Abstract: Original research Lizelle Steenkamp,1 Robin Terence Saggers ‍ ‍,2,3 Rossella Bandini,4 Saverio Stranges,5,6 Yun-­Hee Choi,7 Jane S Thornton ‍ ‍,8 Simon Hendrie,9 Deepak Patel,1 Shannon Rabinowitz,9 Jon Patricios ‍ ‍2 ►► Additional supplemental material is published online only. To view, please visit the journal online (http://d​ x.​doi.​ org/1​ 0.​1136/b​ jsports-​2021-​ 105159). For numbered affiliations see end of article. Correspondence to Professor Jon Patricios, Wits Sport and Health (WiSH), School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg-­Braamfontein, South Africa; ​jpat@​mweb.c​ o.​za Accepted 21 January 2022 © Author(s) (or their employer(s)) 2022. Re-­use permitted under CC BY-­NC. No commercial re-­use. See rights and permissions. Published by BMJ. To cite: Steenkamp L, Saggers RT, Bandini R, et al. Br J Sports Med Epub ahead of print: [please include Day Month Year]. doi:10.1136/ bjsports-2021-105159 ABSTRACT Objective To determine the association between directly measured physical activity and hospitalisation, intensive care unit (ICU) admission, ventilation and mortality rates in patients with a confirmed diagnosis of COVID-­19. Methods Directly measured physical activity data from 65 361 adult patients with a COVID-­19 diagnosis from 19 March 2020 to 30 June 2021, were grouped by activity level: low (<60 min/week), moderate (60–149 min/week) and high activity (≥150 min/week). The association of physical activity levels and the risk of adverse outcomes was analysed using modified Poisson regression. We accounted for demographics and comorbidities including conditions known to influence COVID-­19 outcomes, as well as patient complexity as measured by the Johns Hopkins Adjusted Clinical Group system. The regression approach was further validated with a Bayesian network model built off a directed acyclic graph. Results High physical activity was associated with lower rates of hospitalisation (risk ratio, RR 0.66, 95% CI 0.63 to 0.70), ICU admission (RR 0.59, 95% CI 0.52 to 0.66), ventilation (RR 0.55, 95% CI 0.47 to 0.64) and death (RR 0.58, 95% CI 0.50 to 0.68) due to COVID-­19 than those who engaged in low physical activity. Moderate physical activity also was associated with lower rates of hospitalisation (RR 0.87, 95% CI 0.82 to 0.91), admission to ICU (RR 0.80, 95% CI 0.71 to 0.89), ventilation (RR 0.73, 95% CI 0.62 to 0.84) and death (RR 0.79, 95% CI 0.69 to 0.91). Conclusions Adults with high and moderate physical activity levels had significantly better outcomes than those with low activity when contracting COVID-­19. The apparent protective effects of regular physical activity extended to those with concomitant chronic medical conditions.