Antioxidant Supplementation and Markers of Muscle Damage, Oxidative Stress, and Muscle Soreness After Downhill Running
Feng He Medicine & Science in Sports & Exercise. 45(5S): 681, May 2013.
Eccentric exercise produces muscle damage and delayed onset muscle soreness (DOMS), increases oxidative stress, and provides a protective effect that attenuates these responses following a subsequent eccentric exercise. The mechanisms involved in muscle damage and DOMS are not entirely known, but increased oxidative stress is thought to be a contributor.
PURPOSE: To investigate the effect of antioxidant supplementation on markers of muscle damage (creatine kinase activity: CK), oxidative stress (oxygen radical absorbance capacity: ORAC), and DOMS after repeated downhill runs.
METHODS: Moderately trained males were randomly assigned to a supplement (S) (age: 20.5±0.7 yr; VO2max: 54.6±1.7 ml/kg/min; n=11) or placebo (P) (age: 21.3±1.2; VO2max: 53.1±0.9; n=11) group. Capsules containing 1000 mg vitamin C and 400 IU vitamin E (or maltodextrin for P) were ingested daily for 2 wk before the first (1D) and second (2D) downhill runs (65-70% VO2max, -10% grade, 40 min) and continued for 2 additional days. Trials were separated by 3 wk. CK (U/L) and ORAC (µM Trolox/ml serum) were measured before (PRE), after (0 h), and at 6, 24, and 48 h postexercise (POST). DOMS was rated for front thigh, back thigh, buttocks, calf, and shin at 0, 24, 48 and 72 h POST (0-6 pt scale). Data were analyzed using repeated measures mixed model ANOVA and adjusted Tukey post hoc tests.
RESULTS: Participants had lower CK (P< 0.01), higher ORAC (P<0.05), and less DOMS (P< 0.01) following 2D vs 1D. CK at 48 h following 1D remained elevated above PRE in P (311±95 vs 109±28) (P<0.01) but not in S. DOMS of the front thigh was lower in S (1.1±0.3) than P (2.2±0.5) (P<0.05). There was no significant change in DOMS of the front thigh or shin from 0-72 h POST after 1D in S but DOMS in these muscle groups was higher (P<0.05) at 24 and 48 h vs 72 h after 1D in P. At 24 h POST in S, CK was lower (P<0.01) and ORAC was higher (P<0.05) following 2D (CK: 109±18; ORAC: 12478±1792) than 1D (CK: 283±48; ORAC: 7572±1610).
CONCLUSION: Supplementation attenuated the increase in CK activity and DOMS in the front thigh and shin after 1D. CK and oxidative stress following 2D were blunted in response to 1D; antioxidant supplementation enhanced this protective effect as indicated by an attenuation of biomarkers of muscle damage and a boost in antioxidant capacity observed 24 h POST.