Changes in plasma antioxidant status during eccentric exercise and the effect of vitamin supplementation.

Twenty-four healthy students undertook one hour of box-stepping exercise. Prior to exercise eight had received no medication (Group A), eight received 400 mg of vitamin C daily for three weeks before and one week after exercise (Group C) and eight received 400 mg of vitamin E for the same period (Group E). Groups C and E had significantly higher levels of vitamin C (p < 0.01) and vitamin E (p < 0.01) respectively than group A at the commencement of exercise. Plasma total antioxidant capacity rose significantly during exercise in all group (A - p < 0.05; C - p < 0.001; E - p < 0.001). This rise was accounted for by increases in plasma uric acid in all groups. In addition there were significant increases in vitamin C in group C (p < 0.001) and vitamin E in group E (p < 0.05). There were no significant changes in plasma malondialdehyde following exercise in any group. It is concluded that plasma antioxidant capacity rises in response to one hour of eccentric exercise and that the contribution of individual antioxidants to this change can be influenced by vitamin supplementation. The possible mechanisms of the antioxidant changes during exercise and their implications are discussed.