Abstract: Review Yasmin Ezzatvar ‍ ‍,1 Robinson Ramírez-­Vélez ‍ ‍,2,3 Mikel Izquierdo ‍ ‍,2,3 Antonio Garcia-­Hermoso ‍ ‍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-​2022-​ 105733). 1 Departamento de Enfermería, Universitat de València, Valencia, Spain 2 Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain 3 CIBER de Fragilidad y Envejecimiento Saludable, Instituto de Salud Carlos III, Madrid, Spain Correspondence to Antonio Garcia-­Hermoso, Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona 31006, Spain; a​ ntonio.​garciah@u​ navarra.​es Accepted 22 June 2022 Watch Video ​bjsm.​bmj.​com © Author(s) (or their employer(s)) 2022. No commercial re-­use. See rights and permissions. Published by BMJ. To cite: Ezzatvar Y, Ramírez-­ Vélez R, Izquierdo M, et al. Br J Sports Med Epub ahead of print: [please include Day Month Year]. doi:10.1136/ bjsports-2022-105733 ABSTRACT Objective To quantify the association between physical activity and risk of SARS-­CoV-­2 infection, COVID-­19-­ associated hospitalisation, severe illness and death due to COVID-­19 in adults. Design A systematic review and meta-­analysis. Data sources Three databases were systematically searched through March 2022. Eligibility criteria for selecting studies Peer-­ reviewed articles reporting the association between regular physical activity and at least one COVID-­19 outcome in adults were included. Risk estimates (ORs, relative risk (RR) ratios or HRs) were extracted and pooled using a random-­effects inverse-­variance model. Results Sixteen studies were included (n=1 853 610). Overall, those who engaged in regular physical activity had a lower risk of infection (RR=0.89; 95% CI 0.84 to 0.95; I2=0%), hospitalisation (RR=0.64; 95% CI 0.54 to 0.76; I2=48.01%), severe COVID-­19 illness (RR=0.66; 95% CI 0.58 to 0.77; I2=50.93%) and COVID-­19-­related death (RR=0.57; 95% CI 0.46 to 0.71; I2=26.63%) as compared with their inactive peers. The results indicated a non-­linear dose–response relationship between physical activity presented in metabolic equivalent of task (MET)-­min per week and severe COVID-­19 illness and death (p for non-­linearity <0.001) with a flattening of the dose–response curve at around 500 MET-­min per week. Conclusions Regular physical activity seems to be related to a lower likelihood of adverse COVID-­19 outcomes. Our findings highlight the protective effects of engaging in sufficient physical activity as a public health strategy, with potential benefits to reduce the risk of severe COVID-­19. Given the heterogeneity and risk of publication bias, further studies with standardised methodology and outcome reporting are now needed. PROSPERO registration number CRD42022313629.