Associations of accelerometer-measured light-intensity physical activity with mortality and incidence of cardiovascular diseases and cancers: A prospective cohort study.
Level 3 - non-randomized controlled study
Prospective observational cohort study
PubMed 41201595 · doi:10.1016/j.jshs.2025.101099
What was done
The authors analyzed 69,492 adults aged 43–78 years from the prospective UK Biobank cohort. Light-intensity physical activity (LPA) was measured via accelerometry and classified using a machine-learning Random Forest model into quartile groups (<3.9, 3.9 to <5.0, 5.0 to <6.1, and ≥6.1 h/day). All-cause mortality, cause-specific mortality (cardiovascular disease and cancer), and incident cardiovascular disease and cancer were tracked over a median follow-up of 8.04 years via primary care, hospital, and death registry records.
What was found
During follow-up, 2,024 all-cause deaths, 539 cardiovascular disease deaths, and 1,175 cancer deaths occurred. Compared with the lowest LPA quartile (<3.9 h/day), the hazard ratios (HR) for all-cause mortality were 0.82 (95% CI: 0.73–0.93) for 3.9 to <5.0 h/day, 0.75 (95% CI: 0.66–0.85) for 5.0 to <6.1 h/day, and 0.77 (95% CI: 0.68–0.88) for ≥6.1 h/day. A non-linear dose-response relationship showed a minimal effective dose of 3.59 h/day (HR = 0.81, 95% CI: 0.78–0.86) and an optimal dose of 5.72 h/day (HR = 0.63, 95% CI: 0.56–0.71) relative to the 5th percentile. Similar patterns were reported for cause-specific mortality and disease incidence.
Why it matters
This study defines specific minimal and optimal daily targets for light-intensity physical activity associated with lower mortality and chronic disease incidence. These volume thresholds can help inform future physical activity guidelines, particularly for individuals who cannot participate in moderate-to-vigorous exercise.
Limits
The observational design cannot establish causality and remains vulnerable to residual confounding or reverse causation. Baseline accelerometer assessment does not account for changes in physical activity over the 8-year follow-up. The UK Biobank cohort is not fully representative of the general population due to healthy-volunteer selection bias, and specific numerical risk estimates for incident disease outcomes were omitted from the abstract.
Cited by
- contradicts Light physical activity provides about a 10% to 15% risk reduction, but shows no further dose-response benefit with up to 2 to 3 hours per day.