Abstract: ORIGINAL ARTICLE Association Between AccelerometerAssessed Physical Activity and Severity of COVID-19 in UK Biobank Alex V. Rowlands, PhD; Paddy C. Dempsey, PhD; Clare Gillies, PhD; David E. Kloecker, MPhil; Cameron Razieh, PhD; Yogini Chudasama, PhD; Nazrul Islam, PhD; Francesco Zaccardi, PhD; Claire Lawson, PhD; Tom Norris, PhD; Melanie J. Davies, MD; Kamlesh Khunti, PhD; and Tom Yates, PhD Abstract Objective: To quantify the association between accelerometer-assessed physical activity and coronavirus disease 2019 (COVID-19) outcomes. Methods: Data from 82,253 UK Biobank participants with accelerometer data (measured 2013-2015), complete covariate data, and linked COVID-19 data from March 16, 2020, to March 16, 2021, were included. Two outcomes were investigated: severe COVID-19 (positive test result from in-hospital setting or COVID-19 as primary cause of death) and nonsevere COVID-19 (positive test result from community setting). Logistic regressions were used to assess associations with moderate to vigorous physical activity (MVPA), total activity, and intensity gradient. A higher intensity gradient indicates a higher proportion of vigorous activity. Results: Average MVPA was 48.1 (32.7) min/d. Physical activity was associated with lower odds of severe COVID-19 (adjusted odds ratio per standard deviation increase: MVPA, 0.75 [95% CI, 0.67 to 0.85]; total, 0.83 [0.74 to 0.92]; intensity, 0.77 [0.70 to 0.86]), with stronger associations in women (MVPA, 0.63 [0.52 to 0.77]; total, 0.76 [0.64 to 0.90]; intensity, 0.63 [0.53 to 0.74]) than in men (MVPA, 0.84 [0.73 to 0.97]; total, 0.88 [0.77 to 1.01]; intensity, 0.88 [0.77 to 1.00]). In contrast, when mutually adjusted, total activity was associated with higher odds of a nonsevere infection (1.10 [1.04 to 1.16]), whereas the intensity gradient was associated with lower odds (0.91 [0.86 to 0.97]). Conclusion: Odds of severe COVID-19 were approximately 25% lower per standard deviation (w30 min/ d) MVPA. A greater proportion of vigorous activity was associated with lower odds of severe and nonsevere infections. The association between total activity and higher odds of a nonsevere infection may be through greater community engagement and thus more exposure to the virus. Results support calls for public health messaging highlighting the potential of MVPA for reducing the odds of severe COVID-19. ª 2021 THE AUTHORS. Published by Elsevier Inc on behalf of Mayo Foundation for Medical Education and Research. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) n Mayo Clin Proc Inn Qual Out 2021;5(6):997-1007 P oor outcomes from coronavirus disease 2019 (COVID-19) are more likely in people who are older,1 are more deprived,2 have comorbidities,3 or are from ethnic minority populations.4 As with chronic disease, research suggests that risk factors related to health behaviors, such as obesity5 and slow walking pace,6 also have a negative impact on COVID-19 outcomes. Physical activity is a modifiable health behavior that may mitigate the risks of COVID-19.7 This could occur through reductions in chronic inflammation8,9 or cardiometabolic risk factors,10 which are associated with an increased risk of COVID-19,11 or through enhanced immunity.7 In the early months of the pandemic (up to July 2020), we reported initial observations from Biobank data,12 which was suggestive evidence for lower odds (up to 20%) of severe COVID-19 per 30 minutes of daily..