Potential ergogenic effects of L-arginine against oxidative and inflammatory stress induced by acute exercise in aging rats.

In this study, we report protective effects of dietary L-arginine (L-Arg) supplementation against oxidative stress and inflammation in aging rats during exhaustive exercise. Thirty 18-month-old male Sprague-Dawley rats were randomly divided into four groups: sedentary control (SC); sedentary control with L-Arg treatment (SC+Arg); exhaustive exercise (E); and exhaustive exercise with L-Arg treatment (E+Arg). Rats in groups SC+Arg and E+Arg received a 2% L-Arg diet. Rats in groups E and E+Arg performed an exhaustive running test on a treadmill. The mean duration of exercise differed significantly between groups E and E+Arg (51+/-6 versus 63+/-3min). Results showed significant increases in xanthine oxidase (XO) and myeloperoxidase (MPO) activities and in lipid peroxidation end-product (malondialdehyde, MDA) levels of myocardial, muscular, hepatic, pulmonary, and renal tissues of exercised rats compared with SC and SC+Arg rats. The increased XO and MPO activities and MDA levels significantly decreased in exercised rats that were fed a diet supplemented with L-Arg. We also found that L-Arg supplementation prevented exhaustive exercise-induced elevations of plasma aminotransferase activity, and lactate and uric acid levels in aging rats. These findings suggest that L-Arg supplementation enhances exercise capacity and protects against oxidative damage and inflammatory responses caused by exhaustive exercise in aging rats.