Steps per Day and All-Cause Mortality in Middle-aged Adults in the Coronary Artery Risk Development in Young Adults Study.
Level 3 - non-randomized controlled study
Prospective cohort study
PubMed 34477847 · doi:10.1001/jamanetworkopen.2021.24516
What was done
This prospective cohort study evaluated 2,110 participants (aged 38–50 years; 57.1% women, 42.1% Black) from the Coronary Artery Risk Development in Young Adults (CARDIA) study who wore an accelerometer during 2005–2006. Daily step volume was categorized into low (<7,000 steps/d), moderate (7,000–9,999 steps/d), and high (≥10,000 steps/d). Stepping intensity was evaluated as peak 30-minute stepping rate and time spent at ≥100 steps/min. Participants were followed for a mean of 10.8 years for premature all-cause mortality using multivariable-adjusted Cox proportional hazards models.
What was found
Over 22,845 person-years of follow-up, 72 participants (3.4%) died. Compared with the low step group, mortality risk was significantly lower in the moderate group (HR 0.28 [95% CI, 0.15–0.54]; risk difference 53 [95% CI, 27–78] events per 1,000 people) and high step group (HR 0.45 [95% CI, 0.25–0.81]; risk difference 41 [95% CI, 15–68] events per 1,000 people). Reduced mortality was seen in Black participants (HR 0.30 [95% CI, 0.14–0.63]), White participants (HR 0.37 [95% CI, 0.17–0.81]), women (HR 0.28 [95% CI, 0.12–0.63]), and men (HR 0.42 [95% CI, 0.20–0.88]). Neither peak 30-minute intensity (HR 0.98 [95% CI, 0.54–1.77]) nor time at ≥100 steps/min (HR 1.38 [95% CI, 0.73–2.61]) was significantly associated with mortality.
Why it matters
Accumulating at least 7,000 steps per day is associated with substantially reduced premature mortality in middle-aged adults, with daily volume mattering more than stepping intensity.
Limits
The observational design cannot establish causality or exclude residual confounding and reverse causation. Accelerometry was assessed during a single baseline period (2005–2006) rather than updated over time. The overall number of mortality events was relatively small (72 deaths), limiting statistical power in some subgroup comparisons.
Cited by
- supports Daily physical activity exceeding a threshold of 7,000 steps per day provides significant health benefits.