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 0.5A degrees 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 (similar to 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 x age group). When standing and heated, wearing compression leggings lowered TPR in older and younger participants (similar to 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.