Key result
Older women exhibited a greater inspiratory muscle metaboreflex, with larger increases in mean arterial pressure (15.9 vs 6.9 mmHg) compared with young women, whereas men showed no age differences.
Why the study?
Do age and sex affect the cardiovascular consequences (MAP, limb blood flow, limb vascular resistance) of the inspiratory muscle metaboreflex?
Cross-Sectional (n=32)
Do age and sex affect the cardiovascular consequences (MAP, limb blood flow, limb vascular resistance) of the inspiratory muscle metaboreflex?
Absolute Event Rate: 15.9% vs 6.9%
p-value: p=<0.05
Older women exhibit an exaggerated inspiratory muscle metaboreflex compared to young women, eliminating the sex differences that are present in younger adults.
May heighten hemodynamic burden during inspiratory loading in older women; hypothesis-generating for sex-specific aging effects on metaboreflex.
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 (Q̇ L ) 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, Q̇ L 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 Q̇ L 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 ± 17.8%) and YM (47.1 ± 23.3%). No significant differences were present in MAP, Q̇ L , or LVR between OM and OW. These data suggest that OW exhibit a greater inspiratory muscle metaboreflex compared with YW, whereas no differences between OM and YM existed. Finally, sex differences in the inspiratory muscle metaboreflex are not present in older adults. NEW & NOTEWORTHY Premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with young men; however, it is unknown whether these sex differences are present in older adults. Older women exhibited a greater inspiratory muscle metaboreflex compared with premenopausal women, whereas no differences were present between older and younger men.
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Smith et al. (2017) conducted a cross-sectional in Healthy adults (n=32). Inspiratory resistive breathing tasks (IRBTs) vs. Young adults / 2% IRBT was evaluated on Increase in mean arterial pressure (MAP) during 65% IRBT in older vs young women (p=<0.05). Older women exhibited a greater inspiratory muscle metaboreflex, with larger increases in mean arterial pressure (15.9 vs 6.9 mmHg) compared with young women, whereas men showed no age differences.
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