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Recent findings showed that step-based and minute-based exercise were equally effective for reducing mortality risk in older women.

Whether tracked by time or steps, physical activity is equally effective at preventing cardiovascular disease (CVD) and death in older women, so whichever method they prefer is fine, as the results of a recent observational study suggest.

Among older women, “MVPA [moderate to vigorous physical activity] time and step counts were qualitatively similar in their associations with all-cause mortality and CVD,” Rikuta Hamaya, MD, PhD, MS, and colleagues wrote in JAMA Internal Medicine.

“Step count-based goals should be considered for future guidelines along with time-based goals, allowing for the accommodation of personal preferences,” they added. “In the meantime, clinicians can reasonably prescribe step-based goals, if they prefer, to older patients.”

US Guidelines Consider Time Spent & Not Steps Taken

Current US Physical Activity Guidelines for Americans recommend at least 150 minutes per week of MVPA, but no evidence-based analogous step-based guidance is available.

To fill that knowledge gap, the research team compared how MVPA time tracking versus step counts are linked with all-cause mortality and CVD. Their cohort study analyzed ongoing follow-up data from surviving participants 62 years of age or older who enrolled in the 1992 to 2004 Women’s Health Study and were free from CVD and cancer. They used Cox proportional hazards regression models, restricted mean survival time differences, and area under the receiver operating characteristic curve (AUC) to analyze the associations.

The 14,399 women in the current ancillary study averaged 71.8 years of age. Between 2011 and 2015, each participant wore an accelerometer on their hip once for 7 consecutive days except for sleep and water-related activities. The device recorded both the length of MVPA time and the number of steps taken. The women also completed annual questionnaires on sociodemographic details, health habits, and personal and family medical history.

After following the women through 2022, the researchers found that:

• The median MVPA time was 62 minutes per week, and the median number of steps was 5,183 a day.
• Over the median follow-up of 9 years, the hazard ratios (HR) per standard deviation for all-cause mortality were 0.82 (95% CI, 0.75-0.90) for MVPA time and 0.74 (95% CI, 0.69-0.80) for step counts.
• At 9 years, participants in the top three quartiles of MVPA time and step counts survived longer than those in the bottom quartile: 2.22 (95% CI, 1.58-2.85) months longer for time and 2.36 (95% CI, 1.73-2.99) months longer for step.
• Over the median follow-up of 9.0 years, 1,330 (9.2%) people died and 588 (4.1%) developed CVD.
• The AUCs for all-cause mortality related to both MVPA time and step metrics were identical: 0.55 (95% CI, 0.52-0.57), and the AUCs for CVD were 54 (95% CI, 0.51-0.57) and 0.52 (95% CI, 0.50-0.55).

The authors noted that the strengths of their study include its use of a research-quality accelerometer, large sample size, long follow-up, and rigorous statistical methods. Limitations include missing potential changes over time due to testing each person only once and being unable to generalize the findings due to many participants being “of higher socioeconomic status,” more active, and White.  

Step Counting May Be More Convenient

In an accompanying editorial, Cary P. Gross, MD, and Raegan W. Durant, MD, MPH, wrote, “Asking people to keep track of their time spent exercising each week may be adding another hurdle to enhancing activity levels. Rather than assessing the amount of time exercising, daily step counts may be a more attractive way of measuring physical activity. Many people have mobile devices with built-in accelerometers, with their daily steps counted as a matter of routine.”

Dr. Gross and Dr. Durant joined the researchers in recommending further related studies that include more diverse populations and that measure other health outcomes.

“Time spent in dedicated physical exertion compared with step counts reflects related yet differing aspects of physical activity, and both are highly relevant to improving clinical outcomes, including mortality,” the editorialists advised. “Capturing both metrics in future research will help to advance research on physical activity and health.”