No independent associations between physical activity and clinical outcomes among hospitalized patients with moderate to severe COVID-19

BACKGROUND: Regular physical activity (PA) has been postulated to improve, or at least maintain, immunity across the life span. However, the link between physical (in)activity and coronavirus disease 2019 (COVID-19) remains to be established. This small-scale prospective cohort study is nested within a randomized controlled trial aimed to investigate the possible associations between PA levels and clinical outcomes among hospitalized patients with moderate to severe COVID-19. METHODS: Hospitalized patients with COVID-19 (mean age: 54.9 years) were recruited from the Clinical Hospital of the School of Medicine of the University of Sao Paulo (a quaternary referral teaching hospital) and from Ibirapuera Field Hospital, both located in Sao Paulo, Brazil. PA level was assessed using the Baecke Questionnaire of Habitual Physical Activity. The primary outcome was hospital length of stay. The secondary outcomes were mortality, admission to the intensive care unit (ICU), and mechanical ventilation requirement. RESULTS: The median hospital length of stay was 7.0 ± 4.0 days, median ± IQR; 3.3% of patients died, 13.8% were admitted to the ICU, and 8.6% required mechanical ventilation. Adjusted linear regression models showed that PA indices were not associated with hospital length of stay (work index: β = –0.57 (95% confidence interval (95%CI): –1.80 to 0.65), p = 0.355; sport index: β = 0.43 (95%CI: –0.94 to 1.80), p = 0.536; leisure-time index: β = 1.18 (95%CI: –0.22 to 2.59), p = 0.099; and total activity index: β = 0.20 (95%CI: –0.48 to 0.87), p = 0.563). None of the PA indices were associated with mortality, admission to the ICU, or mechanical ventilation requirement (all p > 0.050). CONCLUSION: Among hospitalized patients with COVID-19, PA did not independently associate with hospital length of stay or any other clinically relevant outcomes. These findings should be interpreted as meaning that, among already hospitalized patients with more severe forms of COVID-19, being active is a potential protective factor likely outweighed by a cluster of comorbidities (e.g., type 2 diabetes, hypertension, weight excess) and older age, suggesting that the benefit of PA against the worsening of COVID-19 may vary across stages of the disease.