Attenuated aortic blood pressure responses to metaboreflex activation in older adults with dynapenia.

Abstract

Low muscle strength (dynapenia) is a primary characteristic of sarcopenia, the age-related loss of muscle mass and strength or low walking speed. New evidence suggests that muscle strength positively affects blood pressure (BP) responses to exercise. As older adults with lowest handgrip strength also have lowest BP at rest, those with dynapenia may experience attenuated BP responses during physical activity. The purpose of this study was to test the hypothesis that dynapenic older adults would exhibit lower BP response to post-exercise muscle ischemia (PEMI). Brachial and aortic systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP) were measured in older adults (age, 80±5 y) with dynapenia (n=16) and non-dynapenia (n=9) at rest and during PEMI following 2min of isometric handgrip exercise at 30% maximal voluntary contraction. Walking speed was assessed by an 8-foot (2.44m) walk course. Increases in aortic SBP (11±2 vs. 23±6mmHg, p=.03), DBP (6±2 vs.14±4mmHg, p=.04), and MAP (8±1 vs. 17±5mmHg, p=.02) were lower in dynapenic compared to non-dynapenic adults. Aortic MAP (r=0.52, p<.05) response to PEMI was correlated with MVC in dynapenic adults. Gait speed was correlated with aortic DBP response to PEMI (r=0.698, p=.05) in non-dynapenic adults. Our findings indicate that aortic DBP response to muscle metaboreflex activation is attenuated in older adults with dynapenia. Normal aortic DBP response during metaboreflex activation may positively affect walking performance in non-dynapenic older adults.