Antioxidant Supplementation and Endurance Training Adaptation
Yfanti, C., Akerstrom, T., Nielsen, S., et al. Antioxidant supplementation does not alter endurance training adaptation. Med Sci Sports Exerc. 2010;42:1388-1395.
Reactive oxygen and nitrogen species production that occurs with exercise may negatively impact performance; however, this same process appears to be critical in stimulating desired training adaptations. The purpose of this study was to investigate whether vitamin C and E supplementation during endurance training attenuates the expected increase in training adaptation and performance in physically active men. IN this 12-week, double-blind, placebo-controlled study, 21 men (ages 18-40 g) completed a 5-day per week intensive cycle training protocol.
Eleven participants received 500 mg vitamin C and 400 IU vitamin E daily for 16 weeks (AO group); the remaining 10 participants received placebo tablets (PL group). Plasma levels of vitamin C and E were monitored along with dietary intake. performance and oxidative capacity were assessed using aerobic and metabolic parameters that included maximal oxygen consumption (VO2max), maximal power output, workload at lactate threshold, skeletal muscle glycogen content, and mitochondrial enzymes (citrate synthase and beta-hydroxyacacyl-CoA dehydrogenase). Plasma levels of vitamins C and E increased significantly (P<.05 and P<.001 respectively) in the AO group and remained unchanged in the PL group. Both groups had significant improvements from baseline in the aerobic and metabolic parameters (P<.01), but no significant difference was detected between groups. the results of this study indicate that vitamin C and E supplementation does not attenuate training adaptation or improve performance in physically active men.
In conclusion, athletes with normal vitamin C and E status will most likely experience neither positive no negative effects secondary to antioxidant supplementation.