EFFECTS OF CHRONIC EXERCISE AND DECONDITIONING ON PLATELET-FUNCTION IN WOMEN

To investigate the effects of chronic exercise and deconditioning on p latelet function in women, 16 healthy sedentary women were divided int o control and exercise groups. The exercise group cycled on an ergomet er at 50% maximal oxygen consumption for 30 min/day, 5 days/wk, for tw o consecutive menstrual cycles and then were deconditioned for three m enstrual cycles. During this period, platelet adhesiveness on a fibrin ogen-coated surface, ADP-induced platelet aggregation and intracellula r calcium concentration elevation, guanosine 3',5'-cyclic monophosphat e (cGMP) content in platelets, and plasma nitric oxide metabolite leve ls were measured before and immediately after a progressive exercise t est in the midfollicular phase. Our results indicated that, after exer cise training, 1) resting heart rates and blood pressures were reduced , and exercise performance was improved; 2) resting platelet function was decreased, whereas plasma nitrite and nitrate levels and platelet cGMP contents were enhanced; and 3) the potentiation of platelet funct ion by acute strenuous exercise was decreased, whereas the increases i n plasma nitrite and nitrate levels and platelet cGMP contents were en hanced by acute exercise. Furthermore, deconditioning reversed these t raining effects. This implies that training-induced platelet functiona l changes in women in the midfollicular phase may be mediated by nitri c oxide.