Exercise-Induced Catecholamines

Catecholamines and platelet aggregation were studied in relation to physical fitness and psychologic traits of 48 young men at rest and after exercise challenge. Test scores were significantly associated with variables derived from the in vitro reactivity of blood platelets. Men characterized by high time urgency, impatience, haste and irritability had higher platelet counts in their whole blood. They also had less of a decrease in percent of platelet aggregation in response to noradrenalin after exercise, a shorter duration of platelet aggregation time in response to ADP and a greater likelihood of irreversible "second slope" aggregation than the less hurried, more calm men. Men scoring high on the Type A or coronary-prone behavior scale also failed to show a decrease in percent of platelet aggregation in response to noradrenalin after the challenge of exercise, and, in addition, the duration of the aggregation to ADP was much shorter in Type As at rest and relatively unaffected by exercise. In general, Type A men were distinguishable from Type Bs, not so much by their resting values, but by their differential physiologic mobilization to the challenge of exercise. The primary focus of this study was to consider changes in plasma catecholamines and the reactive properties of blood platelets in terms of the psychologic and behavioral characteristics of the people from whom the plasma and platelets were drawn. The possible clinical implications remain to be determined.