG. The effects of a 10-week, periodized, off-season resistance-training program and creatine supplementation among collegiate football players. J Strength Cond Res 2002;16:343–52.

87. Kreider RB, Ferreira M, Wilson M, et al. Effects of creatine supplementation on body composition, strength, and sprint performance. Med Sci Sports Exerc 1998;30:73–82.

88. Mesa JL, Ruiz JR, Gonzalez-Gross MM, et al. Oral creatine supplementation and skeletal muscle metabolism in physical exercise. Sports Med 2002;32:903–44 [review].

89. Volek JS, Duncan ND, Mazzetti SA, et al. Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training. Med Sci Sports Exerc 1999;31:1147–56.

90. Becque MD, Lochmann JD, Melrose DR. Effects of oral creatine supplementation on muscular strength and body composition. Med Sci Sports Exerc 2000;32:654–8.

91. Willoughby DS, Rosene J. Effects of oral creatine and resistance training on myosin heavy chain expression. Med Sci Sports Exerc 2001;33:1674–81.

92. Short SH. Surveys of dietary intake and nutrition knowledge of athletes and their coaches. In: Wolinsky I, Hickson JF, eds. Nutrition in Exercise and Sport, 2nd ed. Boca Raton, FL: CRC Press, 1994, 367–416.

93. Clarkson PM, Haymes EM. Exercise and mineral status of athletes: calcium, magnesium, phosphorus, and iron. Med Sci Sports Exerc 1995 Jun;27(6):831–43 [review].

94. Lukaski HC. Micronutrients (magnesium, zinc, and copper): are mineral supplements needed for athletes? Int J Sport Nutr 1995;5:S74–83 [review].

95. Van der Beek EJ. Vitamin supplementation and physical exercise performance. J Sports Sci 1991;9:77–90 [review].

96. McDonald R, Keen CL. Iron, zinc and magnesium nutrition and athletic performance. Sports Med 1988;5:171–84 [review].

97. Telford RD, Catchpole EA, Deakin V, et al. The effect of 7 to 8 months of vitamin/mineral supplementation on athletic performance. Int J Sport Nutr 1992;2:135–53.

98. Singh A, Moses FM, Deuster PA. Chronic multivitamin-mineral supplementation does not enhance physical performance. Med Sci Sports Exerc 1992;24:726–32.

99. Weight LM, Myburgh KH, Noakes TD. Vitamin and mineral supplementation: effect on the running performance of trained athletes. Am J Clin Nutr 1988;47:192–5.

100. Margaritis I, Tessier F, Prou E, et al. Effects of endurance training on skeletal muscle oxidative capacities with and without selenium supplementation. J Trace Elem Med Biol 1997;11:37–43.

101. Fawcett JP, Farquhar SJ, Walker RJ, et al. The effect of oral vanadyl sulfate on body composition and performance in weight-training athletes. Int J Sport Nutr 1996;6:382–90.

102. Kanter M. Free radicals, exercise and antioxidant supplementation. Proc Nutr Soc 1998;57:9–13 [review].

103. Dekkers JC, Van Doornen LJ, Kemper HC. The role of antioxidant vitamins and enzymes in the prevention of exercise-induced muscle damage. Sports Med 1996;21(3):213–38 [review].

104. Jakeman P, Maxwell S. Effect of antioxidant vitamin supplementation on muscle function after eccentric exercise. Eur J Appl Physiol 1993;67:426–30.

105. Kaminski M, Boal R. An effect of ascorbic acid on delayed-onset muscle soreness. Pain 1992;50:317–21.

106. Thompson D, Williams C, McGregor SJ, et al. Prolonged vitamin C supplementation and recovery from demanding exercise. Int J Sport Nutr Exerc Metab 2001;11:466–81.

107. Thompson D, Williams C, Garcia-Roves P, et al. Post-exercise vitamin C supplementation and recovery from demanding exercise. Eur J Appl Physiol 2003;89:393–400.

108. Itoh H, Ohkuwa T, Yamazaki Y, et al. Vitamin E supplementation attenuates leakage of enzymes following 6 successive days of running training. Int J Sports Med 2000;21:369–74.

109. McBride JM, Kraemer WJ, Triplett-McBride T, Sebastianelli W. Effect of resistance exercise on free radical production. Med Sci Sports Exerc 1998;30:67–72.

110. Evans WJ. Vitamin E, vitamin C, and exercise. Am J Clin Nutr 2000;72:647S–52S [review].

111. Dawson B, Henry GJ, Goodman C, et al. Effect of Vitamin C and E supplementation on biochemical and ultrastructural indices of muscle damage after a 21 km run. Int J Sports Med 2002;23:10–15.

112. Beaton LJ, Allan DA, Tarnopolsky MA, et al. Contraction-induced muscle damage is unaffected by vitamin E supplementation. Med Sci Sports Exerc 2002;34:798–805.

113. Petersen EW, Ostrowski K, Ibfelt T, et al. Effect of vitamin supplementation on cytokine response and on muscle damage after strenuous exercise. Am J Physiol Cell Physiol 2001;280:C1570–5.

114. Kanter MM, Nolte LA, Holloszy JO. Effects of an antioxidant vitamin mixture on lipid peroxidation at rest and postexercise. J Appl Physiol 1993;74:965–9.

115. Kaikkonen J, Kosonen L, Nyyssonen K, et al. Effect of combined coenzyme Q10 and d-alpha-tocopheryl acetate supplementaion on exercise-induced lipid peroxidation and muscular damage: a placebo-controlled double-blind study in marathon runners. Free Radic Res 1998;29:85–92.

116. Singh A, Failla ML, Deuster PA. Exercise-induced changes in immune function: effects of zinc supplementation. J Appl Physiol 1994;76:2298–303.

117. Johnston CS, Swan PD, Corte C. Substrate utilization and work efficiency during submaximal exercise in vitamin C depleted-repleted adults. Int J Vitam Nutr Res 1999;69:41–4.

118. Gerster H. The role of vitamin C in athletic performance. J Am Coll Nutr 1989;8:636–43 [review].

119. Tiidus PM, Houston ME. Vitamin E status and response to exercise training. Sports Med 1995;20:12–23 [review].

120. Akova B, Surmen-Gur E, Gur H, et al. Exercise-induced oxidative stress and muscle performance in healthy women: role of vitamin E supplementation and endogenous oestradiol. Eur J Appl Physiol 2001;84:141–7.

121. Simon-Schnass I, Pabst H. Influence of vitamin E on physical performance. Int J Vitam Nutr Res 1988;58:49–54.

122. Shepard RJ. Vitamin E and athletic performance. J Sports Med 1983;23:461–70 [review].

123. Horswill CA. Effects of bicarbonate, citrate, and phosphate loading on performance. Int J Sport Nutr 1995;5:S111–9 [review].

124. Linderman JK, Gosselink KL. The effects of sodium bicarbonate ingestion on exercise performance. Sports Med 1994;18:75–80 [review].

125. Stephens TJ, McKenna MJ, Canny BJ, et al. Effect of sodium bicarbonate on muscle metabolism during intense endurance cycling. Med Sci Sports Exerc 2002;34:614–21.

126. Shave R, Whyte G, Siemann A, Doggart L. The effects of sodium citrate ingestion on 3,000-meter time-trial performance. J Strength Cond Res 2001;15:230–4.

127. Schabort EJ, Wilson G, Noakes TD. Dose-related elevations in venous pH with citrate ingestion do not alter 40-km cycling time-trial performance. Eur J Appl Physiol 2000;83:320–7.

128. McNaughton L, Dalton B, Palmer G. Sodium bicarbonate can be used as an ergogenic aid in high-intensity, competitive cycle ergometry of 1 h duration. Eur J Appl Physiol Occup Physiol 1999;80:64–9.

129. Potteiger JA, Webster MJ, Nickel GL, et al. The effects of buffer ingestion on metabolic factors related to distance running performance. Eur J Appl Physiol Occup Physiol 1996;72:365–71.

130. Potteiger JA, Nickel GL, Webster MJ, et al. Sodium citrate ingestion enhances 30 km cycling performance. Int J Sports Med 1996;17:7–11.

131. Tiryaki GR, Atterbom HA. The effects of sodium bicarbonate and sodium citrate on 600 m running time of trained females. J Sports Med Phys Fitness 1995;35:194–8.

132. Horswill CA. Effects of bicarbonate, citrate, and phosphate loading on performance. Int J Sport Nutr 1995;5:S111–9 [review].

133. Van Someren K, Fulcher K, McCarthy J, et al. An investigation into the effects of sodium citrate ingestion on high-intensity exercise performance. Int J Sport Nutr 1998;8:356–63.

134. Cox G, Jenkins DG. The physiological and ventilatory responses to repeated 60 s sprints following sodium citrate ingestion. J Sports Sci 1994;12:469–75.

135. McNaughton L, Cedaro R. Sodium citrate ingestion and its effects on maximal anaerobic exercise of different durations. Eur J Appl Physiol 1992;64:36–41.

136. Potteiger JA, Webster MJ, Nickel GL, et al. The effects of buffer ingestion on metabolic factors related to distance running performance. Eur J Appl Physiol 1996;72:365–71.

137. Tiryaki GR, Atterbom HA. The effects of sodium bicarbonate and sodium citrate on 600 m running time of trained females. J Sports Med Phys Fitness 1995;35:194–8.

138. McNaughton LR. Sodium citrate and anaerobic performance: implications of dosage. Eur J Appl Physiol 1990;61:392–7.

139. Galloway SD, Tremblay MS, Sexsmith JR, et al. The effects of acute phosphate supplementation in subjects of different aerobic fitness levels. Eur J Appl Physiol 1996;72:224–30.

140. Williams MH. Ergogenic and ergolytic substances. Med Sci Sports Exer 1992;24:S344–8 [review].

141. Morales AJ, Haubrich RH, Hwang JY, et al. The effect of six months treatment with a 100 mg daily dose of dehydroepiandrosterone (DHEA) on circulating sex steroids, body composition and muscle strength in age-advanced men and women. Clin Endocrinol (Oxf) 1998;49:421–32.

142. Percheron G, Hogrel JY, Denot-Ledunois S, et al. Effect of 1-year oral administration of dehydroepi sterone to 60- to 80-year-old individuals on muscle function and cross-sectional area: a double-blind placebo-controlled trial. Arch Intern Med 2003;163:720–7.

143. Wallace MB, Lim J, Cutler A, Bucci L. Effects of dehydroepiandrosterone vs androstenedione supplementation in men. Med Sci Sports Exerc 1999;31:1788–92.

144. Brown GA, Vukovich MD, Sharp RL. Effect of oral DHEA on serum testosterone and adaptations to resistance training in young men. J Appl Physiol 1999;87:2274–83.

145. Pivarnik JM, Palmer JM. Water and electrolyte balance during rest and exercise. In: Wolinsky I, Hickson JF, eds. Nutrition in Exercise and Sport, 2nd ed. Boca Raton, FL: CRC Press, 1994:245–63 [review].

146. Convertino VA, Armstrong LE, Coyle EF, et al. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc 1996;28(1):i–vii [review].

147. Convertino VA, Armstrong LE, Coyle EF, et al. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc 1996;28(1):i–vii [review].

148. Vrijens DM, Rehrer NJ. Sodium-free fluid ingestion decreases plasma sodium during exercise in the heat. J Appl Physiol 1999;86:1847–51.

149. Antonio J, Street C. Glutamine: a potentially useful supplement for athletes. Can J Appl Physiol 1999;24:1–14 [review].

150. Rowbottom DG, Keast D, Morton AR. The emerging role of glutamine as an indicator of exercise stress and overtraining. Sports Med 1996;21:80–97 [review].

151. Welbourne TC. Increased plasma bicarbonate and growth hormone after an oral glutamine load. Am J Clin Nutr 1995;61:1058–61.

152. Macintyre JG. Growth hormone and athletes. Sports Med 1987;4:129–42 [review].

153. Varnier M, Leese GP, Thompson J, et al. Stimulatory effect of glutamine on glycogen accumulation in human skeletal muscle. Am J Physiol 1995;269:E309–15.

154. Antonio J, Sanders MS, Kalman D, et al. The effects of high-dose glutamine ingestion on weightlifting performance. J Strength Cond Res 2002;16:157–60.

155. Haub MD, Potteiger JA, Nau KL, et al. Acute L-glutamine ingestion does not improve maximal effort exercise. J Sports Med Phys Fitness 1998;38:240–4.

156. Rohde T, MacLean DA, Pedersen BK. Effect of glutamine supplementation on changes in the immune system induced by repeated exercise. Med Sci Sports Exerc 1998;30:856–62.

157. Castell LM, Newsholme EA. Glutamine and the effects of exhaustive exercise upon the immune response. Can J Physiol Pharmacol 1998;76:524–32 [review].

158. Castell LM, Poortmans JR, Newsholme EA. Does glutamine have a role in reducing infections in athletes? Eur J Appl Physiol 1996;73:488–90.

159. Kingsley MI, Miller M, Kilduff LP, et al. Effects of phosphatidylserine on exercise capacity during cycling in active males. Med Sci Sports Exerc 2006;38:64–71.

160. Ransone J, Neighbors K, Lefavi R, Chromiak J. The effect of beta-hydroxy beta-methylbutyrate on muscular strength and body composition in collegiate football players. J Strength Cond Res 2003;17:34–9.

161. Kreider R, Ferreira M, Wilson M, et al. Effects of calcium beta-HMB supplementation with or without creatine during training on body composition alterations. FASEB J 1997;11:A374 [abstract].

162. Slater G, Jenkins D, Logan P, et al. Beta-hydroxy-beta-methylbutyrate (HMB) supplementation does not affect changes in strength or body composition during resistance training in trained men. Int J Sport Nutr Exerc Metab 2001;11:384–96.

163. Kreider RB, Ferreira M, Wilson M, Almada AL. Effects of calcium beta-hydroxy-beta-methylbutyrate (HMB) supplementation during resistance-training on markers of catabolism, body composition and strength. Int J Sports Med 1999;20:503–9.

164. Slater GJ, Jenkins D. Beta-hydroxy-beta-methylbutyrate (HMB) supplementation and the promotion of muscle growth and strength. Sports Med 2000;30:105–16 [review].

165. Vukovich MD, Stubbs NB, Bohlken RM. Body composition in 70-year-old adults responds to dietary beta-hydroxy-beta-methylbutyrate similarly to that of young adults. J Nutr 2001;131:2049–52.

166. Gallagher PM, Carrithers JA, Godard MP, et al. Beta-hydroxy-beta-methylbutyrate ingestion, Part I: effects on strength and fat free mass. Med Sci Sports Exerc 2000;32:2109–15.

167. Bucci LR. Nutrients as ergogenic aids for sports and exercise. Boca Raton, FL: CRC Press, 1993, 61–2 [review].

168. Williams MH, Kreider RB, Hunter DW, et al. Effect of inosine supplementation on 3-mile treadmill run performances and VO2 peak. Med Sci Sports Exerc 1990;22:517–22.

169. Starling RD, Trappe TA, Short KR, et al. Effect of inosine supplementation on aerobic and anaerobic cycling performance. Med Sci Sports Exerc 1996;28:1193–8.

170. McNaughton L, Dalton B, Tarr J. Inosine supplementation has no effect on aerobic or anaerobic cycling performance. Int J Sport Nutr 1999;9:333–44.

171. Mechrefe A, Wexler B, Feller E. Sports anemia and gastrointestinal bleeding in endurance athletes. Med Health R I 1997;80:216–8.

172. Clarkson PM. Micronutrients and exercise: anti-oxidants and minerals. J Sports Sci 1995;13:S11–24 [review].

173. Smith JA. Exercise, training and red blood cell turnover. Sports Med 1995;19:9–31.

174. Smith JA. Exercise, training and red blood cell turnover. Sports Med 1995;19:9–31 [review].

175. Brownlie T 4th, Utermohlen V, Hinton PS, et al. Marginal iron deficiency without anemia impairs aerobic adaptation among previously untrained women. Am J Clin Nutr 2002;75:734–42.

176. Friedmann B, Weller E, Mairbaurl H, Bartsch P. Effects of iron repletion on blood volume and performance capacity in young athletes. Med Sci Sports Exerc 2001;33:741–6.

177. Hinton PS, Giordano C, Brownlie T, Haas JD. Iron supplementation improves endurance after training in iron-depleted, nonanemic women. J Appl Physiol 2000;88:1103–11.

178. Zhu YI, Haas JD. Altered metabolic response of iron-depleted nonanemic women during a 15-km time trial. J Appl Physiol 1998;84:1768–75.

179. Nielsen P, Nachtigall D. Iron supplementation in athletes. Current recommendations. Sports Med 1998;26:207–16 [review].

180. Brutsaert TD, Hernandez-Cordero S, Rivera J, et al. Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic women. Am J Clin Nutr 2003;77:441–8.

181. Tipton KD, Ferrando AA, Phillips SM, et al. Postexercise net protein synthesis in human muscle from orally administered amino acids. Am J Physiol 1999;276:E628–34.

182. Miller SL, Tipton KD, Chinkes DL, et al. Independent and combined effects of amino acids and glucose after resistance exercise. Med Sci Sports Exerc 2003;35:449–55.

183. Tipton KD, Borsheim E, Wolf SE, et al. Acute response of net muscle protein balance reflects 24-h balance after exercise and amino acid ingestion. Am J Physiol Endocrinol Metab 2003;284:E76–89.

184. Borsheim E, Tipton KD, Wolf SE, Wolfe RR. Essential amino acids and muscle protein recovery from resistance exercise. Am J Physiol Endocrinol Metab 2002;283:E648–57.

185. Levenhagen DK, Gresham JD, Carlson MG, et al. Postexercise nutrient intake timing in humans is critical to recovery of leg glucose and protein homeostasis. Am J Physiol Endocrinol Metab 2001;280:E982–93.

186. Williams AG, van den Oord M, Sharma A, Jones DA. Is glucose/amino acid supplementation after exercise an aid to strength training? Br J Sports Med 2001;35:109–13.

187. Godard MP, Williamson DL, Trappe SW. Oral amino-acid provision does not affect muscle strength or size gains in older men. Med Sci Sports Exerc 2002;34:1126–31.

188. Antonio J, Sanders MS, Ehler LA, et al. Effects of exercise training and amino-acid supplementation on body composition and physical performance in untrained women. Nutrition 2000;16:1043–6.

189. Esmarck B, Andersen JL, Olsen S, et al. Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. J Physiol 2001;535:301–11.

190. Stroescu V, Dragan J, Simionescu L, Stroescu OV. Hormonal and metabolic response in elite female gymnasts undergoing strenuous training and supplementation with SUPRO Brand Isolated Soy Protein. J Sports Med Phys Fitness 2001;41:89–94.

191. Bouthegourd JC, Roseau SM, Makarios-Lahham L, et al. A preexercise alpha-lactalbumin-enriched whey protein meal preserves lipid oxidation and decreases adiposity in rats. Am J Physiol Endocrinol Metab 2002;283:E565–72.

192. Burke DG, Chilibeck PD, Davidson KS, et al. The effect of whey protein supplementation with and without creatine monohydrate combined with resistance training on lean tissue mass and muscle strength. Int J Sport Nutr Exerc Metab 2001;11:349–64.

193. Lands LC, Grey VL, Smountas AA. Effect of supplementation with a cysteine donor on muscular performance. J Appl Physiol 1999;87:1381–5.

194. Demling RH, DeSanti L. Effect of a h

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