Effects of Sauna bathing on Exercise Capacity and Muscle Function in HFpEF

Treatment options to improve exercise capacity in heart failure with preserved ejection fraction (HFpEF) are limited. We hypothesized that sauna bathing enhances exercise performance, skeletal muscle function, body composition, and quality of life (QoL) in HFpEF. However, benefits may decline after discontinuation. SAUNA-HFpEF is the first prospective mechanistic, translational pilot study investigating feasibility, safety, and efficacy of supervised sauna bathing in stable HFpEF outpatients.

Participants completed 10 weeks of sauna sessions (60°C, twice weekly), with duration progressively increased from 8 to 15 minutes. Blood pressure and heart rate were monitored three times per session. Assessments were performed at baseline, end of study (after 10 weeks intervention), and 3 months after sauna withdrawal (follow-up), including echocardiography, cardiopulmonary exercise testing, 6-minute walk test (6MWT), quadriceps strength testing, QoL questionnaires (SF-36, HADS, EQ-5D), laboratory testing, and body composition. Skeletal muscle biopsies were collected at baseline and at end of study to explore structural and metabolic mechanisms.

Eighteen patients completed the study with 97% adherence and no adverse events. Peak VO2 and 6MWT improved [(18.2±5.1 to 20.6±5.7 ml/min/kg, p<0.001), 494±95 to 527±111m (p=0.006)], as did anaerobic threshold, quadriceps strength, diastolic function (E/e´), HADS-depression-score, and SF-36 social functioning; p<0.05). At follow-up, peak VO2 and anaerobic threshold declined compared to end of study (p<0.01). Body fat mass decreased continuously. Muscle biopsies showed anabolic/metabolic upregulation and catabolism downregulation.

Sauna bathing was safe, feasible, and improved exercise capacity, body composition, muscle function, and QoL in HFpEF. Benefits diminished after withdrawal. A large multicentre controlled randomized trial is currently being planned.