Associations of timing of physical activity with all-cause and cause-specific mortality in a prospective cohort study

Abstract

There is a growing interest in the role of timing of daily behaviors in improving health. However, little is known about the optimal timing of physical activity to maximize health benefits. We perform a cohort study of 92,139 UK Biobank participants with valid accelerometer data and all-cause and cause-specific mortality outcomes, comprising over 7 years of median follow-up (638,825 person-years). Moderate-to-vigorous intensity physical activity (MVPA) at any time of day is associated with lower risks for all-cause, cardiovascular disease, and cancer mortality. In addition, compared with morning group (>50% of daily MVPA during 05:00-11:00), midday-afternoon (11:00-17:00) and mixed MVPA timing groups, but not evening group (17:00-24:00), have lower risks of all-cause and cardiovascular disease mortality. These protective associations are more pronounced among the elderly, males, less physically active participants, or those with preexisting cardiovascular diseases. Here, we show that MVPA timing may have the potential to improve public health.

Fig. 1. The associations of total MVPA volume, MVPA within time windows, and fractions of MVPA within time windows with mortality risk.

a–c The associations between total MVPA volume and mortality outcomes. The hazard ratios (HRs) were adjusted for age, sex, ethnicity, Townsend deprivation index, recruitment center, education level, the season of accelerometer wear, smoking status, alcohol intake, healthy diet score, sleep duration (<7, 7–8 h, >8 h), and sleep midpoint. d–f The associations between MVPA within three time windows and mortality outcomes. The HRs were adjusted for age, sex, ethnicity, Townsend deprivation index, recruitment center, education level, the season of accelerometer wear, smoking status, alcohol intake, healthy diet score, sleep duration (<7, 7–8, >8 h), sleep midpoint, and MVPA volume during other two time windows. g–i The associations between the fractions of MVPA within three time windows with mortality risk (indicating MVPA timing effects). The HRs were adjusted for age, sex, ethnicity, Townsend deprivation index, recruitment center, education level, the season of accelerometer wear, healthy diet score, smoking status, alcohol intake, sleep duration (<7, 7–8, >8 h), sleep midpoint, and total MVPA volume. CVD cardiovascular disease, MVPA moderate to vigorous physical activity. Error bands represent the 95% confidence intervals for each effect estimate. Source data are provided as a Source Data file.

Fig. 2. Subgroup analysis on the associations between favorable timing of MVPA (midday-afternoon & mixed vs. morning & evening) and mortality risk stratified by age and sex categories.

^aP values remained significant after multiple testing with the FDR method. Cox proportional hazard regression was used to examine the associations, which were adjusted for age, sex, ethnicity, Townsend deprivation index, recruitment center, education level, the season of accelerometer wear, smoking status, alcohol intake, healthy diet score, sleep duration (<7, 7–8, >8 h), sleep midpoint, and total MVPA volume (Model 3). According to their associations with mortality (Table 2), four timing groups were combined into two groups: (1) favorable timing of MVPA (i.e., midday-afternoon or mixed); (2) unfavorable (i.e., morning or evening). This combination method facilitated the analysis and interpretation of multiplicative and additive interaction effects, which was widely used in previous studies [Shan et al. BMJ, 2018.; Huang et al. Br J Sports Med. 2021]. CVD cardiovascular disease, CI confidence interval, MVPA moderate to vigorous physical activity. Error bars represent the 95% CIs for each effect estimate. Source data are provided as a Source Data file.