High fitness levels, frequent sauna bathing and risk of pneumonia in a cohort study: Are there potential implications for COVID-19?

Setor K Kunutsor*, Jari A Laukkanen

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Background: There is ongoing debate on a potential protective role of habitual physical activity and passive heat therapy on the risk of COVID-19, a respiratory infectious disease which can manifest as severe pneumonia. To explore these putative roles, we evaluated the independent and joint associations of cardiorespiratory fitness (CRF) and frequency of sauna bathing (FSB) with pneumonia risk in a prospective cohort study of 2,275 men aged 42-61 years at recruitment. Material and Methods: Objectively measured CRF and self-reported sauna bathing habits were assessed at baseline. CRF was categorized as low and high (median cutoffs) and FSB as low and high (defined as ≤ 1 and 2-7 sessions/week respectively). Multivariable-adjusted hazard ratios (HRs) with confidence intervals (CIs) were calculated for incident pneumonia. Results: During a median follow-up of 26.6 years, 529 cases of pneumonia occurred. Comparing high vs low CRF, the multivariable-adjusted HR (95% CIs) for pneumonia was 0.75 (0.61-0.91). Comparing high vs low FSB, the corresponding HR was 0.81 (0.68-0.97). Compared to men with low CRF & low FSB, the multivariable-adjusted HRs of pneumonia for the following groups: high CRF & low FSB; low CRF & high FSB; and high CRF & high FSB were 0.88 (0.65-1.20), 0.89 (0.71-1.13), and 0.62 (0.48-0.80) respectively. Conclusions: In a general male Caucasian population, a combination of high fitness levels and frequent sauna baths is associated with a substantially lowered risk of future pneumonia compared with each modality alone. The implications of these findings in altering COVID-19 disease or its severity deserves study.
Original languageEnglish
Article numbere13490
Number of pages6
JournalEuropean Journal of Clinical Investigation
Issue number3
Early online date10 Jan 2021
Publication statusPublished - 1 Mar 2021

Bibliographical note

Funding Information:
We thank the staff of the Kuopio Research Institute of Exercise Medicine and the Research Institute of Public Health and the University of Eastern Finland, Kuopio, Finland, for the data collection in the study. This work was supported by the Finnish Foundation for Cardiovascular Research, Helsinki, Finland. SKK is funded by the NIHR Biomedical Research Centre at University Hospitals Bristol and Weston NHS Foundation Trust and the University of Bristol (BRC‐1215‐20011). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

Publisher Copyright:
© 2021 The Authors. European Journal of Clinical Investigation published by John Wiley & Sons Ltd on behalf of Stichting European Society for Clinical Investigation Journal Foundation.

Structured keywords

  • Covid19


  • cardiorespiratory fitness
  • COVID-19
  • pneumonia
  • sauna


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