Timing of moderate-to-vigorous physical activity, mortality, cardiovascular disease, and microvascular disease in adults with obesity

Objective To assess the association between timing of aerobic moderate-to-vigorous physical activity (MVPA) and risk of cardiovascular disease (CVD), microvascular disease (MVD), and all-cause mortality in adults with obesity, and a subset with obesity and type 2 diabetes (T2D). Research Design and Methods Participants included adults with obesity (body mass index [BMI] >30kg/m2), and a subset with T2D, from the UK Biobank accelerometry sub-study. Aerobic MVPA was defined as bouts lasting ≥3 continuous minutes. Participants were categorised into Morning, Afternoon, or Evening MVPA based on when they undertook the majority of their aerobic MVPA. The reference group included participants with an average of <1aerobic MVPA bout/day. Analyses were adjusted for potential confounders. Results The core sample included 29,836 adults with obesity and a mean age of 62.2 (standard deviation [SD] 7.7) years. Over a mean follow-up of 7.9 (SD 0.8) years, 1,425 deaths, 3,980 CVD events, and 2,162 MVD events occurred. Compared to the reference group, Evening MVPA was associated with the lowest risk of mortality (hazard ratio [HR]=0.39 [95% confidence interval [CI]:0.27,0.55]), whereas Afternoon (HR=0.60[95%CI:0.51,0.71]) and Morning MVPA (HR=0.67[95%CI:0.56,0.79]) demonstrated significant but weaker associations. Analogous patterns were observed for CVD and MVD incidence, with Evening MVPA being associated with the lowest risk for CVD (HR=0.64[95%CI:0.54,0.75]), and MVD (HR=0.76[95%CI:0.63,0.92]). Findings were similar in the T2D subset (n=2,995). Conclusions Aerobic MVPA bouts undertaken in the evening were associated with the lowest risk of mortality, CVD, and MVD. Timing of physical activity may play a role in future obesity and T2D management.