Daily Step Counts Could Influence Mortality Risk in US Adults

Kosuke Inoue, MD, PhD

Courtesy of LinkedIn

A new study investigating the association of daily step patterns with mortality in US adults revealed a curvilinear dose-response association between the number of days taking 8000 steps or more and a lower risk of all-cause and cardiovascular mortality over 10 years.¹

The findings suggest individuals who only took 8000 steps or more 1 or 2 days during the week showed a substantial reduction in mortality, but the protective association was shown to plateau when individuals took sufficient daily steps for 3 days or more.

“Our study findings suggest that for those individuals who face difficulties in exercising regularly (e.g., due to work and/or family obligations), achieving recommended daily steps only a couple days per week can have meaningful health benefits,” wrote the investigative team.

The team from Kyoto University, led by Kosuke Inoue, MD, PhD, indicated physical inactivity is a major public issue, contributing to an estimated 3.2 million deaths and $54 billion in direct health costs annually. Daily steps have been used as a simple measure of physical activity, but existing challenges, such as lack of time, often make it hard for adults to take the amount linked to substantial health benefits, such as 8000 steps or more.

As Inoue and colleagues indicated, prior studies reported the estimated health benefits for those who concentrate their physical activity to 1 or 2 days a week are similar to those with regular physical activity patterns. However, data were often self-reported which raised concerns on the accuracy of the data due to social desirability bias and there was lacking evidence on the number of days per week needed to prevent long-term adverse health outcomes.

To bridge this gap in knowledge, the investigative team used a nationally representative sample of US adults to investigate the dose-response association of the number of days taking 8000 steps or more (equal to walking approximately 4 miles) throughout a week based on an accelerometer. Data were collected from the 2005 and 2006 National Health and Nutrition Examination Surveys (NHANES) and linked to the National Death Index until 2019.

Among 4372 participants aged 20 years and older for whom data on daily step counts based on an accelerometer were available, 3120 had information on 4 or more valid days. Step counts were recorded over 60-second intervals each day. Investigators categorized participants into 3 groups according to the number of days per week they took 8000 steps or more: 0 days, 1 to 2 days, and 3 to 7 days.

Multivariable ordinary least squares regression models were used by the team to estimate adjusted risk differences (aRDs) for all-cause and cardiovascular mortality during the 10-year follow-up, adjusting for age, sex, race and ethnicity, insurance status, marital status, smoking, comorbidities, and average daily step counts. Data were analyzed from April 2022 – January 2023.

Among a sample population of 3101 participants (mean age, 50.5 years; 1583 women [51.0%]), 632 (20.4%) took 8000 steps or more 0 days per week, 532 (17.2%) took 8000 steps or more 1 to 2 days per week, and 1937 (62.5%) took 8000 or more steps 3 to 7 days per week. Over the 10 years of follow-up, 439 deaths (14.2%) from all-causes and 148 (5.3%) from cardiovascular disease were identified by investigators.

Compared with those who took 8000 steps or more 0 days per week, data showed the 10-year all-cause mortality risk was 14.9% lower among those who took 8000 steps or more 1 to 2 days per week and 16.5% lower among those who those who took 8000 steps or more 3 to 7 days per week. Moreover, the 10-year cardiovascular risk was 8.1% lower among those who took 8000 steps or more 1 to 2 days per week and 8.4% lower among those who took 8000 steps or more 3 to 7 days per week compared with 0 days per week.

The restricted cubic spline model showed a curvilinear association between the number of days per week taking 8000 steps or more and the risk of all-cause and cardiovascular mortality. The estimated association was also robust to using different thresholds between 6000 and 10,000 steps for the daily step counts, according to Inoue and colleagues.

Although Inoue and colleagues included an extensive set of covariates, they noted the findings still have residual confounding bias, as poor health could influence daily step counts and mortality risk. However, they suggest that “people may receive substantial health benefits even if a sufficient number of steps are taken on only a couple days of the week.”

References

1. Inoue K, Tsugawa Y, Mayeda ER, Ritz B. Association of Daily Step Patterns With Mortality in US Adults. JAMA Netw Open. 2023;6(3):e235174. doi:10.1001/jamanetworkopen.2023.5174