Participation in regular physical activity reduces the risk of developing diabetes, cardiovascular and other lifestyle-dependent diseases. Interestingly, acute and strenuous exercise influences platelet function and platelet leukocyte interaction as well as blood coagulation and fibrinolysis. However, the underlying mechanisms of these interactions are still completely understood. Accordingly, in the present study we investigated the effect of High-intensity endurance competition (HIC) on platelet function and activity. In addition, we investigated also effects of blood lactate (BLa) on platelet function.