Higher daily step counts associated with reduced risk for chronic diseases

Increasing daily step counts may reduce the risk for chronic diseases such as obesity, sleep apnea and major depressive disorder, a study published in Nature Medicine found.

While noting previous studies have found associations between fewer step counts and higher risks for CVD and mortality, Hiral Master, PT, PhD, MPH, CPH, a senior scientist at Vanderbilt University Medical Center, and colleagues wrote that they failed to answer important questions due to several design limitations.

In addition to activity being potentially over- or underreported due to self-questionnaires, the researchers noted that studies focused on a “relatively targeted set of outcomes” limited to diabetes, mortality and CVD.

“Little is known about the impact of activity over time on developing chronic diseases across the full human phenome, which represents the sum of human traits and conditions resulting from genetic and behavioral variation in a population,” they wrote.

Aiming to examine those underreported associations, Master and colleagues examined data from the NIH’s All of Us Research Program, an initiative that collects multiple streams of information including genomics, electronic health records and wearable fitness trackers.

The analysis included 6,042 adults who — in addition to sharing EHR data — linked their own Fitbit device and had more than 6 months of Fitbit monitoring data. Participants had a median age of 56.7 years.

The data were adjusted for age, sex and race and set to an effect size of 1,000 steps per odds ratio (OR). An OR less than 1 indicated that higher step counts were associated with lower disease risks.

Master and colleagues found that participants averaged a median step count of 7,731 per day over a monitoring duration of 4 years. Incident chronic diseases that had the highest effect sizes over a minimum 6 months of monitoring were:

• obstructive sleep apnea (OR = 0.88; 95% CI, 0.84-0.92);
• obesity (OR = 0.89; 95% CI; 0.86-0.93);
• type 2 diabetes with neurological manifestations (OR = 0.69; 95% CI, 0.6-0.79);
• hypertension (OR = 0.92; 95% CI, 0.89-0.95).
• gastroesophageal reflux disease, or GERD (OR = 0.92; 95% CI, 0.89-0.95); and
• major depressive disorder, or MDD (OR = 0.92; 95% CI, 0.89-0.95).

Overall, the researchers found that taking more than 8,200 steps per day was associated with a reduced risk for obesity, sleep apnea, GERD and MDD, according to a press release accompanying the study.

The effect estimates varied by condition, with an HR for GERD, MDD, sleep apnea, obesity and diabetes ranging from 0.64 to 0.81.

Master and colleagues reported that the associations between step count intensity and disease incidence were inverse and linear for obesity, sleep apnea GERD and MDD, with lower risks at higher counts.

“For example, in comparison with the median step count, the risk of obesity declined by 31% [HR = 0.69; 95% CI 0.53-0.88],” the researchers wrote.

Meanwhile, hypertension and incident diabetes had nonlinear associations with step count, with no further risk reduction above 8,000 to 9,000 daily steps.

The researchers acknowledged limitations to the study, which included data not accounting for non-stepping physical activity — like swimming or cycling — as well as non-adjustment for differing Fitbit models and their variations of daily step counting, and the majority of participants being young, female (73%), white (84%) and college-educated (71%).

Master and colleagues wrote that the study could have clinical implications, pointing out that clinicians could monitor activity trends and provide evidence-based anticipatory guidance based on a patients’ health characteristics and risks.

“Self-reported physical activity or exercise interventions may have potential beneficial effects to lower the incidence of depression and lower the severity of obstructive sleep apnea and associated comorbidities,” they wrote.

The researchers concluded that their findings “provide a new, robust source of evidence in support of the physical activity guidelines to prevent the risk of developing chronic diseases,” and that a step count target of 8,000 to 9,000 per day could help lessen the risks for many conditions.

References:

• Counting steps can reduce disease risk: study. https://news.vumc.org/2022/10/10/counting-steps-can-reduce-disease-risk-study/. Published Oct. 10, 2022. Accessed Oct. 16, 2022.
• Master H, et al. Nat Med. 2022;doi:10.1038/s41591-022-02012-w.