The Durk Pearson & Sandy Shaw^®
Life Extension News^TM
Volume 6 No. 3 • June 2003

Xanthine Oxidase and Muscle Damage in Strenuous Exercise

In a Research Letter of a recent JAMA,¹ researchers noted that the xanthine oxidase free radical-generating enzyme is involved in ischemia-reperfusion syndrome and may cause damage associated with exhaustive exercise. They therefore tested the effect of allopurinol, an inhibitor of xanthine oxidase, on the level of muscle damage in athletes after participating in the Tour de France bicycle race versus athletes receiving placebo.

The nine members of the U.S. Postal (U.S. Snail!) cycling team were randomly divided into two groups. One group of four was given a daily oral dose of 300 mg of allopurinol one hour before each racing stage; the other group received placebo at the same time.

Those who had received placebo had an increase in the activities of creatine kinase and aspartate aminotransferase, indicating muscle damage, only after the team trial stage where participants were putting out peak effort. There was no such change seen in those who received allopurinol. The researchers also found increased levels of malondialdehyde (an indication of lipid peroxidation) in all participants, but significantly higher levels were found in those on placebo compared to those receiving allopurinol.

There was no difference in performance between the two groups.

1. Gomez-Cabrera et al. Allopurinol and markers of muscle damage among participants in the Tour de France. JAMA 289(19):2503-4 (2003).