EFFECT OF ANTIOXIDANT SUPPLEMENTATION ON INDICIES OF MUSCLE DAMAGE FOLLOWING PROLONGED INTERMITTENT SHUTTLE RUNNING

Abstract

Oxidative stress has been linked to ultrastructural muscle damage both during and in the days following prolonged exhaustive or unaccustomed exercise. The role of antioxidants in reducing this damage is still to be fully elucidated. PURPOSE The aim of this investigation was to determine whether the protective effects observed with single antioxidant supplementation could be replicated with a mixed antioxidant. METHODS Thirty eight males who were 22±1 yrs (mean±S.D.) with a body mass of 77.4±8.3 kg, height of 1.79±0.1 m and a maximal oxygen uptake of 61.4± 5.3 ml.kg−1.min−1 were divided into two groups and randomly assigned to six weeks supplementation of either a placebo (PL) or a mixed antioxidant (AT), containing ascorbic acid (800 mg), α-tocopherol (800 IU), zinc (5 mg), vitamin B6 (2 mg) B12 (1 mcg) and folic acid (200 mcg). Following supplementation subjects completed the 90-min Loughborough Intermittent Shuttle Test (LIST). Serum markers of muscle damage were monitored up to 48 h post-exercise. Isometric maximal voluntary contraction (MVC) and range of motion (ROM) of the leg extensors and flexors were monitored up to seven days post-exercise. RESULTS Following supplementation with (AT) recovery of force production in the leg extensors, assessed as change in MVC from pre-exercise, was greater at 168 h (110±3%) when compared to (p < L) (88±3%, p < 0.01). Recovery of ROM was also greatest in the (AT) group (108±2 °) compared with the (p < L) group (103±2 °, p ≤ 0.05). Although no effect of supplementation was observed serum concentrations of myoglobin increased 1 h post-exercise (35.86±7.01 nmol.L−1, p < 0.05) and creatine kinase activity increased 24 h post-exercise (1366±243 IU.L−1, p < 0.01). CONCLUSION Although we observed modest beneficial effects on muscle function with the mixed antioxidant supplement, these effects were not as pronounced as with single antioxidant supplements.