Article Text

Original research
Fitness, strength and severity of COVID-19: a prospective register study of 1 559 187 Swedish conscripts
  1. Agnes af Geijerstam1,
  2. Kirsten Mehlig1,
  3. Mats Börjesson2,3,
  4. Josefina Robertson1,4,
  5. Jenny Nyberg5,
  6. Martin Adiels1,2,
  7. Annika Rosengren2,6,
  8. Maria Åberg1,7,
  9. Lauren Lissner1
  1. 1School of Public Health and Community Medicine, Institute of Medicine, University of Gothenburg Sahlgrenska Academy, Goteborg, Sweden
  2. 2Department of Molecular and Clinical Medicine, University of Gothenburg Sahlgrenska Academy, Goteborg, Sweden
  3. 3Center for Health and Performance, University of Gothenburg, Goteborg, Västra Götaland, Sweden
  4. 4Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg Sahlgrenska Academy, Goteborg, Sweden
  5. 5Section for Clinical Neuroscience, Institute of Neuroscience and Physiology, University of Gothenburg Sahlgrenska Academy, Goteborg, Sweden
  6. 6Sahlgrenska University Hospital, Goteborg, Sweden
  7. 7Regionhälsan, Region Västra Götaland, Göteborg, Sweden
  1. Correspondence to Dr Agnes af Geijerstam; agnes.af.geijerstam{at}gu.se

Abstract

Objective To investigate the possible connection between cardiorespiratory fitness (CRF) and muscle strength in early adulthood and severity of COVID-19 later in life.

Design Prospective registry-based cohort study.

Participants 1 559 187 Swedish men, undergoing military conscription between 1968 and 2005 at a mean age of 18.3 (SD 0.73) years.

Main outcome measures Hospitalisation, intensive care or death due to COVID-19 from March to September 2020, in relation to CRF and muscle strength.

Results High CRF in late adolescence and early adulthood had a protective association with severe COVID-19 later in life with OR (95% CI) 0.76 (0.67 to 0.85) for hospitalisation (n=2 006), 0.61 (0.48 to 0.78) for intensive care (n=445) and 0.56 (0.37 to 0.85) for mortality (n=149), compared with the lowest category of CRF. The association remains unchanged when controlled for body mass index (BMI), blood pressure, chronic diseases and parental education level at baseline, and incident cardiovascular disease before 2020. Moreover, lower muscle strength in late adolescence showed a linear association with a higher risk of all three outcomes when controlled for BMI and height.

Conclusions Physical fitness at a young age is associated with severity of COVID-19 many years later. This underscores the necessity to increase the general physical fitness of the population to offer protection against future viral pandemics.

  • COVID-19
  • epidemiology
  • public health

Data availability statement

Data may be obtained from a third party and are not publicly available. The data used in this study is available on request from the Swedish National Board of Health and Welfare, the Swedish intensive care registry and Statistics Sweden.

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Data availability statement

Data may be obtained from a third party and are not publicly available. The data used in this study is available on request from the Swedish National Board of Health and Welfare, the Swedish intensive care registry and Statistics Sweden.

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Footnotes

  • Twitter @agnesafg

  • Contributors LL and MÅ initiated the project. AaG and KM performed all statistical analyses. AaG had main responsibility for writing the article. MB, JR, JN, MA and AR all made substantial contributions to the interpretation of the analyses, the structure and content of the manuscript and have read and approved of the final draft. All authors have agreed to be accountable for all aspects of the work.

  • Funding This work was supported by the EpiLife-Teens Research Program (FORMAS2012-00038), the Swedish ALF-agreement (ALFGBG-720201) and the Swedish Research Council (02508, VRREG 2019-00193, 2020-05792).

  • Disclaimer The funding sources had no role in study design, collection, analysis and interpretation of data, the writing of the report, or the decision to submit the article for publication.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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