UNBALANCED HEMOSTATIC CHANGES FOLLOWING STRENUOUS PHYSICAL EXERCISE -A STUDY IN YOUNG SEDENTARY MALES

During acute exercise both coagulant and fibrinolytic potential increa se. Since strenuous exertion is associated with an enhanced risk for c ardiac events, especially in untrained individuals, it is important to determine whether the initial haemostatic balance is maintained durin g exercise. Twenty-nine sedentary males (20-30 years) were subjected t o a standardized cycle ergometer test. Blood samples were obtained at two exercise levels, 70% VO(2)max (submaximal), 100% VO(2)max (maximal ) and during 25 min recovery. Both during submaximal and maximal perfo rmance, tissue type plasminogen activator antigen, urokinase plasminog en activator antigen and tissue type plasminogen activator activity we re increased. A concomitant enhancement of clotting activity of factor s VII, VIII, IX, XII and fibrinogen resulted in a shortening of clotti ng times. Following correction for changes in plasma volume, the resul ts for factor VII:c were reversed, and factor XII:c and fibrinogen no longer demonstrated exercise-related changes. Increases in coagulant ( activated partial thromboplastin time) and fibrinolytic (tissue type p lasminogen activator activity) potential proceeded in parallel during exercise. However, during recovery while there was a sustained increas e in coagulant potential, fibrinolytic potential demonstrated a sharp fall. We conclude that during physical activity, while parallel change s in coagulant and fibrinolytic activity occur, this haemostatic balan ce is not maintained during recovery. This phenomenon could constitute and enhanced risk for coronary artery thrombosis which may contribute to exercise-related cardiovascular events.