Oxidative stress in athletes: From the scientific basis to practical aspects

Abstract

Oxidative stress, which occurs as a result of physical exercise, has been intensively investigated in the last two decades. A large number of studies have been done on humans and in animal models, which resulted in clarification of the mechanism of free radical generation during exercise. Free radicals, unstable and reactive molecules that can be involved in cellular damage, are mainly generated by the mitochondria, xanthine oxidase, and neutrophils and other phagocytes. Increased production of free radicals during exercise is followed by the enhanced activity of the endogenous antioxidant defense system, which consists of enzymes and non-enzymatic substances. Very important results of previous studies have been related to adaptation mechanisms activated in response to increased oxidative stress during exercise. In addition to mitochondrial biogenesis and synthesis of new components of the respiratory chain to match higher energy demands, adaptation to regular physical exercise involves an increased expression of genes responsible for antioxidant enzyme synthesis. Also, great attention has been paid to the use of antioxidant supplements. The importance and effect of supplementation with dietary antioxidants depend on several factors such as intensity, frequency and mode of exercise as well as on the type and dose of the antioxidants used. Applying the results of previous research and monitoring the parameters of oxidative stress and antioxidative defense could help health professionals in understanding the medical condition of the athlete.