Supplement May Give Older Athletes an Edge

March 26, 2010 -- Cyclists who are 50 and older may be able to ride farther
and faster if they take a commercially available supplement containing the
amino acid arginine and antioxidants that help boost the body’s natural
exercise capabilities, according to new research in the Journal of the
International Society of Sports Nutrition.
“The loss of exercise capacity with age often results in a reduction in
physical fitness and more rapid [cell death],�? says researcher Zhaoping Li, MD,
of the University of California at Los Angeles. “A dietary supplement that
increases exercise capacity might help to preserve physical fitness by
optimizing performance and improving general health and well being in older
people.�?
Niteworks, made by Herbalife International, is a lemon-flavored powder that
is mixed with water. It contains 5.2 grams of L-arginine and L-citrulline, 300
milligrams of L-taurine, 500 milligrams of vitamin C, 400 international units
(IU) of vitamin E, 400 micrograms of folic acid, 10 milligrams of alpha lipoic
acid, and 50 milligrams of lemon balm extract.
Our bodies’ production of nitric oxide tends to dim with advancing age.
Nitric oxide helps stimulate the blood vessels around the heart and other
organs to dilate, and it also plays a role in increasing exercise capacity.
Arginine is a precursor to nitric oxide development. Nitric oxide production
is also hampered by damaging free radicals. Antioxidants, such as those
contained in the new supplement, sop up these free radicals, stopping them in
their tracks. The new supplement hits nitric oxide from both ends -- triggering
its production with arginine and preventing its destruction with
antioxidants.
 
Exercise Capacity and Nitric Oxide
In the new study of 16 male cyclists aged 50 to 73, men who were given the
supplement showed a 16.7% increase in their anaerobic threshold at three weeks.
By contrast, their counterparts who received the placebo did not see any
increase in their anaerobic thresholds. Anaerobic threshold is the point at
which lactic acid starts to accumulate in the muscles and is known as a
powerful predictor of performance in aerobic exercise.
“We have just studied elderly since human exercise capacity declines with
advancing age and many individuals lose the inclination to participate in
regular physical activity,�? Li tells WebMD. “Our study has shown that the
supplements help the muscles work much more efficiently in our study
population.
Study participants took the supplements at bedtime, which is when nitric
oxide levels are lowest. Arginine may dilate the blood vessels and cause
dizziness when standing, which is another reason to take the supplement before
bed, Li says.
Study volunteers did not show any evidence of heart disease. The role of
L-arginine among people with heart disease is considered controversial, study
authors say.
“It is also unclear if arginine supplementation in the sedentary population
can have the same results," the study authors write. They say further research
is needed.
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