Sauna Bathing in Competitive Athletes: Benefit or Risk for Respiratory and Immune Function? A Narrative Review

Introduction: Sauna bathing has been investigated for its potential health and recovery effects, but its implications for respiratory and immune function in competitive athletes remain uncertain. Objectives: This narrative review synthesizes current evidence on the respiratory and immunological effects of sauna bathing in competitive athletes, evaluating whether the practice constitutes a benefit or a risk in this population. Materials and methods: A non-systematic literature search was conducted in PubMed, Scopus, and the Cochrane Library during August 2026. Experimental and observational studies, case reports, and review articles available in English or Polish were considered. Findings were synthesized narratively, distinguishing athlete-specific evidence from findings in other populations. No formal risk-of-bias assessment was performed. Results: Sauna exposure can transiently alter circulating leukocytes, serum heat-shock proteins, and selected inflammatory mediators, but these responses do not establish improved immune defense. Related analyses of a Finnish population cohort associate frequent sauna bathing with lower respiratory disease incidence, without demonstrating causality or applicability to competitive athletes. Evidence for improved pulmonary function or prevention of respiratory infection in athletes is insufficient. Heat-acclimation and recovery findings address different outcomes. Potential risks include additional thermal and cardiovascular strain, fluid loss, and airway responses that depend on exposure conditions and individual susceptibility. Conclusions: Sauna bathing may offer respiratory and immune benefits, but supporting evidence is largely indirect and derived from non-athlete populations. These benefits remain unconfirmed in competitive athletes. Controlled athlete-specific studies assessing respiratory symptoms, confirmed infections, immune function, and adverse events are needed to clarify the benefit–risk balance.