Cardiovascular consequences of the inspiratory muscle metaboreflex: effects of age and sex

With inspiratory muscle metaboreflex activation, we hypothesized that, compared with their younger counterparts, older men and women would exhibit greater 1) increases in mean arterial pressure (MAP) and limb vascular resistance (LVR) and 2) decreases in limb blood flow (QL) but 3) no sex differences would be present in older adults. Sixteen young adults [8 young men (YM) and 8 young women (YW), 18–24 yr] and 16 older adults [8 older men (OM) and 8 older women (OW), 60–73 yr] performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths/min with a 50% duty cycle. At baseline and during the IRBTs, MAP was measured via automated oscillometry, QL was determined via Doppler ultrasound, and LVR was calculated. The 65% IRBT led to significantly greater increases in MAP in OW (15.9 ± 8.1 mmHg) compared with YW (6.9 ± 1.4 mmHg) but not (P > 0.05) between OM (12.3 ± 5.7 mmHg) and YM (10.8 ± 5.7 mmHg). OW (–20.2 ± 7.2%) had greater (P < 0.05) decreases in QL compared with YW (–9.4 ± 10.2%), but no significant differences were present between OM (–22.8 ± 9.7%) and YM (–22.7 ± 11.3%) during the 65% IRBT. The 65% IRBT led to greater (P < 0.05) increases in LVR in OW (48.2 ± 25.5%) compared with YW (19.7 ± 15.0%), but no differences (P > 0.05) existed among OM (54.4 ± ...

Source: AJP: Heart and Circulatory Physiology - May 1, 2017 Category: Cardiology Authors: Smith, J. R., Alexander, A. M., Hammer, S. M., Didier, K. D., Kurti, S. P., Broxterman, R. M., Barstow, T. J., Harms, C. A. Tags: RESEARCH ARTICLE Source Type: research