Active Voice: Can Antioxidants Give Your Performance a Boost?

By Katie M. Slattery, Ph.D.

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM. Katie M. Slattery, Ph.D., is a Senior Sports Scientist in exercise physiology at the New South Wales Institute of Sport in Australia. Katie completed her Ph.D. at the University of Technology, Sydney, Australia, where she investigated the effects of antioxidants on exercise performance and training adaptation. She also holds the position of conjoint fellow at the University of Newcastle Australia, undertaking research in the area of hypoxia and resistance training. Katie is also part of the Sports Science Advisory Group for Exercise and Sports Science Australia.

This commentary presents Dr. Slattery’s views on the topic of a research article which she and her colleagues have authored and which appears in the June 2014 issue of Medicine and Science in Sports and Exercise® (MSSE).

Many athletes habitually take antioxidant supplements to maintain health and well-being. Some expect the antioxidant properties of substances like cherry juice, quercetin or N-acteylcysteine (NAC) will improve sporting performance, without concern that the intake of antioxidants may have a potentially detrimental effect on not only their exercise capacity, but also their ability to adapt to physical training. While there is ample evidence to suggest that antioxidants can support individuals in their athletic pursuits, recent research suggests that a high dose of antioxidants may, in fact, block beneficial cellular processes and impair performance. It has become apparent that a delicate balance exists between dietary antioxidant intake and management of exercise-induced oxidative stress. It may be that supplementation is only warranted for acute ergogenic effects or during periods of increased stress such as occur with periods of strenuous training, illness or altitude exposure.

To examine these questions, we conducted a study to determine the effect of supplementation with the antioxidant NAC on performance and exercise-induced changes within the oxidative and inflammatory systems (June 2014 issue of MSSE). NAC is a thiol-containing compound, which acts as a cysteine donor to minimize oxidative damage and has been shown to promote fatigue resistance during intensive exercise. It is one of the only antioxidant supplements that has regularly been shown to have an ergogenic effect on performance. However, these effects are often observed when NAC is infused intravenously — a means of administration not useful in a practical sporting setting.