EFFECTS OF EXERCISE TRAINING AND DECONDITIONING ON PLATELET-FUNCTION IN MEN

Platelets play an important role in the pathogenesis of cardiovascular disease. It has also been noticed that regular exercise can reduce th e risk of cardiovascular disease. This is the first study to demonstra te that endurance exercise training may suppress platelet adhesiveness and aggregation and that deconditioning may reverse the training effe cts. Healthy male sedentary subjects were randomly divided into contro l and training groups. The trained men were trained on a bicycle ergom eter at about 60% of maximal oxygen consumption for 30 minutes per day , 5 days per week for 8 weeks, then deconditioned for 12 weeks. During the experimental period, blood samples of the trained subjects were c ollected before and immediately after a progressive exercise test ever y 4 weeks. The same experiments were applied to the controls at the be ginning of this study and 8 weeks thereafter. A tapered parallel-plate chamber was used to assess platelet adhesiveness. Platelet aggregatio n induced by ADP was evaluated by the percentage of reduction in singl e platelet count. Our results showed that (1) platelet adhesiveness an d aggregability were increased by short-term strenuous exercise in bot h control and trained groups, but the enhancement of platelet aggregab ility was decreased after exercise training in the trained subjects; ( 2) at rest and immediately after strenuous exercise, platelet adhesive ness and aggregability were decreased by training, whereas they were u nchanged in the control group; and (3) deconditioning reversed the tra ining effects on resting and postexercise platelet adhesiveness and ag gregability back to the pretraining state. These results suggest that platelet adhesiveness and aggregability may be depressed by exercise t raining but be reversed back to the pretraining state after deconditio ning.