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

We investigated whether the injury of skeletal muscle owing to the action o f free radicals and the subsequent oxidative damage to tissues occurred dur ing anaerobic exercise. To estimate injury to skeletal muscle, we determine d certain indices of oxidative damage to skeletal muscle; i.e., leukocyte c ounts, concentrations of hypoxanthine, xanthine, urate, tissue- and serum-t ype CK-M isoforms, myoglobin, and total antioxidant capacity (TAC) of serum . Blood for these tests was collected at 3 min post-exercise. Post-anaerobi c exercise concentrations of lactate were significantly increased from pre- exercise. The neutrophil and lymphocyte counts and alanine concentration we re significantly increased by anaerobic exercise, even when the results wer e corrected for plasma volume changes; the plasma concentrations of hypoxan thine, urate, and TAC of serum were also significantly increased. The plasm a concentration of xanthine was negatively correlated with TAC of serum. Th e activities of tissue- and serum-type CK-M were significantly increased po st-exercise. When the hypoxanthine, urate, TAC of serum, myoglobin, and tis sue- and serum-type CK-M were corrected for plasma volume changes, the post -exercise increases were no longer significantly different from the pre-exe rcise results. We suggest that these latter test results following anaerobi c exercise exclude the presence of oxidative damage to skeletal muscle. (C) 2001 Wiley-Liss, Inc.