Metabolic response to light exercise after exercise-induced rhabdomyolysis.

Inherent compromises in substrate metabolism, or impaired perfusion of muscle may contribute to the occurrence of exercise-induced rhabdomyolysis. In this study, the lactate response of the elbow flexor muscles to light exercise was examined in eight subjects (five males, three females) who previously demonstrated rhabdomyolysis with extreme swelling (ES; n = 4) or no swelling (NS; n = 4) of the upper arm after eccentric exercise. Subjects performed identical light exercise bouts (45 s of rapid isotonic biceps curls consisting of both concentric and eccentric actions at 25% of maximum voluntary contraction force) using their previously eccentrically exercised arm (E-ARM) and control arm, which was not used previously to perform eccentric exercise (C-ARM). Blood lactate concentration ([La]b) was assessed 1.5, 3, 4.5, 6, and 9 min post-exercise. Peak [La]b and the area under the curve (AUC) were compared between the E-ARM of the ES and NS groups and between the C-ARM and E-ARM of the ES group. The AUC did not differ between the E-ARM of the ES and NS groups (P > 0.05) or between the C-ARM and E-ARM of the ES group (P > 0.05). In the ES group, the increase in [La]b after light exercise with the C-ARM [mean (SD) change, delta: 1.98 (0.7) mmol/l] was not different from the increase after exercising the E-ARM [delta: 2.10 (0.7) mmol/l; P>0.05]. Comparing the response of the E-ARM between groups, the increase in [La]b of the NS group [delta: 1.40 (0.4) mmol/l] was not different than that observed in the ES group [delta: 2.10 (0.7) mmol/l; P>0.05). Thus, subjects who had previously exhibited signs of exercise-induced rhabdomyolysis did not show an abnormal response to low-intensity anaerobic exercise.