Setting your clock: associations between timing of objective physical activity and cardiovascular disease risk in the general population.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 36372091 · doi:10.1093/eurjpc/zwac239
What was done
Analyzed 86,657 UK Biobank participants (58% female, mean age 61.6 ± 7.8 years, mean BMI 26.6 ± 4.5 kg/m²) who wore a triaxial accelerometer for a 7-day period. K-means clustering categorized participants into distinct daily physical activity timing profiles (chronoactivity) irrespective of mean daily activity intensity. Multivariable-adjusted Cox proportional hazard models estimated hazard ratios for incident cardiovascular disease (CVD) events across clusters over a 6-year follow-up, adjusting for age, sex, and baseline cardiovascular risk factors, with stratified analyses by sex, overall activity level, and self-reported chronotype.
What was found
During the 6-year follow-up, 3,707 incident CVD events occurred. Compared to a midday activity pattern, participants with a late morning physical activity pattern had a lower risk of incident coronary artery disease (HR 0.84, 95% CI 0.77 to 0.92) and incident stroke (HR 0.83, 95% CI 0.70 to 0.98). Associations were more pronounced in women (interaction P = 0.001). No evidence of effect modification was found by total physical activity level or self-reported sleep chronotype.
Why it matters
These findings suggest that timing physical activity in the morning may provide cardiovascular benefits beyond the total volume of daily exercise.
Limits
Physical activity was objectively measured for only one 7-day window, which may not reflect long-term habitual timing patterns. The observational design cannot rule out residual confounding or determine causal mechanisms. UK Biobank participants are predominantly of European descent and subject to healthy-volunteer selection bias.
Cited by
- supports An accelerometry study found that individuals whose primary physical activity occurs between 8:00 AM and 11:00 AM have up to a 27% lower stroke risk than those doing equivalent exercise volume later in the day.