Obesity Increases Cardiovascular Strain During Passive Whole‐Body Heat Stress in Middle‐Aged Women

Objective Heat‐related mortality is greater in middle‐aged and older women, compared with age‐matched men, and in those with obesity, although the causes are unclear. Methods Thermoregulatory and cardiovascular responses were assessed in ( n = 10 per group) young women (21 ± 2 years), middle‐aged women without obesity (−OB; 55 ± 6 years), and middle‐aged women with obesity (+OB; 55 ± 4 years) during whole‐body heat stress until a change in core temperature (Δ T c ) = 1°C. Cutaneous vasodilation (laser‐Doppler flowmetry) and whole‐body sweat rate (sweat loss/body surface area/time) were measured as indices of thermoregulatory function. Heart rate and blood pressure were measured, and rate pressure product (RPP = heart rate × systolic blood pressure) was calculated as an index of cardiovascular strain. Results The magnitude of the peak cutaneous vasodilation response was not different among the groups ( p ≥ 0.21), but thermosensitivity was higher in Young compared with +OB and −OB ( p ≤ 0.03). Although there were no baseline differences in RPP ( p ≥ 0.67), end‐heating RPP was higher in +OB compared with −OB and Young ( p ≤ 0.008). Further, body fat percentage was related to peak RPP ( p = 0.03, R 2 = 0.24) in middle‐aged women. Conclusions Increased adiposity may contribute to greater cardiovascular risk during extreme heat exposure in middle‐aged women.