Improved antioxidative protection in winter swimmers

Adaptation to oxidative stress is an improved ability to resist the damagin g effects of reactive oxygen species, resulting from pre-exposure to a lowe r dose. Changes in uric acid and glutathione levels during ice-bathing sugg est that the intensive voluntary short-term cold exposure of winter swimmin g produces oxidative stress. We investigated whether the repeated oxidative stress in winter swimmers results in improved antioxidative adaptation. We obtained venous blood samples from winter swimmers and determined importan t components of the antioxidative defense system in the erythrocytes or blo od plasma: reduced and oxidized glutathione (GSH and GSSG), and the activit ies of superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalas e (Cat). The control group consisted of healthy people who had never partic ipated in winter swimming. The baseline concentration of GSH and the activi ties of erythrocytic SOD and Cat, were higher in winter swimmers. We interp ret this as an adaptative response to repeated oxidative stress, and postul ate it as a new basic molecular mechanism of increased tolerance to environ mental stress.