We investigated the association of changes in the frequency of moderate-to-vigorous physical activity (MVPA) and the risks of all-cause and cardiovascular disease (CVD) mortality. This study used the nationally representative National Health Insurance Service-National Sample Cohort database. We included 286,402 individuals aged ≥20 years and estimated changes in the frequency of MVPA over a two-year period. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard regression models. The HRs (95% CIs) for the risk of all-cause and CVD mortality for an increased frequency of MVPA from physical inactivity compared with continual physical inactivity were 0.82 and 0.68 (0.73-0.92 and 0.51-0.91) for 1-2, 0.72 and 0.48 (0.62-0.84 and 0.31-0.74) for 3-4, and 0.73 and 0.70 (0.63-0.85 and 0.50-0.98) for ≥5 sessions of MVPA/week. The HRs (95% CIs) for the risk of all-cause and CVD mortality were 1.28 and 1.58 (1.07-1.53 and 1.01-2.46), 1.25 and 2.17 (1.01-1.57 and 1.14-4.12), and 1.43 and 1.44 (1.15-1.77 and 0.84-2.47) for changes from 1-2, 3-4, and ≥5 sessions of MVPA/week to physical inactivity, respectively. This study showed the beneficial effect of increasing physical activity, particularly for those who were physically inactive at baseline, as well as the increased risk of all-cause and CVD mortality after adapting a physically inactive lifestyle regardless of their baseline physical activity status.
Keywords: cardiovascular diseases; exercise; heart disease risk factors; moderate-to-vigorous physical activity; mortality; sedentary behavior.