Repeated Warm Water Immersion Induces Similar Cerebrovascular Adaptations to 8 Weeks of Moderate-Intensity Exercise Training in Females

Abstract

Exercise training has the potential to enhance cerebrovascular function. Warm water immersion has recently been shown to enhance vascular function including the cerebrovascular response to heating. We suggest that passive heating can be used alternatively to exercise. Our aim was to compare the effects of exercise with warm-water immersion training on cerebrovascular and thermoregulatory function. 18 females (25±5 y) performed 8 weeks of cycling (70% HRmax) or warm water immersion (42°C) for 30 min 3 times per week. Brachial artery flow-mediated dilation (FMD) and peak cardiorespiratory fitness (VO2peak) were measured prior to and following both interventions. A passive heat stress was employed to obtain temperature thresholds (Tb) and sensitivities for sweat rate (SR) and cutaneous vasodilation (CVC). Middle cerebral artery velocity (MCAv) was measured throughout. FMD and VO2peak improved following both interventions (p<0.05). MCAv and cerebrovascular conductance were higher at rest and during passive heating (p<0.001 and <0.001, respectively) following both interventions. SR occurred at a lower Tb following both interventions and SR sensitivity also increased, with a larger increase at the chest (p<0.001) following water immersion. CVC occurred at a lower Tb (p<0.001) following both interventions. Warm water immersion elicits similar cerebrovascular, conduit, and thermoregulatory adaptations compared to a period of moderate-intensity exercise training.