Effect of endurance training and seasonal fluctuation on coagulation and fibrinolysis in young sedentary men.

The effect of 12 wk of submaximal training on hemostatic variables was studied in 20 young sedentary men (Tr) and 19 nontraining matched controls (Con). After training, a more pronounced increase in factor VIII coagulant activity (P < 0.01), reflected in a decrease in activated partial thromboplastin time (P < 0.01) during maximal exercise, was seen. Both basal plasminogen activator inhibitor 1 antigen (PAI-1 Ag) and activity (PAI-1 Act; P < 0.05), as well as basal and exercise-induced tissue-type plasminogen activator antigen (t-PA Ag; P < 0.05), were decreased after training. The overall effect on fibrinolysis was reflected in an increase in the t-PA Act/t-PA Ag ratio in the Tr group. In contrast, during the same period (February-June), the Con group demonstrated an increase in basal PAI-1 Ag and PAI-1 Act (P < 0.05), together with an increase in basal and exercise-induced t-PA Ag (P < 0.05). Both basal and exercise-induced t-PA Act were unchanged, but t-PA Act/t-PA Ag was decreased (P < 0.05) in the Con group. We conclude that physical training promotes both coagulation and fibrinolytic potential during exercise and may reverse unfavorable seasonal effects on fibrinolysis.