Despite anecdotal reports of nausea and muscle cramps, there has been no actual scientific documentation of negative side effects as a result of taking creatine, says Dr. William J. Kraemer, newsletter associate editor and professor of applied physiology at Penn State.

Creatine is a naturally produced amino acid, one that is needed by the body to promote muscle movement during short bursts of intense exercise. For the past six years, its use by athletes and coaches has been growing.

Kraemer and Penn State researcher Jeff Volek M.S., R.D., have been at the forefront of studies on creatine.They recently summarized what is known about creatine supplementation for "Current Comment," a publication of the American College of Sports Medicine.

Their studies have confirmed that, because creatine supplements reduce normal power decline, they enhance performance in short-term bouts of exercise that involve speed and power such as cycling, sprinting, jumping and weightlifting. Athletes who benefit from creatine supplementation may be able to obtain better results because they can train more intensely.

Creatine taken over a 10-12 week period and combined with resistance training produces increases in strength, body mass and fat-free mass. The percentage of body fat and body mass remains relatively constant.

Creatine may work for both men and women engaged in resistance training programs, but men are more likely to show improvement in strength and sprint events and increases in fat-free mass than women. There is no evidence that creatine supplements improve performance in long-duration aerobic exercise, the newsletter says.

Note: If no author is given, the source is cited instead.

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