The goal of completing 10,000 steps per day is widely promoted although, evidence to support its benefits is sparse and the evidence of implications on mortality rates is limited. To date, higher step counts have been linked to decreased mortality but most prior research has focused on older demographics, those with debilitating chronic conditions, or groups with relatively few deaths making the findings challenging to generalize. Higher gait speeds and self-reported walking paces may be associated with lower mortality risk although, conflicting evidence exists regarding accelerometer-measured step intensity and improved cardiometabolic health.
To clarify the relationship between step count, intensity, and adult mortality, a team of researchers set out to define the dose-response relationships between these factors in a representative sample of U.S. adults aged 40 or older. The recent study published in JAMA reported a decreased mortality rate associated with a greater daily step count but no significant correlation between step intensity.
Investigating Daily Step Patterns
As part of their study, the research team examined data from the National Health and Nutrition Examination Survey of a representative sample of U.S. adults aged at least 40 years who wore an accelerometer for up to 7 days. A total of 4840 participants with a mean age of 56.8 years were included in the study, 54% were women and 36% participants had obesity. The accelerometers were worn for a mean of 5.7 days and a mean of 14.4 hours per day.
The examined exposures were the accelerometer-measured number of steps per day and 3 different step intensity measures, including extended bout cadence, peak 30-minute cadence, and peak 1-minute cadence. The primary outcome was all-cause mortality while secondary outcomes were cardiovascular disease (CVD) and cancer mortality. Hazard ratios, mortality rates, and confidence intervals were estimated and adjusted for relevant factors.
Effects of Step Count and Intensity
Researchers observed a mean number of steps per day of 9,124 in the participant cohort. Overall, there were 1,165 deaths recorded over the mean follow-up period of 10.1 years, which included 406 cardiovascular disease and 283 cancer deaths.
The unadjusted incidence density for all-cause mortality was 76.7 per 1,000 person-years (or 419 deaths) for the 655 individuals who took less than 4,000 steps per day. For the 1,727 participants who took between 4,000 and 7,999 steps per day, the density was 21.4 per 1,000 person-years, or 488 deaths. For the 1,539 individuals who took between 8,000 and 11,999 steps per day, the unadjusted incidence density was 6.9 per 1,000 person-years, or 176 deaths. Finally, in the 919 individuals who took the most steps daily at a minimum of 12,000 steps per day, the density was 4.8 per 1,000 person-years (82 deaths).
When compared with participants who took 4,000 steps per day, those taking 8,000 steps per day had a significantly lower all-cause mortality, as did those taking 12,000 steps per day. The research team then defined the unadjusted incidence density for all-cause mortality by peak 30-minute cadence; the density was 32.9 per 1,000 person-years (406 deaths) for the 1,080 participants who took between 18.5 to 56.0 steps per minute. For the 1,153 individuals who took between 56.1 to 69.2 steps per minute, the density was 12.6 per 1,000 person-years, or 207 deaths. In the group of 1,074 participants who took between 69.3 and 82.8 steps per minute, the result was 6.8 per 1,000 person-years, or 124 deaths. Finally, for the 1,037 participants who took between 82.9 and 149.5 steps per minute, the rate was 5.3 per 1,000 person-years, resulting in 108 deaths.
After adjusting for total steps taken per day, the authors’ findings revealed that greater step intensity was not significantly associated with lower mortality, however, a greater number of steps per day was significantly associated with lower all-cause mortality. The latest findings provide tangible evidence in support of the well-established recommendation to take a greater number of steps per day for cardiometabolic health benefits. Based on these results, patients should be encouraged to take a minimum of 8,000 steps daily to meaningfully impact their all-cause mortality risk.