Timing of Moderate-to-Vigorous Physical Activity and Mortality Risk: Role of Chronotype and Sleep Patterns

Area of Science:

• Epidemiology
• Chronobiology
• Public Health

Background:

• Diurnal patterns of physical activity are increasingly recognized as important for health.
• Understanding how the timing of moderate-to-vigorous physical activity (MVPA) influences mortality risk is crucial for public health guidelines.
• Individual chronotype and sleep patterns may modulate the relationship between physical activity timing and health outcomes.

Purpose of the Study:

• To investigate if diurnal patterns of MVPA are associated with all-cause, cancer, and cardiovascular disease (CVD) mortality, independent of total activity volume.
• To explore whether these associations differ based on an individual's chronotype and sleep midpoint.
• To compare mortality risks across different MVPA timing patterns (early-morning, consistently active, midday, evening) and an inactive group.

Main Methods:

• Prospective cohort study of 75,509 UK Biobank participants (aged 40-73 years) with accelerometry data.
• Activity timing patterns were identified using K-means clustering of hourly MVPA distribution among guideline-adherent individuals.
• Cox proportional hazards models and Fine-Gray competing-risk models were used to assess mortality risk, adjusting for total MVPA volume and other covariates.

Main Results:

• Among adults meeting MVPA guidelines, a midday-active pattern was associated with a significantly lower risk of all-cause mortality (HR 0.79, 95% CI 0.65-0.97) compared to a consistently active pattern, independent of MVPA volume.
• Associations with cancer and CVD mortality were attenuated and not statistically significant.
• All active timing patterns were associated with substantially lower mortality risk compared to the inactive group, with midday activity showing the largest reduction.

Conclusions:

• A midday pattern of moderate-to-vigorous physical activity is associated with reduced all-cause mortality risk among adults who meet physical activity guidelines, independent of the total volume of activity.
• While meeting MVPA guidelines confers broad mortality benefits regardless of timing, specific timing patterns may offer additional advantages.
• These findings suggest that incorporating physical activity timing into public health guidance could optimize health benefits.