Is skeletal muscle damaged by the oxidative stress following anaerobic exercise?

We investigated whether the injury of skeletal muscle owing to the action of free radicals and the subsequent oxidative damage to tissues occurred during anaerobic exercise. To estimate injury to skeletal muscle, we determined certain indices of oxidative damage to skeletal muscle; i.e., leukocyte counts, concentrations of hypoxanthine, xanthine, urate, tissue- and serum-type CK-M isoforms, myoglobin, and total antioxidant capacity (TAC) of serum. Blood for these tests was collected at 3 min post-exercise. Post-anaerobic exercise concentrations of lactate were significantly increased from pre-exercise. The neutrophil and lymphocyte counts and alanine concentration were significantly increased by anaerobic exercise, even when the results were corrected for plasma volume changes; the plasma concentrations of hypoxanthine, urate, and TAC of serum were also significantly increased. The plasma concentration of xanthine was negatively correlated with TAC of serum. The activities of tissue- and serum-type CK-M were significantly increased post-exercise. When the hypoxanthine, urate, TAC of serum, myoglobin, and tissue- and serum-type CK-M were corrected for plasma volume changes, the post-exercise increases were no longer significantly different from the pre-exercise results. We suggest that these latter test results following anaerobic exercise exclude the presence of oxidative damage to skeletal muscle.