The sauna and the cardiovascular system

Objective: To review the physiology, practical use, and cardiovascular safety considerations of sauna bathing. This narrative review summarized thermal responses, autonomic changes, hemodynamic load, sweat-related fluid loss, and common safety issues relevant to healthy adults and patients with cardiovascular disease. The authors described how sauna exposure transiently increases heart rate and cardiac output while promoting vasodilation and relaxation, potentially producing effects similar to light-to-moderate exercise in some respects. The review also discussed traditional use patterns, tolerance limits, and the importance of hydration and avoidance in unstable medical states. Although the evidence base at the time was largely physiologic and observational, the review framed sauna as a generally safe practice for appropriately selected individuals. It emphasized that acute tolerance is influenced by heat intensity, duration, and comorbid disease burden. The article became a foundational reference for later epidemiologic studies exploring long-term associations between sauna use and cardiovascular outcomes.