Aims: This study aimed to examine the theoretical effects of replacing television (TV) viewing with different intensities of physical activity on COVID-19 mortality risk using isotemporal substitution models.
Methods: The analytical sample was composed of 359,756 UK Biobank participants. TV viewing and physical activity were assessed by self-report. Logistic regressions adjusted for covariates were used to model the effects of substituting an hour a day of TV viewing with an hour of walking, moderate-intensity physical activity (MPA) or vigorous-intensity physical activity (VPA) on COVID-19 mortality risk.
Results: From 16 March 2020 to 12 November 2021, there were 879 COVID-19 deaths in the analytical sample. Substituting an hour a day of TV viewing with an hour of walking was associated with a 17% lower risk of COVID-19 mortality (odds ratio (OR)=0.83, 95% confidence interval (CI) 0.74-0.92). In sex-stratified analyses, the same substitution was associated with a lower risk in both men (OR=0.85, 95% CI 0.74-0.96) and women (OR=0.78, 95% CI 0.65-0.95). However, replacing an hour a day of TV viewing with an hour of MPA was only associated with a lower risk in women (OR=0.80, 95% CI 0.65-0.98).
Conclusions: Replacing TV viewing with walking was associated with a significant reduction in COVID-19 mortality risk. Public health authorities should consider promoting the replacement of TV viewing with walking as a protective strategy against COVID-19 mortality.
Keywords: Sedentary behaviour; coronavirus; epidemiology; inactivity; screen-time.