Antioxidant supplements are widely used by athletes on both top and recreational level. However, the notion that oxidative stress during exercise may be an important stimulus for the adaptive response to endurance training [1, 2], has questioned the value of taking antioxidant supplements in this population. Consequently, the aim of this study was to investigate the effect of an antioxidant supplement on training induced changes in VO2max in well trained subjects. Methods In a double-blinded placebo controlled design a total of 40 amateur soccer players were randomised into a placebo group or an antioxidant supplemented group (SUP), and 28 of the participants completed the study. The SUP group (n=13) ingested 4+4 capsules per day of a combined antioxidant and vitamin/mineral supplement (LifePak) and the placebo group (n=15) took a similar amount of capsules containing lactose. The supplementation period lasted for six weeks, and before and after the participants were tested for skin caretonid score and VO2max. During the supplementation period all subjects continued their normal training. Results Six week supplementation with the antioxidant vitamin/mineral supplement increased skin caretenoid score by 20±7% while no changes in skin caretenoid score was observed in the placebo group. VO2max increased by 7.5±2.2% in the placebo group while no changes was observed in the SUP group. The relative increase in VO2max was significantly higher in the placebo group than in the SUP group. Discussion The antioxidant vitamin/mineral supplement used in this study reduced training efficiency by blocking the training induced increase in VO2max. Although possible mechanisms behind this finding was not investigated, this result supports the idea that administration of large amounts of antioxidants may reduce the signalling activity in pathways dependent on the formation of reactive oxygen or nitrogen species.
© Copyright 2009 14th annual Congress of the European College of Sport Science, Oslo/Norway, June 24-27, 2009, Book of Abstracts. Published by The Norwegian School of Sport Sciences. All rights reserved.