Biological sex influences aortic hemodynamic responses to maximal exercise in healthy older adults

Abstract

Aging is associated with stiffening of large elastic arteries resulting in early wave reflection, which increases aortic systolic blood pressure (BP) and left ventricular afterload. These age-related alterations predispose older adults to cardiovascular disease (CVD). Exercise is recommended for reducing CVD risk in older adults, but the acute aortic hemodynamic responses to exercise have not been fully described. We have previously shown that exercise intensity influences acute aortic hemodynamic responses to submaximal exercise in older adults, however, the responses to maximal exercise have not been investigated. In young adults, the influence of maximal exercise on aortic wave characteristics is impacted by sex. Therefore, the objective of this study was to investigate the acute effects of maximal exercise on aortic wave characteristics in healthy older adults and to test the hypothesis that the acute aortic hemodynamic responses to maximal exercise will be influenced by sex. Twenty-two older men and postmenopausal women (66.4±1.0 yrs, mean±SE, 11M/11W) completed the study. Research participants were free of major clinical disease, were not using hormone replacement therapy or participating in endurance exercise training. Aortic wave characteristics were assessed using wave separation analysis (SphygmoCor XCEL) before and immediately after maximal exercise, based on a modified Balke treadmill test. We found that wave reflection, assessed as augmentation index (AIx) at heart rate of 75 bpm (AIx@75), was not different between older men and women prior to maximal exercise ( P=0.2). Following maximal exercise, AIx@75 increased in older men (21.1±2.6 vs. 28.2±2.4 %, pre- vs. post-exercise, P=0.02) and women (27.4±3.3 vs. 33.9±3.2 %, P=0.03), but the response was not influenced by sex ( P=0.9 for sex × time interaction). Aortic systolic and diastolic BP (AoSBP and AoDBP) were not different in older men compared with women prior to maximal exercise ( P≥0.4). In response to maximal exercise, AoSBP and AoDBP significantly increased in older men (AoSBP: 113±3 vs. 118±2 mmHg, P=0.01 and AoDBP: 75±2 vs. 80±2 mmHg, P<0.01), but not in women (AoSBP: 113±4 vs. 113±4 mmHg, P=0.9; P=0.04 for sex × time interaction and AoDBP: 73±2 vs. 74±2 mmHg, P=0.054; P=0.02 for sex × time interaction). In conclusion, sex influences the aortic BP response to maximal exercise, but not the wave reflection response in older adults. This finding suggests that left ventricular afterload remains elevated during recovery from maximal exercise in older men which may differentially expose them to a transient risk of experiencing a cardiac complication. This work was supported by National Institute of Aging grant AG063143. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.