METABOLIC RESPONSE TO LIGHT EXERCISE AFTER EXERCISE-INDUCED RHABDOMYOLYSIS

Abstract

Inherent compromises in substrate metabolism or impaired perfusion of the muscle may contribute to the occurrence of exercise-induced rhabdomyolysis. The present study examined lactic acid response of the elbow flexor muscles to light exercise in subjects who previously demonstrated rhabdomyolysis with profound swelling of the arm after high-force eccentric exercise. We hypothesized that there would be a difference in the lactate response to exercise in those exhibiting profound swelling compared to those who demonstrated no signs of swelling from an eccentric exercise protocol (50 maximal eccentric contractions of the elbow flexors) in a previous study performed approximately 30 days prior to the present study. 8 college-age subjects (5 males, 3 females) participated in the study; displaying extreme swelling (ES; n = 4) or no swelling (NS; n = 4) of the upper arm. Subjects performed two consecutive days of identical light exercise on each subject's previously eccentrically exercised arm (E-ARM) and the control arm that did not previously perform eccentric exercise (C-ARM). The light exercise bout was 45 seconds of rapid biceps curls at 25% MVC until fatigue. Blood lactate (BLA) was assessed 1.5, 3, 4.5, 6, and 9 minutes post-exercise. Baseline BLA was subtracted from peak BLA and the differences between arms or between groups were compared using the non-parametric Mann-Whitney U. In the ES group, the increase in BLA after biceps curls exercise with the C-ARM (Δ1.98 ± 0.7 mmol/l) was not significantly different from the increase after exercising the E-ARM (Δ2.10 ± 0.7 mmol/l) (p > 0.05). In the NS group, the increase in BLA after biceps curls exercise with the C-ARM (Δ1.30 ± 0.4 mmol/l) was not significantly different from the increase after exercising the E-ARM (Δ1.40 ± 0.4 mmol/l) (p > 0.05). When comparing the response of the E-ARM between groups, the increase in BLA of NS (Δ1.40 ± 0.4 mmol/l) was not significantly different than the increase of ES (Δ2.10 ± 0.7 mmol/l) (p > 0.05). The current study did not demonstrate changes in the metabolic response during fatiguing exercise in subjects who had exhibited signs of exercise-induced rhabdomyolysis compared to those who responded normally to eccentric exercise.