ANTIOXIDANT SUPPLEMENTATION HAS NO EFFECT ON MUSCLE DAMAGE FOLLOWING AN ULTRAMARATHON RUN

Abstract

PURPOSE To determine if prolonged antioxidant (AO) supplementation enhances recovery from endurance exercise-induced muscle damage. METHODS 22 runners consumed either placebos or AO (400 IU vitamin E and 2 × 500 mg vitamin C) daily for 6 w prior to and 1 w after a 50 k ultramarathon. All subjects consumed a prescribed diet low in vitamins E and C for the 7 w of the study; foods limited in AO were provided for subjects on race day. An isokinetic dynanometer was used to determine concentric and eccentric maximal voluntary contractions (MVC) in quadriceps and hamstrings. Measurements were taken at baseline, 1 d pre-race, 2 h post-race, and daily for 6 d post-race. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) were assessed at additional time points: pre-, mid- and post-race. Energy expenditure (EE) was calculated for each individual using the average heart rate (HR) during the run (recorded by HR monitors) and previously measured VO2. RESULTS All subjects completed the race; run time was 7.1 ± 0.1 h; EE was 5008 ± 80 for women (N=11) and 6932 ± 206 Kcal for men (N=11). Compared to pre-race, CK was elevated at mid-, post, 2 h post-, and peaked at 1 d post- (17-fold increase, p > 0.0001) returning to baseline 6 d post-race. LDH was elevated at mid-, peaked at post- and remained elevated for 2 d post-race (p < 0.03). MVC were depressed at 2 h post- (p < 0.05) compared to 1 d pre-race. Concentric quadriceps MVC remained depressed until 3 d post- (p < 0.009) while concentric hamstring MVC recovered by 2 d post-race (p < 0.02). Eccentric quadriceps MVC recovered by 1 d post-, but eccentric hamstring MVC did not recover until 3 d post-race. CONCLUSION Endurance exercise resulted in a reduction in MVC and increased plasma muscle damage markers indicating that the exercise bout was strenuous enough to cause persistent muscle damage and fatigue. Most importantly, AO supplements had no effect on the severity of the muscle damage markers, MVC impairment or on recovery rates. Supported by NIH Grant ES1153