Hydration in the Heat: Physiological Mechanisms and Precision Strategies for Exercise Performance and Health

Rising global temperatures are exposing athletes, workers, and the general population to more frequent and intense thermal stress. Exercise and work in the heat imposes substantial demands on fluid balance, cardiovascular regulation, and thermoregulatory control. Even mild dehydration can compromise endurance performance, cognitive function, and safety, while exacerbating cardiovascular load and thermal strain. Although extensive research has established the detrimental effects of fluid loss, recent evidence underscores the large inter-individual variability in sweat rate, electrolyte composition, and the functional impacts on physiology, psychophysiology, cognition, and heat tolerance. Traditional hydration guidelines that follow a universal approach rarely account for these differences. Advances in wearable technology, biochemistry, and integrative physiology now provide tools to quantify real-time hydration status and personalize fluid replacement strategies. However, further studies are required to define physiologically and psycho-physiologically meaningful thresholds and optimize fluid and electrolyte replacement to preserve performance and health during heat exposure.This Research Topic aims to deepen understanding of hydration mechanisms and strategies that sustain exercise performance, recovery, and well-being under heat stress. It seeks to bridge mechanistic, applied, and translational research to identify determinants of fluid and electrolyte balance, cardiovascular strain, metabolic regulation, and cognitive performance in hot environments. Particular emphasis will be given to individual variability, hydration monitoring methods and technologies, and the physiological basis of “precision hydration.” Contributors are encouraged to explore how personalized fluid replacement, beverage composition, nutritional support, cooling interventions, fitness and experience, and heat acclimation interact to enhance thermal tolerance and reduce risk of heat-related illness. By integrating laboratory, clinical, and field evidence, this collection aims to inform future guidelines and decision-making for athletes, laborers, and other heat-exposed populations across levels of fitness, age, and sex.This Research Topic will focus on studies investigating exercise and environmental heat exposure and will not include descriptive sports studies unconnected to physiological mechanisms. It will primarily consider experimental research addressing the physiological basis of hydration, physical activity, and heat stress, conducted preferably in humans but potentially also animal models. To gather further insights in this integrative area, we welcome articles addressing, but not limited to, the following themes:o Hydration and fluid balance during exercise or work in the heato Electrolyte replacement and sweat composition analysiso Precision and individualized hydration strategieso Cardiovascular and thermoregulatory responses to dehydrationo Hydration effects on fatigue, cognition, recovery, or adaptationo Beverage composition and timing with physiologically relevant concentrationso Combined cooling and hydration interventionso Heat acclimation and adaptation mechanismso Hydration monitoring technologies and validation of wearable sensorso Hydration practices across diverse populations (athletes, workers, military, older adults)Submissions spanning basic, translational, and applied exercise physiology are encouraged. For intervention studies, authors should report pre-exercise hydration status, total fluid volume and timing, beverage composition, ambient conditions, and exercise workload to facilitate data comparison and synthesis. Topic editors: Kazunobu Okazaki, Kei Nagashima, James (Jim) David Cotter Source: https://www.frontiersin.org/research-topics/83366/hydration-in-the-heat-physiological-mechanisms-and-precision-strategies-for-exercise-performance-and-health