The Role of Antioxidants in Sports and Physical Activity

Physical activity causes a great increase in the body’s oxygen demand. A study published by the journal Sports Medicine in 2001 states that the body has to increase its oxygen uptake 10 to 20 times during an active exercise and that the skeletal  muscle tissues need 100 to 200 times more oxygen supply during repetitive contraction during strenuous exertion.

Because of increased utilization of oxygen within the body during physical activity, the level of reactive oxygen species, the free radicals, increases as well and this may overwhelm the body’s antioxidant defense systems leading to oxidative stress. The intensity of stress brought about by free radicals is highly dependent on the ability of the body to detoxify and ward of free radicals. The body’s supply of antioxidants, which are produced endogenously within the body and from the dietary sources, takes care of the free radical detoxification.

A study published in the August 2007 issue of the Journal of the American College of Nutrition reveals that most of the endurance athletes have lower vitamin and antioxidant intake in proportion to their level of physical activity compared to the general population, which could possibly lead to higher levels of reactive oxygen species. Antioxidant supplementation appears to be most beneficial against the effects of exercise-induced tissue damage of free radicals.

Are there other benefits of antioxidant supplementation in physical activity?

Antioxidant supplementation appears to influence the blood iron status of athletes, says a study conducted by a group of researchers from Community Nutrition and Oxidative Stress Research Group at the University of the Balearic Islands, Spain and published in the April 2004 issue of the International Journal of Sport Nutrition and Exercise Metabolism. Although no changes were seen in the number of red blood cells and hemoglobin concentration in athletes who used antioxidant supplementations and those who did not, the group who did not receive antioxidant supplementation appears to have a higher oxidative stress index and lower serum iron concentration and iron saturation index. As explained by the Office of Dietary Supplements, iron is an essential component of hemoglobin, the protein that carries oxygen within the blood. It is also important for cell development and growth. In fact, a low level of iron results in the limited oxygen delivery to the cells resulting in poor athletic performance and faster muscle fatigue.

Is there danger in the excess use of antioxidant supplementation?

Though numerous benefits can be achieved with ample antioxidant supplementation in athletic performance, excess intake of these supplements appear to have a negative effect too. According to a study published by Sports Medicine in 2009, excessive levels of supplementary antioxidants may actually interfere with the cells detoxification of reactive oxygen species resulting in a poorer muscle performance.

Up to moment, it is not known whether the body’s innate antioxidant defense system is capable of handling strenuous athletic performance. Furthermore, there is still no sufficient direct evidence that can show the additional benefits of exogenous antioxidant supplementation in athletic performance. However, small clinical trials reveal that trained athletes who use antioxidant supplementation have better ability to counteract the effects of oxidative stress within their bodies, thereby improving their muscle performance. Excessive levels of reactive oxygen species abound during athletic performances and these can damage the tissues. Therefore, it is plausible to use antioxidant supplementation prudently since they may also serve as a potent therapeutic tool to replenish the body’s own antioxidant supply. However, the exact dosages for each antioxidant supplement is not yet clearly established, thus competitive athletes should seek to estimate the right dosages fitted for their own physical requirement.

Reference:

• Sports Medicine; Antioxidants in exercise nutrition; Sen, C.K.; 2001
• Sports Medicine; Does antioxidant vitamin supplementation protect against muscle damage?; McGinley, C. et al.; 2009
• International Journal of Sports Nutrition and Exercise Metabolism; Antioxidant diet supplementation influences blood iron status in endurance athletes; Aguilo, A. et al.; April 2004
• Journal of the American College of Nutrition; Nutritional and plasmatic antioxidant vitamins status of ultra endurance athletes; Machefer, G. et al.; August 2007
• The American Journal of Clinical Nutrition; Antioxidants: what role do they play in physical activity and health?; Clarkson, P.M. and Thompson, H.S.; August 2000
• Office of Dietary Supplements: Iron