We hypothesized that, compared to 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 (Q̇L), but 3) no sex differences would be present in older adults. Sixteen young (8 men (YM), 8 women (YW); 18-24 yrs) and older (8 men (OM), 8 women (OW); 60-73 yrs) adults performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths min-1 with a 50% duty cycle. At baseline and during the IRBTs, MAP was measured via automated oscillometry, Q̇L was determined via Doppler ultrasound, and LVR was calculated. The 65% IRBT led to significantly greater increases in MAP in OW (15.9±8.1mmHg) compared to YW (6.9±1.4mmHg), but not (p>0.05) between OM (12.3±5.7mmHg) and YM (10.8±5.7 mmHg). OW (-20.2±7.2%) had greater (p<0.05) decreases in Q̇L compared to 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 to 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, Q̇L, or LVR between OM and OW. These data suggest OW exhibit a greater inspiratory muscle metaboreflex compared to YW, while no differences between OM and YM existed. Lastly, sex differences in the inspiratory muscle metaboreflex are not present in older adults.
- blood pressure
- limb vascular resistance
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology