Avid cyclists over the age of 50 had an improvement in their performance after taking arginine supplements for three weeks, according to a study just published in the International Society of Sports Nutrition. "As people age, their exercise capacity may decline -- leading in turn to a decline in overall fitness that can impact health," noted Luigi Gratton, MD, vice president of medical affairs at Herbalife.
A group of 16 male cyclists, aged 50 to 73 years, were randomly assigned to receive either the supplement (Niteworks; Herbalife International, Los Angeles, CA) containing 5.2 grams of L-arginine, or a look-alike placebo and instructed to continue with their usual cycling regimen over the three week study period.
After three weeks, those taking the supplement had an increase in their anaerobic threshold -- the point at which lactate begins to accumulate in the blood, leading to fatigue.
"Arginine is involved in the production of nitric oxide in the body," notes Gratton, "and nitric oxide has been associated with the improvement of exercise performance through its beneficial effects on the vascular system." As people age, production of nitric oxide declines, so the researchers believed that arginine supplementation could support the production of nitric oxide and enhance performance.
The anaerobic threshold of the study subjects was assessed both before and after the three week study period. In those receiving the supplement, their anaerobic threshold increased by 16.7% after one week, and held steady during the three weeks, whereas those in the placebo group experienced no change.
"This indicates a potential role for arginine in improving exercise performance in older subjects," said Gratton, "and improved performance could mean better fitness and healthier lives."
