Effect of vitamin supplementation on cytokine response and on muscle damage after strenuous exercise

The present double-blinded, placebo-controlled study investigated whether a ntioxidant vitamin supplementation was able to modulate the cytokine and ly mphocyte responses after strenuous eccentric exercise. Furthermore, muscle enzyme release was examined to see whether antioxidant treatment could redu ce muscle damage. Twenty male recreational runners randomly received either antioxidants (500 mg of vitamin C and 400 mg of vitamin E) or placebo for 14 days before and 7 days after a 5% downhill 90-min treadmill run at 75% ( V) over dot O-2 max. Although the supplemented group differed significantly with regard to plasma vitamin concentration before and after exercise when compared with the placebo group, the two groups showed identical exercise- induced changes in cytokine, muscle enzyme, and lymphocyte subpopulations. The plasma level of interleukin (IL)-6 and IL-1 receptor antagonist increas ed 20- and 3-fold after exercise. The plasma level of creatine kinase was i ncreased sixfold the day after exercise. The concentrations of CD4(+) memor y T cells, CD8(+) memory and naive T cells, and natural killer cells increa sed at the end of exercise. The total lymphocyte concentration was below pr evalues in the postexercise period. In conclusion, the present study does n ot support the idea that exercise-induced inflammatory responses are induce d by free oxygen radicals.