EFFECT OF TWO DIFFERENT DOSES OF VITAMIN C SUPPLEMENTATION ON EXERCISE-INDUCED LIPID PEROXIDATION AND MUSCLE DAMAGE

Abstract

Oxygen free radicals are highly reactive species that are produced in increased quantities during strenuous exercise and can damage critical biological targets such as membrane phospholipids. The purpose of this study was to compare effects of high or moderate doses of vitamin C (vitC) supplementation on exercise-induced oxidative stress and muscle damage. Twenty-four healthy untrained males performed a 30-min exercise test at 75% VO2max. Subjects were randomly assigned to one of three groups: placebo (P, lactose), moderate dose (MD, 500 mg vitC) and high dose (HD, 1000 mg vitC). Blood samples were obtained prior to and 2h after supplementing; immediately, 2h and 24h following exercise. Analysis of covariance for repeated measures was used to detect statistical significance of between- and within-subject differences. Plasma levels of vitC and malondialdehyde (MDA), total antioxidant capacity (TAC) and creatine kinase (CK) activity were measured. Plasma vitC levels increased 2h after supplementation, and continued even 2h after exercise in both supplemented groups (p<0.05). TAC decreased significantly only in the P group, 24 h after exercise (p<0.05). CK increased immediately and 2h after exercise in all groups, and 24h after exercise only in the placebo group, compared with the pre-exercise state (p<0.05). Although MDA levels were similar among groups at baseline, it increased significantly 2h after exercise only in the P group (p<0.05). Both types of vitC supplementation are likely effective in preventing muscle damage and exercise-induced lipid peroxidation. There is no apparent need to supplement vitamin C in high doses.