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 con trols (Con). After training, a more pronounced increase in factor VIII coagulant activity (P < 0.01), reflected in a decrease in activated p artial thromboplastin time (P < 0.01) during maximal exercise, was see n. 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 d ecreased after training. The overall effect on fibrinolysis was reflec ted in an increase in the t-PA Act/t-PA Ag ratio in the Tr group. In c ontrast, during the same period (February-June), the Con group demonst rated 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). Bo th 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 phys ical training promotes both coagulation and fibrinolytic potential dur ing exercise and may reverse unfavorable seasonal effects on fibrinoly sis.