Population aging, high prevalence of non-communicable diseases, physical inactivity, and rising global temperatures are some of the most pressing issues in public health of the current century. Such trends suggest that individuals increasingly less equipped to tolerate heat will be increasingly exposed to it, which from a public health perspective is alarming. Nonetheless, future impacts of extreme heat events will depend not only on the magnitude of climate change, but on our ability to adapt by becoming less sensitive and vulnerable. Although physical activity's role in mitigating climate change has received attention, its potential contribution to climate change adaptation and resilience remains largely unaddressed. Accordingly, in this viewpoint, we discuss how regular physical activity throughout life could have an important contribution to adapting to rising global temperatures, allowing to be better equipped to cope with heat-related health hazards and increasing individual and community resilience. This viewpoint constitutes a call for more research into the contribution that physical activity can have in adapting to rising global temperatures and, more broadly, to climate change.

Understanding the impact of stressors on the rating of perceived exertion (RPE) is relevant from a performance and exercise adherence/participation standpoint. Athletes and recreationally active individuals dehydrate during exercise. No attempt has been made to systematically determine the impact of exercise-induced dehydration (EID) on RPE. The present meta-analysis aimed to determine the effect of EID on RPE during endurance exercise and examine the moderating effect of potential confounders. Performed on raw RPE values using random-effects models weighted mean effect summaries and meta-regressions with robust standard errors, and with a practical meaningful effect set at 1 point difference between euhydration (EUH) and EID. Only controlled crossover studies measuring RPE with a Borg scale in healthy adults performing ≥30 min of continuous endurance exercise while dehydrating or drinking to maintain EUH were included. Sixteen studies were included, representing 147 individuals. Mean body mass loss with EUH was 0.5 ± 0.4%, compared to 2.3 ± 0.5% with EID (range 1.7–3.1%). Within an EID of 0.5–3% body mass, a maximum difference in RPE of 0.81 points (95% CI: 0.36–1.27) was observed between conditions. A meta-regression revealed that RPE increases by 0.21 points for each 1% increase in EID (95% CI: 0.12–0.31). Humidity, ambient temperature and aerobic capacity did not alter the relationship between EID and RPE. Therefore, the effect of EID on RPE is unlikely to be practically meaningful until a body mass loss of at least 3%.

Epidemiological studies have observed that female sex is associated with a greater risk of adverse health outcomes during heat extremes. It remains unclear if sex-related differences in autonomic temperature regulation contribute to these observations. This narrative review article provides an overview of studies that compared autonomic temperature regulation during heat stress between males and females across the lifespan. Our literature search focused on studies that investigated components of heat loss thermoeffector loops and/or that accounted for confounding differences in body morphology and metabolic heat production between males and females. Guided by this framework, we present studies that compared autonomic temperature regulation between males and females during childhood to adolescence, adulthood, middle-age, and older age. The review highlights that few studies have specifically studied sex-related differences in autonomic temperature regulation during heat stress. Most studies have focused on thermoeffector output and core temperature. In contrast, little is known regarding thermoafferent signalling, central integration of thermoafferent feedback, thermoefferent signalling and thermoeffector organ structure and function. Additional research is needed to understand how biological sex modulates autonomic temperature regulation during heat stress and how any sex-related difference may contribute to the greater health risks observed in females during heat extremes.

Planet Earth is warming at an unprecedented rate and our future is now assured to be shaped by the consequences of more frequent hot days and extreme heat. Humans will need to adapt both behaviorally and physiologically to thrive in a hotter climate. From a physiological perspective, countless studies have shown that human heat acclimation increases thermoeffector output (i.e., sweating and skin blood flow) and lowers cardiovascular strain (i.e., heart rate) during heat stress. However, the mechanisms mediating these adaptations remain understudied. Furthermore, several possible benefits of heat acclimation for other systems and functions involved in maintaining health and performance during heat stress remain to be elucidated. This review summarizes recent advances in human heat acclimation, with emphasis on recent studies that (1) advanced our understanding of the mechanisms mediating improved thermoeffector output and (2) investigated adaptations that go beyond those classically associated with heat acclimation. We highlight that these studies have contributed to a better understanding of the integrated physiological responses underlying human heat acclimation while leaving key unanswered questions that will need to be addressed in the future.