It is currently unknown if sex differences exist in the cardiovascular consequences of the inspiratory muscle metaboreflex. We hypothesized that the activation of the inspiratory muscle metaboreflex will lead to less of an increase in mean arterial pressure (MAP) and limb vascular resistance (LVR) and less of a decrease in limb blood flow (Q̇L) in women compared to men. Twenty healthy men (n=10, 23 ± 2 yrs) and women (n=10, 22 ± 3 yrs) were recruited for this study. Subjects performed inspiratory resistive breathing tasks (IRBTs) at 2% or 65% of their maximal inspiratory mouth pressure (PIMAX). During the IRBTs, the breathing frequency was 20 breaths min-1 with a 50% duty cycle. At rest and during the IRBTs, MAP was measured via automated oscillometry, Q̇L was measured via Doppler ultrasound, and LVR was calculated. EMG was recorded on the leg to ensure no muscle contraction occurred. The 65% IRBT led to attenuated increases (p<0.01) from baseline in women compared to men for MAP (W: 7.3±2.0 mmHg; M: 11.1±5.0 mmHg) and LVR (W: 17.7%±14.0%; M: 47.9±21.0%) as well as less of a decrease (p<0.01) in Q̇L (W: -7.5±9.9%; M: -23.3±10.2%). These sex differences in MAP, Q̇L, and LVR were still present in a subset of subjects matched for PIMAX. The 2% IRBT resulted in no significant changes in MAP, Q̇L, or LVR across time or between men and women. These data indicate pre-menopausal women exhibit an attenuated inspiratory muscle metaboreflex compared to age-matched men.
- sex differences
- blood pressure
- limb vascular resistance
- Copyright © 2016, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology