Step and exercise time goals are equally helpful

In the era of smartwatches, tracking your step count has become easier than ever, but current physical activity recommendations do not provide specific steps for staying healthy. A new study led by researchers at Brigham and Women's Hospital, a founding member of Mass General Brigham, suggests that both step and time goals in exercise are equally associated with reduced risk of premature death and cardiovascular disease. Thus, choosing a goal—steps or time—may be less important than choosing a goal that matches personal preferences.

The results are published in an article entitled “Time- and Step-Based Physical Activity Metrics for Health” in JAMA Internal Medicine.

Physical activity reduces the risk of chronic diseases and infections, and also promotes longevity. Current US guidelines, last updated in 2018, recommend that adults engage in at least 150 minutes of moderate to vigorous physical activity (such as brisk walking) or 75 minutes of vigorous activity (such as jogging) per week.

At that time, most of the available evidence for health benefits was based on studies in which participants self-reported their physical activity. There was little evidence of the relationship between step count and health.

Fast forward to now, wearables have become ubiquitous and step count is now a popular metric among many fitness tracking platforms. How do time goals compare to step goals? Researchers sought to answer this question.

“We recognized that existing physical activity guidelines primarily focus on duration and intensity of activity but do not provide step recommendations,” said lead author Rikuta Hamaya, MD, PhD, MS, a researcher in the Department of Preventive Medicine at BWH.

“With more people using smartwatches to measure their steps and overall health, we saw the importance of determining how step measurements compare to time goals as they relate to health outcomes—which is better?”

In this study, researchers collected data from 14,399 women participating in the Women's Health Study who were healthy (free from heart disease and cancer).

Between 2011 and 2015, participants aged 62 years and older were required to wear research wearable devices for seven consecutive days to record their physical activity levels, removing the devices only for sleep or water activities.

Surveys were conducted annually during the study period to determine the health outcomes of interest, specifically death from all causes and cardiovascular disease. Scientists monitored the participants until the end of 2022.

While wearing the devices, the researchers found that participants engaged in an average of 62 minutes of moderate to vigorous physical activity per week and accumulated an average of 5,183 steps per day. During an average follow-up period of nine years, about 9% of participants died and about 4% developed cardiovascular disease.

Higher levels of physical activity (measured by both the number of steps and time spent in moderate to vigorous activity) were associated with a significant reduction in the risk of death or cardiovascular disease—the most active quarter of women had a 30–40% reduced risk compared to the least active quarter. And, according to time and step measurements, people in the top three quarters of physical activity levels lived an average of 2.22 and 2.36 months longer, respectively, compared with the bottom quarter, over a nine-year follow-up. This survival advantage persisted regardless of differences in body mass index (BMI).

While both metrics are useful for assessing health, Hamaya explained that each has its own advantages and disadvantages. For example, the number of steps may not account for differences in fitness levels. For example, if a 20-year-old and an 80-year-old walk for 30 minutes at a moderate intensity, their step counts may differ significantly.

On the other hand, steps are easy to measure and less subject to interpretation compared to exercise intensity. Additionally, steps capture even sporadic movements of daily living, not just exercise, and these types of activities are likely performed by older adults.

“For some, especially younger people, physical activity may include activities such as tennis, soccer, walking or jogging that are easily tracked in steps. However, for others it may be cycling or swimming, where it is easier to control the duration of the exercise. Therefore, it is important that physical activity guidelines offer multiple ways to achieve goals. Movement looks different for everyone, and almost all forms of movement are good for our health,” Hamaya said.

The authors note that this study included only a one-time assessment of time- and step-based physical activity metrics. Additionally, the majority of women in the study were white and of high socioeconomic status.

Finally, this study was observational and therefore cause and effect cannot be proven. In the future, Hamaya plans to collect more data through a randomized controlled trial to better understand the relationship between time- and step-based exercise metrics and health.

Senior author Yi-Ming Lee, MBBS, ScD, an epidemiologist in the Department of Preventive Medicine at BWH, concluded: “The next federal physical activity guidelines are planned for 2028. Our results further highlight the importance of adding step-based goals to allow for the flexibility of goals that suit people with different preferences, abilities, and lifestyles."