Thermoregulation is Not Impaired in Breast Cancer Survivors During Moderate Intensity Exercise Performed in Warm and Hot Environments: International Conference on the Physiology and Pharmacology of Temperature Regulation, Virtual

Introduction: Breast cancer survivors (BCS) regularly report hot flashes; suggestive of altered thermoregulatory control. However, little is known about how this population responds when exercising and when under heat stress. Question addressed: Whether female BCS are chal-lenged from a thermoregulatory impairment during exercise under heat stress compared to healthy females. Methods: Following University of Brighton’s ethical approval, 9 BCS and 12 control females matched for age (54±7years), body surface area (1.76±0.11m2) and body fat percentage (30.9±3.8%) completed a warm (25°C, 50% relative humidity, RH) and hot (35°C, 50%RH) trial in a repeated-measures design. Trials consisted of 30-minutes of rest, 30-minutes of walking at 4 metabolic equivalents, and a 6-minute walk test (6MWT). Core temperature (Tre), skin temperature (Tskin), and heart rate (HR) were recorded throughout, and whole-body sweat rate (WBSR) calculated. Distance covered during the 6MWT was used as a measure of functional performance. Results: Tre was ~0.25°C higher during exercise in 35°C vs. 25°C (p=0.0002), with no differences observed between groups for either condition (p=0.245). Simi-larly, skin temperature was ~3.8°C higher in 35°C vs. 25°C (p<0.001), but not different between groups (p=0.952). HR was ~12beats.min-1 higher in 35°C vs. 25°C (p=0.023), with no differ-ences between groups (p=0.84). WBSR was ~0.4L.hr-1 greater after 35°C vs. 25°C (p<0.001), with no difference between groups (p=0.08). Both groups covered a greater 6MWT distance in 25°C vs. 35°C (by ~0.02km; p=0.003). Nevertheless, the control group covered more distance than BCS, regardless of environmental temperature (by ~0.04km, p=0.03). Conclusion: Thermoregulation was not compromised in BCS compared to healthy females during moderate-intensity exercise under heat stress. However, self-paced exer-cise performance was reduced for BCS. Future research investigating whether BCS heat-related symptoms (e.g. hot flashes) influence functional exercise performance under heat stress is re-quired.