Changes in blood catecholamine levels and blood coagulation and fibrinolytic activity in response to graded exercise in man.

Measurements of catecholamines, fibrinogen, factor VIII, thrombelastography, euglobulin lysis time and platelet adhesiveness have been carried out on venous blood obtained from normal males exposed to exercise on a bicycle ergometer at various work loads. Significant increases in adrenaline, factor VIII and fibrinogen were found only after exercise to exhaustion at 1500 kpm min-1 whereas the euglobulin lysis time was inversely proportional to the excercise load. There was no change in platelet adhesiveness. These findings support the results of studies using adrenaline infusions or adrenergic blockade which suggest that stress-induced increases in factor VIII are mediated via adrenergic stimulation but that activation of fibrinolysis is not dependent on adrenaline.