[Indoor sporting during the COVID-19 pandemic: analysis with data from the COVID RADAR app]

Indoor sporting locations have been forced to stay closed longer than outdoor sporting locations during the lockdowns introduced during the COVID-19 pandemic. This research addresses the question whether exercising indoors does raise one's risk of infection with SARS-CoV‑2. This analysis was performed using data from the COVID RADAR app and accounted for user differences in age, vaccine status, sex, other risky behavior, SARS-CoV‑2 prevalence and quality of living environment. Analyzing data from 1,353 users, 13.1% of which reported a positive SARS-CoV‑2 test, we found that exercising indoors leads to an odds ratio of 1.8 with a positive SARS-CoV‑2 test (95%-confidence interval 1.2-2.6, p = 0.003), as compared to users who exercise outdoors. This confirms the justification used in longer closing indoor sporting locations to reduce the number of infections.