Locomotor Muscle Metaboreflex Activation Augments Blood Pressure During Exercise In Post-menopausal Women

Post-menopausal women have an exaggerated blood pressure response during submaximal exercise, in part due to heightened systemic vascular resistance (SVR). One potential mechanism contributing to the exaggerated blood pressure response post-menopause is alterations in the metaboreflex, the metabolically sensitive component of the exercise pressor reflex. PURPOSE: We hypothesized that metaboreflex stimulation during exercise would lead to greater increases in mean arterial pressure (MAP) via SVR for post-menopausal women compared to pre-menopausal women. METHODS: Healthy pre-menopausal (n = 11, 31 ± 7 years, 23 ± 4 kg/m2) and post-menopausal (n = 9, 57 ± 7 years, 24 ± 3 kg/m2) women completed two study visits. On the first study visit, single legged peak cycling workload was determined. On the second study visit, participants completed two single legged exercise bouts at 50% peak single leg workload. The single legged exercise bouts consisted of 4 min of left-legged cycling exercise followed by either normal recovery (control condition) or left-leg suprasystolic circulatory occlusion (metaboreflex condition). Immediately following cessation of left-legged exercise, participants performed right-legged exercise for 4 min with or without left-leg suprasystolic circulatory occlusion. MAP was measured via arterial catheter, cardiac output (Q) via open circuit wash-in technique, and SVR was calculated. The difference in MAP, Q, and SVR between the metaboreflex and control conditions during right-legged exercise are reported. RESULTS: The metaboreflex condition (compared to the control condition) resulted in greater increases in MAP for post-menopausal women than pre-menopausal women during right legged exercise (10.3 ± 4.3 vs. 6.3 ± 3.2 mmHg; p = 0.03). The metaboreflex condition (compared to the control condition) resulted in greater increases in SVR for post-menopausal women than pre-menopausal women during right legged exercise (2.0 ± 0.6 vs. 0.7 ± 1.0 mmHg/L/min; p < 0.01). The change in Q between conditions during right legged exercise was not different between groups (-0.3 ± 0.3 vs. 0.0 ± 0.4 L/min; p = 0.12). CONCLUSIONS: These findings support our hypothesis that metaboreflex stimulation elicits greater increases in MAP and SVR during exercise for post-menopausal women than pre-menopausal women. Supported by: K12 AR84222