BACKGROUND: The risk of atherothrombotic events increases after menopause. Regular physical activity has been shown to reduce platelet reactivity in younger women, but it is unknown how regular exercise affects platelet function after menopause.

OBJECTIVES: To examine the effects of regular aerobic exercise in late pre- and recent postmenopausal women by testing basal platelet reactivity and platelet sensitivity to prostacyclin and nitric oxide.

METHODS: 25 sedentary, but healthy, late premenopausal and 24 matched recently postmenopausal women, mean (95% confidence interval) 49.1 (48.2-49.9) and 53.7 (52.5-55.0) years old, participated in an intervention study: 3-month high-intensity supervised aerobic spinning-cycle training (1hr, x3/week). Basal platelet reactivity was analyzed in platelet rich plasma from venous blood as agonist-induced %aggregation. In a subgroup of 13 pre- and 14 postmenopausal women, platelet reactivity was tested ex vivo after femoral arterial infusion of prostacyclin, acetylcholine, a cyclooxygenase inhibitor and after acute one-leg knee extensor exercise.

RESULTS: Basal platelet reactivity (%aggregation) to TRAP-6(1μM) was higher in the postmenopausal; 59% (50-68) versus premenopausal women; 45% (35-55). Exercise training reduced basal platelet reactivity to collagen(1μg/ml) in the premenopausal women only; from 63% (55-71%) to 51% (41-62%). After the training intervention, platelet aggregation was more inhibited by the arterial prostacyclin infusion and the acute exercise in both pre- and postmenopausal women.

CONCLUSIONS: These results highlight previously unknown cardioprotective aspects of regular aerobic exercise in pre- and postmenopausal women, improving their regulation of platelet reactivity through an increased platelet sensitivity to prostacyclin, which may counterbalance the increased atherothrombotic risk associated with menopause. This article is protected by copyright. All rights reserved.