TRAINING-INDUCED MODIFICATIONS IN SOME BIOCHEMICAL DEFENSES AGAINST FREE-RADICALS IN EQUINE ERYTHROCYTES

Oxidative stress develops when the generation of free radicals exceeds the antioxidant capacity of cells or extracellular fluids. It can als o occur as a result of physical exercise, and the pathogenesis of exer cise-induced myopathies and haemolysis in horses may be related to cha nges in lipid peroxidation caused by free radicals. Cells have develop ed biochemical protection against oxidative stress and, as tissues see m to increase their antioxidant defences under chronic activation, tra ining may be one of the ways of increasing antioxidant defences. Accor dingly we tested some enzymatic antioxidant activities as well as none nzymatic antioxidants in horses undergoing special training. The resul ts indicated a decrease in both chemical and biochemical defences agai nst free radicals during training. It was deduced that the horses' die t may have been unable to provide the increased need for antioxidant d efences resulting from training.