Principal Proposed Natural Treatments
Two natural supplements have shown meaningful promise as ergogenic aids: creatine and hydroxymethyl butyrate.
Creatine. Creatine, one of the best-selling and
best-documented supplements for enhancing athletic performance, is a naturally
occurring substance that plays an important role in the production of energy in
the body. The body converts creatine to phosphocreatine, a form of stored energy
used by muscles. In theory, taking supplemental creatine will build up a reserve
of phosphocreatine in the muscles to help them perform on demand. Supplemental
creatine may also help the body make new phosphocreatine faster when it has been
used up by intense activity. However, the balance of evidence suggests that if
creatine supplements have any benefit for sports performance, it is slight and
limited to highly specific forms of exercise.
Several small double-blind studies have found that creatine can improve performance in exercises that involve repeated short bursts of high-intensity activity with intervening rest periods of adequate length. A double-blind, placebo-controlled study investigated creatine and swimming performance in eighteen men and fourteen women. Men taking the supplement had significant increases in speed when doing six bouts of fifty-meter swims started at three-minute intervals, compared to men taking placebo. However, their speed did not improve when swimming ten sets of twenty-five-yard lengths started at one-minute intervals. Researchers theorize that the shorter rest time between laps was not enough for the swimmers’ bodies to resynthesize phosphocreatine.
None of the women enrolled in the study showed any improvement with the creatine supplement. The authors of this study noted that women normally have more creatine in their muscle tissue than do men, so perhaps creatine supplementation (at least at this level) is not of benefit to women, as it appears to be for men. Further research is needed to fully understand the difference between the genders in response to creatine.
In an earlier double-blind study, sixteen physical education students carried out ten six-second bursts of extremely intense exercise on a stationary bicycle, separated by thirty seconds of rest. The results showed that the students who took 20 grams (g) of creatine for six days were better able to maintain cycle speed throughout the repetitions. Many other studies showed similar improvements in performance capacity involving repeated bursts of action. However, there have been negative results too; in general, minimal to no benefits have been seen in studies involving athletes engaged in normal sports rather than contrived laboratory tests.
In contrast, studies of endurance or nonrepetitive aerobic-burst exercise generally have not shown benefits from creatine supplementation. Therefore, creatine probably will not help with marathon running or single sprints.
In addition to repetitive burst exercise, creatine has also shown promise for increasing isometric exercise capacity (pushing against a fixed resistance). Also, two double-blind, placebo-controlled studies, each lasting twenty-eight days, provide some evidence that creatine and creatine plus hydroxymethyl butyrate can increase lean muscle and bone mass. However, one double-blind trial failed to find creatine helpful for enhancing general fitness, including resistance exercise performance, in elderly men. The contradictory results seen in these small trials suggest that creatine offers at most a very modest sports performance benefit.
Hydroxymethyl butyrate
. Beta-hydroxy beta-methylbutyric acid (HMB) is a chemical that occurs naturally in the body when the amino acid leucine breaks down. Leucine is found in particularly high concentrations in muscles. During athletic training, damage to the muscles leads to the breakdown of leucine and to increased HMB levels. Some evidence suggests that taking HMB supplements might signal the body to slow down the destruction of muscle tissue. On this basis, HMB has been studied as a sports performance supplement for enhancing strength and muscle mass.
According to many of the small double-blind trials that have been reported, HMB appears to improve muscle-growth response to weight training. For example, in a controlled study, forty-one male volunteers age nineteen to twenty-nine years were given either 0, 1.5, or 3 g of HMB daily for three weeks. The participants also lifted weights three days per week according to a defined (and rather severe) schedule. The results suggested that HMB can enhance strength and muscle mass in direct proportion to intake.
In another controlled study reported in the same article, thirty-two male volunteers took either 3 g of HMB or placebo daily and then lifted weights for two or three hours daily, six days per week, for seven weeks. The HMB group saw a significantly greater increase in bench-press strength than the placebo group. However, there was no significant difference in body weight or fat mass by the end of the study.
Similarly, a double-blind, placebo-controlled trial of thirty-nine men and thirty-six women found that in four weeks, HMB supplementation improved response to weight training. Two placebo-controlled studies of women found that 3 g of HMB had no effect on lean body mass and strength in sedentary women, but it did provide an additional benefit when combined with weight training. Also, a double-blind study of thirty-one men and women, all seventy years old and undergoing resistance training, found significant improvements in fat-free mass attributable to the use of HMB (3 g daily).
However, there have been negative studies too, but all were small, so their results are ultimately not reliable. Larger studies will be necessary to truly establish whether HMB is helpful for power athletes working to enhance strength and muscle mass.
Other Proposed Natural Treatments
Numerous other supplements are marketed as ergogenic aids, said to improve speed, strength, or endurance. However, the evidence that they work is marginal at best, and in many cases the best available evidence indicates that these substances are not effective.
Ginseng. There are three different herbs commonly called
ginseng: Asian or Korean ginseng (Panax
ginseng), American ginseng (Panax quinquefolius), and
Siberian ginseng (Eleutherococcus senticosus). The latter is not
truly ginseng, but the Russian scientists responsible for promoting it believed
that it functioned identically and named it ginseng. According to some experts, a
fourth herb, ciwujia, is actually Eleutherococcus, while others
claim it is a related but different species.
Ginseng has shown some promise as a mild ergogenic aid, but published evidence remains at best incomplete and contradictory. Other forms of ginseng generally lack any meaningful supporting evidence.
For example, an eight-week, double-blind, placebo-controlled trial evaluated the effects of P. ginseng with and without exercise in forty-one people. The participants were given either P. ginseng or placebo and then underwent exercise training or remained untrained throughout the study. The results showed that ginseng improved aerobic capacity in people who did not exercise but offered no benefit in those who did exercise.
In a nine-week, double-blind, placebo-controlled trial of thirty highly trained athletes, treatment with P. ginseng or P. ginseng plus vitamin E produced significant improvements in aerobic capacity. Another double-blind, placebo-controlled trial of thirty-seven participants also found some benefit. Also, a double-blind, placebo-controlled study of 120 people found that P. ginseng gradually improved reaction time and lung function in a twelve-week treatment period among participants from forty to sixty years of age. (No benefits were seen in younger people.)
However, in an eight-week double-blind trial that followed sixty healthy men in their twenties, no benefit with P. ginseng could be demonstrated. Many other small trials of P. ginseng have failed to find evidence of benefit. These mixed outcomes suggest that ginseng is only slightly effective at best.
A double-blind study of twenty endurance athletes in eight weeks failed to find evidence of benefit with a standard Eleutherococcus formulation. Furthermore, in a small, double-blind, placebo-controlled trial of endurance athletes, the use of Eleutherococcus actually increased physiologic signs of stress during intensive training. Ciwujia has not yet been studied in meaningful double-blind trials.
Medium-chain triglycerides. Medium-chain triglycerides
(MCTs) are fats with an unusual chemical structure that
allows the body to digest them easily. Most fats are broken down in the intestine
and reassembled into a special form that can be transported in the blood. However,
MCTs are absorbed intact and taken to the liver, where they are used directly for
energy. In this sense, they are processed like carbohydrates. For that reason,
MCTs have been proposed as an alternative to carbo-loading (consumption of a large
quantity of carbohydrates before intense physical exercise) for providing a
concentrated source of easily utilized energy.
A number of double-blind studies have evaluated MCTs’ effects on high-intensity or endurance exercise performance, but the results have been thoroughly inconsistent. This is not surprising because all of the studies were too small to properly eliminate the effects of chance.
Iron. The majority of athletes are probably not iron-deficient, and people should not take iron supplements if they already have enough iron in their bodies. However, if a person is deficient in this essential mineral, iron supplements may enhance athletic training.
A double-blind, placebo-controlled trial of forty-two nonanemic women with evidence of slightly low iron reserves found that iron supplements significantly increased the benefits gained from exercise. Participants were put on a daily aerobic training program for the latter four weeks of this six-week trial. At the end of the trial, those receiving iron showed significantly greater gains in speed and endurance than those given placebo. In addition, a double-blind, placebo-controlled study of forty nonanemic elite athletes with mildly low iron stores found that twelve weeks of iron supplementation enhanced aerobic performance.
Benefits with iron supplementation for marginally iron-depleted athletes were observed in other double-blind trials too. However, several other studies failed to find significant improvements. These contradictory results suggest that the benefits of iron supplements for nonanemic, iron-deficient athletes is small at most.
Colostrum. Colostrum is the fluid that new
mothers’ breasts produce during the first day or two after birth. Colostrum
contains growth factors, such as IGF-1, that could enhance muscle development, and
on this basis it has been tried as a sports supplement.
An eight-week double-blind study found that the use of colostrum enhanced sprinting performance. Other double-blind studies found improvements in rowing performance and in vertical jump.
In addition, one small double-blind study found that colostrum, compared to whey protein, increased lean mass in healthy men and women undergoing aerobic and resistance training. However, no improvements in performance were seen in this trial.
Finally, in a double-blind, placebo-controlled study, the use of colostrum in an eight-week training period did not improve performance on an exercise-to-exhaustion test; however, it did improve performance on a repeat bout twenty minutes later. Research suggests that the growth factor IGF-1 in colostrum is not directly absorbed into the body, yet consumption of colostrum nonetheless increases IGF-1 levels in the blood, perhaps by stimulating its natural release.
Pyruvate. Pyruvate, also called dihydroxyacetone
pyruvate, supplies the body with pyruvic acid, a natural compound that plays
important roles in the manufacture and use of energy. Pyruvate supplements have
become popular with bodybuilders and other athletes based on slim evidence that
pyruvate can improve body composition. However, the evidence regarding pyruvate as
an ergogenic aid is weak and contradictory at best. One study failed to find that
pyruvate supplements improved body composition or exercise performance;
furthermore, pyruvate appeared to negate the beneficial effect of exercise on
cholesterol profile.
Policosanol. Policosanol is a mixture of waxy
substances manufactured from sugarcane. It contains octacosanol, which is also
made from wheat germ oil. Both are marketed as performance-enhancing dietary
supplements said to increase muscle strength and endurance and to improve reaction
time and stamina. However, the only evidence for policosanol as a performance
enhancer comes from one small double-blind trial with marginal results.
Phosphatidylserine. Phosphatidylserine (PS) is a phospholipid and a major component of cell membranes. Good evidence suggests that PS can improve mental function, especially in the elderly. However, PS has also been marketed as a sports supplement, said to help bodybuilders and power athletes develop larger and stronger muscles. This claim is based on modest evidence indicating that PS slows the release of cortisol following heavy exercise.
Cortisol is a hormone that causes muscle tissue to break down. For reasons that are unclear, the body produces increased levels of cortisol after heavy exercise. Strength athletes who believe natural cortisol release works against their efforts to rapidly build muscle mass hope that PS will help them advance more quickly. However, only two double-blind, placebo-controlled studies of PS as a sports supplement have been reported, and neither found effects on cortisol levels. Of these small trials, one found a possible ergogenic benefit and the other did not.
Another study evaluated the use of phosphatidylserine for improving the performance of golfers. While improvement in perceived stress levels failed to reach statistical significance, participants who were given phosphatidylserine did tee-off successfully at a greater rate than those given placebo.
Branched-chain amino acids: leucine, isoleucine, and valine.
Amino acids are molecules that form proteins when joined together. Three of them
(leucine, isoleucine, and valine) are called branched-chain amino acids
(BCAAs), a term that describes the shape of the molecules.
Muscles have a particularly high BCAA content.
Both strength training and endurance exercise use greater amounts of BCAAs than normal daily activities, perhaps increasing an athlete’s need for dietary intake of these amino acids. Sports such as mountaineering and skiing may cause even greater depletion of BCAAs because of metabolic changes that occur at higher altitudes. Athletes have tried BCAA supplements to build muscle, improve performance, postpone fatigue, and cure overtraining syndrome (prolonged fatigue and other symptoms caused by excessive exercise). However, most of the evidence suggests that BCAAs are not helpful for these purposes.
Whey protein is rich in BCAAs, and on this basis, it has also been proposed as a bodybuilding aid. However, there is little evidence that whey protein is more effective for this purpose than any other protein. One small double-blind study found evidence that both casein and whey protein were more effective than placebo at promoting muscle growth after exercise, but whey was no more effective than the far less expensive casein. Another study failed to find benefits with combined whey and soy protein supplementation. However, a single small study did find ergogenic benefits with whey compared to casein.
Other amino acids. Besides BCAAs, athletes use a number of other amino acids, sometimes individually and sometimes in combination. Amino acids believed by some to have ergogenic effects include arginine, glutamine, and ornithine (ornithine and glutamine combined form ornithine alpha-ketoglutarate), and the branched-chain amino acids leucine, isoleucine, and valine. However, evidence supporting the use of amino acids as ergogenic aids is sparse to nonexistent. The few clinical trials performed generally do not show positive results.
Carnitine. Carnitine, a substance closely related
to amino acids, is used by the body to convert fat into energy. Even though the
body can manufacture all it needs, supplemental carnitine could, in theory,
improve the ability of certain tissues to produce energy, leading to its promotion
as a sports performance enhancer. However, there is no meaningful evidence that
this is the case.
Chromium. The mineral chromium has been sold as a “fat burner” and is also said to help build muscle tissue. However, studies evaluating its benefits as a performance enhancer and studies assessing its effectiveness as an aid to bodybuilding have yielded almost entirely negative results.
Coenzyme Q
10. Coenzyme Q10 (CoQ10) is a natural substance that plays a fundamental role in the mitochondria, the parts of the cell that produce energy from food. On this basis, CoQ10 has been proposed as a performance enhancer for athletes. However, most clinical trials have found no significant improvement with the use of CoQ10.
Inosine. Inosine is an important chemical found
throughout the body. It plays many roles, one of which is helping to make ATP, the
body’s main form of usable energy. Based primarily on this fact, inosine
supplements have been proposed as an energy booster for athletes. However, most of
the available evidence suggests that it does not work.
Ribose. Ribose is a carbohydrate that is also
vital for the manufacture of ATP. Ribose has shown some promise for improving
exercise capacity in people with certain enzyme deficiencies and other rare
conditions that cause muscle pain during exertion. On this basis, it has been
touted as an athletic performance enhancer; however, six small, double-blind,
placebo-controlled trials in humans failed to find any benefit. In one of these
studies, dextrose (a form of ordinary sugar), proved effective while ribose did
not.
Gamma oryzanol. Preliminary evidence suggests that
gamma
oryzanol, a substance derived from rice bran oil, may
increase endorphin release and aid muscle development. These findings have created
interest in using gamma oryzanol as a sports supplement. However, a nine-week,
double-blind, placebo-controlled trial of twenty-two weight-trained males found no
difference between placebo and 500 mg daily of gamma oryzanol in terms of
performance, body composition, or hormone levels.
Trimethylglycine. Trimethylglycine (TMG) is a naturally
occurring compound that may help to prevent atherosclerosis. It is, therefore,
sometimes taken as a supplement. In the course of its metabolism in the body, TMG
is turned into another substance, dimethylglycine (DMG).
In Russia, DMG is used extensively as an athletic performance enhancer, and it has recently become popular among American athletes. TMG is less expensive, and it may have the same effects as DMG, inasmch as it changes into DMG in the body. However, there is no evidence that DMG is effective and even some evidence that it is not.
Dehydroepiandrosterone. Athletes have used dehydroepiandrosterone (DHEA) on the belief that (like phosphatidylserine) it might limit the body’s response to cortisol and thereby cause an increase in muscle tissue growth. However, study results have not established whether or not DHEA really interferes with cortisol. Furthermore, studies of DHEA as an aid to increasing muscle mass or enhancing sports performance have produced mixed results at best.
Tribulus terrestris. Tribulus terrestris is a tropical plant with a long history of medicinal use. It has been tried for low libido in both men and women, and for impotence and female infertility.
One theory regarding how T. terrestris might help with sexual disorders is that a component from the plant called protodioscine is converted into the hormone DHEA in the body. DHEA is used by the body as a building block for both testosterone and estrogen (and other hormones). This finding has led bodybuilders and strength athletes to try T. terrestris for increasing muscular development. However, the scientific evidence seems to be against it. This is not surprising, because DHEA itself has not been found effective as a sports supplement.
One study involving fifteen men compared the effects of T. terrestris (3.21 mg per kilogram of body weight; for example, 292 mg daily for a two-hundred-pound man) with placebo on body composition and endurance among men engaged in resistance training. At the end of the eight-week study, the only significant difference between the treatment and placebo groups was that the placebo group showed greater gains in endurance.
Another double-blind, placebo-controlled study, which enrolled twenty-two athletes and followed them for five weeks, failed to find benefit. The dose used in this trial was fixed at 450 mg daily for all participants.
Phosphate. Because phosphate plays a fundamental role in the body’s energy-producing pathways, it has been suggested that taking high doses of phosphate (phosphate loading) before athletic activities might enhance performance. Phosphate-containing chemicals are also part of the process that allows oxygen release from hemoglobin, and this too has intrigued researchers looking for ergogenic aids. However, while some studies have found that phosphate loading improves maximum oxygen utilization, others have not. Flaws in study design cast doubt on the positive results.
Commercial preparations. A small double-blind study of a mixture of various herbs and supplements marketed as SPORT found no evidence that it can improve sports performance in trained athletes.
Stimulants: Ma huang and caffeine. A number of plant-derived
stimulants are used by some athletes to improve their performance. These
stimulants include ephedrine from the Chinese herb ma
huang (also called ephedra) and caffeine from coffee, tea, maté, cola,
or guarana (a plant native to South America). Both ephedrine and caffeine are
central nervous system stimulants. Caffeine also appears to change the way the
body burns calories, possibly allowing it to burn fats first and preserve muscle
glycogen for later in an athletic performance (in a way, “saving the best for
last”).
Caffeine does appear to improve performance during endurance-type exercises. The International Olympic Committee has set a tolerance limit for caffeine in the urine at 12 micrograms per milliliter.
Ephedrine’s value in enhancing sports performance has not been established; at the same time, there are serious safety issues associated with its use. Some sports federations have determined that specific amounts of ephedrine in an athlete’s system are grounds for disqualification.
Other. One small double-blind trial found that the use of the herb Rhodiola rosea improved endurance exercise performance. However, another study failed to find benefit with a combination of Cordyceps and Rhodiola.
A variety of antioxidants have been proposed for enhancing recovery after
heavy exercise. One study found weak evidence that a combination of vitamin E (400
mg daily) and vitamin C (1,000 mg daily) taken for three weeks can improve aerobic
performance.
Heavy exercise causes increased calcium loss through sweat, and the body does not compensate for this by reducing calcium loss in the urine. The result can be a net calcium loss great enough so that it presents health concerns for menopausal women, who are already at risk for osteoporosis. One study found that the use of an inexpensive calcium supplement (calcium carbonate), taken at a dose of 400 mg twice daily, is sufficient to offset this loss.
A small study found endurance exercise benefits with the herb Panax notoginseng. Another small trial suggests that acupuncture may enhance peak performance capacity. Weak evidence hints that arachidonic acid supplements might enhance response to resistance training.
The use of a low-glycemic-index snack three hours before endurance running may be more helpful than a high-glycemic-index (carbohydrate) snack. However, another study failed to find benefit.
Galactose is a type of sugar that the body combines with glucose to create lactose (“milk sugar”). For various theoretical reasons, it has been hypothesized that the use of galactose might enhance endurance exercise performance. However, the one small study designed to test this hypothesis found, instead, that the consumption of galactose before endurance exercise actually proved detrimental.
A small double-blind study failed to find any performance or training-enhancing benefits with a newly marketed silicate product. Also failing to show benefit in preliminary trials are astaxanthin, fish oil, N-acetylcysteine, soy isoflavones, and tyrosine.
Numerous other natural substances have been marketed as ergogenic aids, despite an essentially absolute absence of evidence that they help. These substances include Cordyceps, Cystoseira canariensis, deer antler, ipriflavone, lipoic acid, methoxyisoflavone, nicotinamide adenine dinucleotide, and suma. One study found that L-citrulline, another purported ergogenic aid, actually decreases exercise capacity.
Many marketers sell products that they claim will act like human growth hormone, often called HGH enhancers. However, these products are entirely speculative because there are no natural treatments proven to raise human growth hormone levels. Similarly, there are no herbs or supplements known to act as “natural anabolic steroids.”
One small study failed to find benefit with a liquid multivitamin-multimineral supplement. Also, the amino acid beta-alanine is said to raise levels of carnosine, which in turn is hypothesized to enhance performance in athletes undergoing resistance training. However, a double-blind study of twenty-six athletes failed to find benefit with 6 g of alanine daily.
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