Skeletal muscle metaboreflex is enhanced in postmenopausal women

Abstract

This study determined whether an elevated muscle metaboreflex contributes to the excessive blood pressure response to exercise in postmenopausal women. Thirty healthy female volunteers were studied (15 postmenopausal and 15 premenopausal). Stroke volume, heart rate, cardiac output (CO), systolic blood pressure, diastolic blood pressure, and total vascular conductance (TVC) were continuously assessed throughout the experiment. To activate the muscle metaboreflex, occlusion of the vasculature was induced via inflation of a blood pressure cuff (2 min) on the upper arm following static handgrip exercise. Muscle metaboreflex activation increased mean arterial pressure (MAP) in both groups. However, this pressor response was greater in the postmenopausal women (ΔMAP: 21.4 ± 3 vs. 14.5 ± 2 mmHg) (P < 0.05) even though the corresponding increase in CO was less (ΔCO: 0.0 ± 0.2 vs. 0.3 ± 0.2 l/min) (P < 0.05). TVC decreased in both the groups but was more pronounced in the postmenopausal group (ΔTVC: -10.7 ± 2.6 vs. -17.1 ± 3.6 ml/min/mmHg) (P < 0.05). In conclusion, the exaggerated blood pressure response to exercise in postmenopausal women is mediated, in part, by an overactive metaboreflex that is associated with enhanced peripheral vasoconstriction.