Compression leggings modestly affect cardiovascular but not cerebrovascular responses to heat and orthostatic stress in young and older adults

Abstract

We tested the hypothesis that wearing commercially available compression leggings would attenuate postural reductions in mean arterial blood pressure (MAP) and cerebral perfusion during heat stress, particularly in older adults. Six older (70 years±4) and six younger (29 years±4) males were heated (esophageal temperature raised 0.5°C) in a water-perfused suit whilst wearing compression or control leggings (>1 week apart, randomized order). Blood flow velocity in the middle cerebral artery (MCAv), blood pressure (photoplethysmography), total peripheral resistance (TPR; ModelFlow) and the partial pressure of end-tidal carbon dioxide were measured continuously before and during 3-min standing in each thermal state. When supine, compression leggings did not change any cardiorespiratory variables in either age group or thermal condition (P>0.05). Upon standing, wearing compression leggings delayed (~15%; P=0.044) the maximal drop (nadir) in MAP irrespective of age or thermal condition. During the last minute of standing, wearing compression leggings in normothermia increased TPR (+16%) in older participants but dropped TPR (−8%) in younger participants (P=0.004 compression×age group). When standing and heated, wearing compression leggings lowered TPR in older and younger participants (~43%; P<0.01) without changing MAP or MCAv (P>0.05). In older adults, when standing, compression leggings maintained MAP by elevating TPR. In contrast, under combined heat and orthostatic stress, wearing compression leggings dropped TPR in both older and younger adults, though MAP and MCAv were maintained.

Knee‐high compression socks minimize head‐up tilt‐induced cerebral and cardiovascular responses following dynamic exercise

“…This may allow CS to have a greater net effect on blood volume and pooling in the lower extremities. A similar hypothesis has been proposed by Lucas et al after examining the effect of compression leggings on young and elderly individuals subjected to combined heat and orthostatic stress. The authors found that under combined heat and orthostatic stress, compression leggings maintained MAP by passively reducing the venous pooling in the lower limbs and increasing TPR.…”

Healthy aging does not compromise the augmentation of cardiac function during heat stress

“…This raises an interesting question: What is limiting the increase in cardiac output in aged adults during heat stress, despite an augmentation of cardiac function? In this study, the attenuated increase in cardiac output was primarily driven by an attenuated increase in heart rate, consistent with similar observations for this age group (12,14,21,22). Increases in heart rate during heat stress occur mainly through changes in cardiac parasympathetic/sympathetic neural activity and to a lesser extent because of the direct effect of temperature on the heart (13,17).…”

“…Nonetheless, aged adults are unable to maintain stroke volume during heat exposure (25,26). Importantly, this inability to maintain stroke volume fully accounts for the attenuated increase in cardiac output, as heart rate responses are generallythough not always (12,14,21,22)-similar to the young (23,25,26). These results suggest that although Doppler-derived indexes of systolic function are augmented during heat stress in aged adults (23), cardiac contractility may not increase sufficiently to maintain stroke volume during heat-induced reductions in cardiac filling pressures.…”

Cerebral Vascular Control and Metabolism in Heat Stress

“…It was shown that, in addition to marked lowering of cerebral perfusion (as indexed by MCAv) with ageing, there are further age-related reductions in MCAv and slower corrections of MAP with resuming the upright posture in both normothermic and passive heat conditions (269); however, these changes were otherwise asymptomatic to represent a physiologically acceptable insult, at least with mild elevations (0.5 • C rise in esophageal temperature) in body temperature. The utility of compression garments to attenuate postural reductions in mean arterial blood pressure and cerebral perfusion during heat stress during supine rest and orthostasis was minimal with a +0.5 • C increase in esophageal temperature (268).…”

“…In fact, only two studies to date have examined such interactions in both young (29 ± 4 years) and otherwise healthy elderly participants (70 ± 4 years) (268,269). It was shown that, in addition to marked lowering of cerebral perfusion (as indexed by MCAv) with ageing, there are further age-related reductions in MCAv and slower corrections of MAP with resuming the upright posture in both normothermic and passive heat conditions (269); however, these changes were otherwise asymptomatic to represent a physiologically acceptable insult, at least with mild elevations (0.5 • C rise in esophageal temperature) in body temperature.…”