Step Accumulation Patterns and Risk for Cardiovascular Events and Mortality Among Suboptimally Active Adults

Background: Although physical activity recommendations increasingly consider daily step counts, it remains unclear whether step accumulation patterns—short versus sustained longer bouts—affect associations with mortality and cardiovascular disease (CVD) among suboptimally active populations. Objective: To examine associations of step accumulation patterns with all-cause mortality and CVD incidence in persons with 8000 or fewer daily steps. Design: Prospective cohort study. Setting: UK Biobank (2013 to 2015). Participants: 33 560 persons (mean age, 62.0 years [SD, 7.7]) who were engaging in 8000 or fewer daily steps and were free of CVD or cancer at baseline. Intervention: Participants were categorized as having activity bouts of shorter than 5 minutes, 5 to shorter than 10 minutes, 10 to shorter than 15 minutes, or 15 minutes or longer according to the bout in which they accumulated most of their steps. Sedentary participants had fewer than 5000 daily steps, and low-active participants had 5000 to 7999 daily steps. Measurements: All-cause mortality and CVD incidence. Inverse probability weighting was used to balance covariates across bout duration groups. Results: Over an average 7.9-year follow-up (266 283 person-years), 735 deaths and 3119 CVD events occurred. Cumulative all-cause mortality at 9.5 years decreased with bout length: For bouts shorter than 5 minutes, it was 4.36% (95% CI, 3.52% to 5.19%); for 5 to shorter than 10 minutes, 1.83% (CI, 1.29% to 2.36%); for 10 to shorter than 15 minutes, 0.84% (CI, 0.13% to 1.53%); and for 15 minutes or longer, 0.80% (CI, 0.00% to 1.89%). Cumulative CVD incidence at 9.5 years followed a similar pattern: For bouts shorter than 5 minutes, it was 13.03% (CI, 11.92% to 14.14%); for 5 to shorter than 10 minutes, 11.09% (CI, 9.88% to 12.29%); for 10 to shorter than 15 minutes, 7.71% (CI, 5.67% to 9.70%); and for 15 minutes or longer, 4.39% (CI, 1.89% to 6.83%). Limitation: Observational design with potential residual confounding and reverse causation; one-time measurement of activity. Conclusion: Suboptimally active adults who accumulated most of their daily steps in longer bouts had lower mortality and CVD risk than those who accumulated most daily steps in shorter bouts.