Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trial.

Earric Lee, Iiris Kolunsarka, Joel Kostensalo, Juha P Ahtiainen, Eero A Haapala, Peter Willeit, Setor K Kunutsor, Jari A Laukkanen

Journal: American journal of physiology. Regulatory, integrative and comparative physiology 2022;323(3):R289-R299

PMID: 35785965

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Plain Language Summary

Physical activity and exercise training are well-documented strategies to prevent ailments and various diseases. However, unlike exercise, heat therapy and the health benefits of Finnish sauna bathing are still not well understood, despite its increasing use throughout the world. The aim of this study was to compare the cardiovascular adaptations of regular exercise alone (EXE) to regular exercise and sauna bathing (EXS), with a sedentary control (CON) group. This study is an 8-week multi-arm randomised controlled trial. Forty-eight participants (females n= 42) were randomly assigned into the EXS, EXE, or the CON group. Results show that regular exercise using the recommended guidelines three times a week, for 50 minutes each time, can effectively improve cardiorespiratory fitness (CRF) and body composition. The addition of a regular 15-minute typical Finnish sauna after exercise supplemented the gains in CRF, reductions in systolic blood pressure, and lowered total cholesterol levels considerably. Authors conclude that sauna bathing is a safe and simple lifestyle modification and steps should be taken to make it more accessible worldwide. Thus, future studies should seek to understand the optimal exposure durations, frequencies, modalities, and temperatures for various beneficial adaptations.

Abstract

Regular exercise and sauna bathing have each been shown to improve cardiovascular function in clinical populations. However, experimental data on the cardiovascular adaptations to regular exercise in conjunction with sauna bathing in the general population are lacking. Therefore, we compared the effects of exercise and sauna bathing to regular exercise using a multi-arm randomized controlled trial. Participants ( = 47) aged 49 ± 9 with low physical activity levels and at least one traditional cardiovascular disease (CVD) risk factor were randomly assigned (1:1:1) to guideline-based regular exercise and 15-min postexercise sauna (EXS), guideline-based regular exercise (EXE), or control (CON) for 8 wk. The primary outcomes were blood pressure (BP) and cardiorespiratory fitness (CRF) Secondary outcomes included fat mass, total cholesterol levels, and arterial stiffness. EXE had a greater change in CRF (+6.2 mL/kg/min; 95% CI, +4.2 to +8.3 mL/kg/min) and fat mass but no differences in BP when compared with CON. EXS displayed greater change in CRF (+2.7 mL/kg/min; 95% CI, +0.2 to +5.3 mL/kg/min), lower systolic BP (-8.0 mmHg; 95% CI, -14.6 to -1.4 mmHg), and lower total cholesterol levels compared with EXE. Regular exercise improved CRF and body composition in sedentary adults with CVD risk factors. However, when combined with exercise, sauna bathing demonstrated a substantially supplementary effect on CRF, systolic BP, and total cholesterol levels. Sauna bathing is a valuable lifestyle tool that complements exercise for improving CRF and decreasing systolic BP. Future research should focus on the duration and frequency of exposure to ascertain the dose-response relationship.

Address: Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.; Natural Resources Institute Finland (Luke), Joensuu, Finland.; Institute of Biomedicine, School of Medicine, University of Eastern Finland, Kuopio, Finland.; Clinical Epidemiology Team, Medical University of Innsbruck, Innsbruck, Austria.; Department of Public Health and Primary Care, University of Cambridge, Cambridge, United Kingdom.; National Institute for Health Research Bristol Biomedical Research Centre, University Hospitals Bristol and Weston National Health Service Foundation Trust and the University of Bristol, Bristol, United Kingdom.; Translational Health Sciences, Bristol Medical School, University of Bristol, Southmead Hospital, Bristol, United Kingdom.; Central Finland Central Hospital, Department of Internal Medicine, Jyväskylä, Finland.; Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.

DOI: 10.1152/ajpregu.00076.2022