Higher cardiorespiratory fitness linked to lower COVID-19 hospitalization risk, but not SARS-CoV-2 infection, in a large population cohort.
Cardiorespiratory Fitness Linked to Lower COVID-19 Hospitalization Risk
CARDIORESPIRATORY FITNESS is associated with a significantly lower risk of COVID-19 related hospitalization, although it does not appear to influence the likelihood of SARS-CoV-2 infection, according to a large cohort study of Norwegian adults.
Physical activity has previously been associated with improved outcomes in respiratory infections. However, the relationship between cardiorespiratory fitness and the risk of infection or severe illness from coronavirus disease 2019 has remained unclear. Researchers therefore examined whether pre-pandemic fitness levels and leisure time physical activity were linked to the risk of SARS-CoV-2 infection and COVID-19 related hospitalization.
Cardiorespiratory Fitness and Infection Risk
The study cohort included 48,821 adults participating in the Trøndelag Health Study (the HUNT Study). Pre-pandemic data on estimated cardiorespiratory fitness and leisure-time physical activity collected between 2017 and 2019 were linked with national COVID-19 registries covering the period from February 2020 through September 2022.
Estimated cardiorespiratory fitness was categorized into sex and age specific quintiles based on peak oxygen uptake measured in milliliters per kilogram per minute. Leisure time physical activity was classified according to metabolic equivalent hours per week: inactive (0–3.5 metabolic equivalent hours per week), insufficiently active (>3.5–7.5 metabolic equivalent hours per week), and sufficiently active (>7.5 metabolic equivalent hours per week). Poisson regression models were used to estimate incidence rate ratios and 95% confidence intervals for associations between estimated cardiorespiratory fitness, leisure time physical activity, and the outcomes of SARS-CoV-2 infection and COVID-19 related hospitalization.
The mean age of participants was 53.6 years (SD, 16.8), and 53.9% were women. Over a mean follow-up period of 2.6 years, researchers recorded 5,991 SARS-CoV-2 infections and 218 COVID-19–related hospitalizations. Neither cardiorespiratory fitness levels nor leisure-time physical activity categories were associated with the risk of SARS-CoV-2 infection.
Cardiorespiratory Fitness and Hospitalization Risk
In contrast, higher levels of cardiorespiratory fitness were associated with substantially lower risk of hospitalization. Adults in the highest fitness quintile had a reduced risk of COVID-19 related hospitalization compared with those in the lowest quintile (incidence rate ratio: 0.54; 95% CI: 0.34–0.86).
Similarly, adults who were sufficiently active prior to the pandemic had a lower risk of hospitalization compared with inactive adults (incidence rate ratio: 0.60; 95% CI: 0.47–0.83).
Implications For Population Health
These findings indicate that while cardiorespiratory fitness and leisure time physical activity may not influence the risk of contracting SARS-CoV-2, higher fitness levels before the pandemic were associated with reduced risk of severe disease requiring hospital care.
The results suggest that maintaining cardiorespiratory fitness and regular physical activity could contribute to improved resilience against severe COVID-19 outcomes.
Reference
Eriksen EA et al. Cardiorespiratory fitness and physical activity and risk of SARS-CoV-2 and COVID-19 hospitalization: the HUNT study. BMC Infect Dis. 2026;DOI:10.1186/s12879-026-12684-1;26:396.
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