Palmar Cooling as a Thermoregulatory Intervention: Mechanistic Basis and Implications for Exercise and Clinical Applications.

During exercise, rising metabolic heat production creates competition for blood flow between skeletal muscle and the cutaneous vasculature. The resulting redistribution elevates cardiovascular (CV) strain and accelerates fatigue, particularly during environmental heat stress or in individuals with impaired thermoregulatory capacity. Strategies that enhance heat dissipation without further burdening CV function may therefore improve exercise tolerance. Palmar cooling (PC) is an intervention that targets the glabrous skin of the hands, where dense arteriovenous anastomoses facilitate high-flow, low-resistance blood flow and efficient convective heat exchange, thereby augmenting systemic heat dissipation through the peripheral circulation. Evidence in healthy and athletic populations suggests that PC can decrease thermal strain while improving endurance capacity, resistance training volume, and perceptual responses when applied under meaningful heat stress, although current findings remain heterogeneous. Given age- and disease-related reductions in thermoregulatory and CV reserve, PC may have translational relevance for enhancing exercise tolerance during rehabilitation, reducing heat-related illness risk, and supporting individuals with cardiopulmonary disease. Improved within-session tolerability may, in turn, facilitate greater cumulative training stimulus and adherence, with potential downstream benefits for overall exercise capacity. This narrative review discusses the thermoregulatory, CV, and exercise physiology underlying PC, evaluates the current evidence, and outlines future directions to support clinical translation.