Introduction
In the competitive world of sports, the smallest advantage can make an enormous difference in the outcome of a contest. A dietary supplement that could improve an athlete’s strength, speed, or endurance could make the difference between, say, tenth place and first place in a race.
Supplements could conceivably play another helpful role for athletes: aiding recovery from the side effects of intense exercise. While exercise of moderate intensity is almost undoubtedly a purely positive activity, high-intensity endurance exercise, such as running marathons, can cause respiratory infections. In addition, all forms of exercise, when carried to extreme, can cause severe muscle soreness, which may in turn affect training. Herbs and supplements advocated for these problems are discussed here.
Principal Proposed Natural Treatments
Extremely intense exercise, such as training for and running in a marathon, is
known to lower immunity, and endurance athletes frequently get sick after maximal
exertion. Vitamin
C might help prevent this, although not all studies
agree.
According to a double-blind, placebo-controlled study involving ninety-two runners, taking 600 milligrams of vitamin C for twenty-one days before a race made a significant difference in the incidence of sickness afterward. Within two weeks of the end of the race, 68 percent of the runners taking placebo developed symptoms of a common cold, whereas only 33 percent of those taking the vitamin C supplement developed cold symptoms. As part of the same study, nonrunners of the same gender and similar age to those running were also given vitamin C or placebo. For this group, the supplement had no apparent effect on the incidence of upper respiratory infections. Vitamin C seemed to be specifically effective in this capacity for those who exercised intensively.
Two other studies found that vitamin C could reduce the number of colds experienced by groups of people involved in rigorous exercise in extremely cold environments. One study involved 139 children attending a skiing camp in the Swiss Alps, while the other enrolled 56 military men engaged in a training exercise in Northern Canada during the winter months. In both cases, the participants took either 1 gram (g) of vitamin C or placebo daily at the time their training program began. Cold symptoms were monitored for one to two weeks following training, and significant differences in favor of vitamin C were found.
However, one very large study of 674 U.S. Marine Corps recruits found no such benefit. The results showed no difference in the number of colds between the treatment and placebo groups.
There are many possible explanations for this discrepancy. Perhaps basic training in the Marine Corps is significantly different from the other forms of exercise studied. Another point to consider is that the recruits did not start taking vitamin C at the beginning of training, but waited three weeks before doing so. The study also lasted a bit longer than the earlier positive studies. Perhaps vitamin C is more effective at preventing colds in the short term. Of course, another possibility is that vitamin C does not work.
Other Proposed Natural Treatments
Like vitamin C, the amino acid glutamine may be helpful for preventing
the infections that occur after severe exercise. Glutamine is an important fuel
source for some immune system cells. Some evidence suggests that athletes who have
trained very hard have lower-than-normal levels of glutamine in their blood. One
double-blind clinical trial involving 151 athletes found that supplementation with
5 g of glutamine immediately after heavy exercise, followed by another 5 g two
hours later, reduced the incidence of infections significantly. Only 19 percent of
those taking glutamine reported infections, while 51 percent of the placebo group
succumbed to illness.
Probiotics are healthy organisms found in the digestive
tract. Not only can they help prevent intestinal infections, they appear also to
help prevent colds. In a double-blind, controlled trial involving twenty healthy,
elite distance runners, researchers found that a probiotic supplement
(Lactobacillus fermentum) given for four months during winter
training was significantly more effective at reducing the number and severity of
respiratory symptoms compared with placebo. Weaker evidence suggests that
beta-sitosterol might also offer some promise for this purpose. However,
thymus
extract, another proposed immune booster for athletes, does
not seem to work, according to a double-blind, placebo-controlled trial of sixty
athletes.
Exercising increases the presence of free radicals, naturally occurring
substances that can damage tissue. Some researchers have theorized that such
damage may in part cause the muscle soreness, and perhaps muscle deterioration,
that can accompany a strenuous workout. Based on this theory, but on little direct
evidence, various antioxidants have been proposed to help prevent muscle
soreness or muscle damage. These antioxidants include astaxanthin plus lycopene,
beta-carotene, cherry juice, coenzyme Q10, oligomeric
proanthocyanidins, selenium, vitamin C, and vitamin E. One double-blind trial
compared vitamin C, vitamin E, and placebo for muscle soreness in twenty-four male
volunteers. Vitamin C relieved muscle soreness, but E did not. Two other studies
failed to find C combined with E effective. Another study failed to find benefit
with the algae-derived carotenoid astaxanthin.
One small double-blind study found that the use of a mixed amino acid reduced muscle soreness caused by endurance exercising of the arm. These researchers actually performed two studies. The first involved simply taking the amino acid thirty minutes before exercising; this study failed to find benefit. The second, more effective regimen added one dose immediately after exercise and two doses daily for the next four days. In addition, a specific family of amino acids, branched-chain amino acids, have shown some promise for reducing muscle damage after long-distance running.
The proteolytic enzyme supplement bromelain, used for sports injuries,
has also been proposed for reducing muscle soreness after exercise. However, a
double-blind, placebo-controlled trial that compared bromelain with placebo failed
to find benefit. Another study, this one using a mixed proteolytic enzyme
supplement, also failed to find benefits.
Collagen hydrolysate is a nutritional supplement that may benefit cartilage tissue in joints. In a randomized, placebo-controlled study involving healthy college athletes with joint pain, 10 g daily of collagen hydrolysate appeared to effectively reduce the pain in a period of twenty-four weeks.
The supplement phosphatidylserine has also failed to prove effective for reducing
muscle soreness after exercise, as have chondroitin and magnet therapy. In one
study, the supplement glucosamine not only failed to prove effective for reducing
exercise-induced muscle soreness; it actually increased soreness.
Athletes who train excessively may experience a condition called overtraining
syndrome. Symptoms include depression, fatigue, reduced
performance, and physiologic signs of stress. Numerous supplements have been
suggested as treatments for this condition, including glutamine and, most
prominently, antioxidants, but none have been proven effective.
Bibliography
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Avery, N. G., et al. “Effects of Vitamin E Supplementation on Recovery from Repeated Bouts of Resistance Exercise.” Journal of Strength and Conditioning Research 17 (2003): 801-809.
Beck, T. W., et al. “Effects of a Protease Supplement on Eccentric Exercise-Induced Markers of Delayed-Onset Muscle Soreness and Muscle Damage.” Journal of Strength and Conditioning Research 21 (2007): 661-667.
Bloomer, R. J., et al. “Astaxanthin Supplementation Does Not Attenuate Muscle Injury Following Eccentric Exercise in Resistance-Trained Men.” International Journal of Sport Nutrition and Exercise Metabolism 15 (2005): 401-412.
Braun, W. A., et al. “The Effects of Chondroitin Sulfate Supplementation on Indices of Muscle Damage Induced by Eccentric Arm Exercise.” Journal of Sports Medicine and Physical Fitness 45 (2006): 553-560.
Cox, A. J., et al. “Oral Administration of the Probiotic Lactobacillus fermentum VRI-003 and Mucosal Immunity in Endurance Athletes.” British Journal of Sports Medicine 44 (2010): 222-226.
Koba, T., et al. “Branched-Chain Amino Acids Supplementation Attenuates the Accumulation of Blood Lactate Dehydrogenase During Distance Running.” Journal of Sports Medicine and Physical Fitness 47 (2007): 316-322.
Mastaloudis, A., et al. “Antioxidants Did Not Prevent Muscle Damage in Response to an Ultramarathon Run.” Medicine and Science in Sports and Exercise 38 (2006): 72-80.
Nosaka, K., P. Sacco, and K. Mawatari. “Effects of Amino Acid Supplementation on Muscle Soreness and Damage.” International Journal of Sport Nutrition and Exercise Metabolism 16 (2006): 620-635.
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