[Selenium metabolism and glutathione peroxidase activity of endurance athletes in rest and under exertion]

Selenium which has been recognised as an essential trace element for mammals and humans is part of the enzyme glutathione peroxidase (GSHPx) and of other selenium-dependent enzymes. GSHPx protects the organism from oxidative damage. Supposing that the formation of peroxides is enhanced in athletes during a marathon run the question arose whether the selenium concentrations in the blood plasma and the GSHPx activities in the erythrocytes are changed. Our experiments were performed with 13 athletes completing a marathon. Blood probes were taken before, immediately after and two hours after the endurance event. No significant changes in the selenium concentrations of the blood plasma probes nor of the enzyme glutathione peroxidase activities of the erythrocytes were observed during the experiments. The selenium concentrations in the plasma: 77.7 +/- 20.8 micrograms/l and the GSHPx activities of the erythrocytes 18.2 +/- 7.4 U/g Hb were within normal clinical range. Symptoms of selenium deficiency could not be detected. In order to answer the question of whether the selenium concentrations in the blood of the athletes represent an optimal level for preventing enhanced formation of peroxides, intervention studies are needed, including measurement of more parameters of lipid peroxidation.