Effects of exercise training and deconditioning on platelet aggregation induced by alternating shear stress in men

Objective - Alternating shear stress, which resembles the flow condition in stenotic arteries, induces platelet aggregation. This study investigated how exercise training and deconditioning influence alternating shear-induced platelet aggregation (ASIPA) and clarify the mechanisms underlying ASIPA. Methods and Results - Thirty healthy male sedentary subjects were randomly divided into control and trained groups. The trained men were trained on a bicycle ergometer at approximate to 60% of maximal oxygen consumption for 30 minutes per day, 5 days per week for 8 weeks, and then were deconditioned for 8 weeks. The experimental results indicate the following: ( 1) short-term strenuous exercise increases the extent of ASIPA and is accompanied by increased the von Willebrand factor (vWF) binding and P-selectin expression on platelets in both the control and trained groups, whereas the enhancement of platelet function decreases after exercise training in trained subjects; ( 2) at rest and immediately after exercise, ASIPA and the vWF binding and P-selectin expression on platelets are reduced by training, but remain unchanged in the control group; and ( 3) deconditioning reverses the effects of training on resting and postexercise state. Conclusions - Exercise training suppresses the extent of ASIPA, probably by reducing vWF binding to platelets and P-selectin expression on platelets. However, deconditioning reverses the training effects.