Unbalanced haemostatic changes following strenuous physical exercise. A study in young sedentary males.

During acute exercise both coagulant and fibrinolytic potential increase. Since strenuous exertion is associated with an enhanced risk for cardiac events, especially in untrained individuals, it is important to determine whether the initial haemostatic balance is maintained during exercise. Twenty-nine sedentary males (20-30 years) were subjected to a standardized cycle ergometer test. Blood samples were obtained at two exercise levels, 70% VO2max (submaximal), 100% VO2max (maximal) and during 25 min recovery. Both during submaximal and maximal performance, tissue type plasminogen activator antigen, urokinase plasminogen activator antigen and tissue type plasminogen activator activity were increased. A concomitant enhancement of clotting activity of factors VII, VIII, IX, XII and fibrinogen resulted in a shortening of clotting times. Following correction for changes in plasma volume, the results 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 plasminogen activator activity) potential proceeded in parallel during exercise. However, during recovery while there was a sustained increase in coagulant potential, fibrinolytic potential demonstrated a sharp fall. We conclude that during physical activity, while parallel changes in coagulant and fibrinolytic activity occur, this haemostatic balance is not maintained during recovery. This phenomenon could constitute an enhanced risk for coronary artery thrombosis which may contribute to exercise-related cardiovascular events.