Should Movement Goals Be In Minutes Or Steps?

Guidelines for physical activity in the United States recommend that most adults engage in at least 150 minutes of moderate to vigorous physical activity, or 75 minutes of vigorous physical activity every week based on a mountain of scientific evidence demonstrating that physical activity helps to reduce the risk of developing chronic illness and infection as well as promoting longevity. This study builds on that research making use of wearables to compare how time-based goals measure against step-based goals. 

“We recognized that existing physical activity guidelines focus primarily on activity duration and intensity but lack step-based recommendations,” said lead author Rikuta Hamaya, MD, PhD, MS, a researcher in the Division of Preventive Medicine at BWH. “With more people using smartwatches to measure their steps and overall health, we saw the importance of ascertaining how step-based measurements compare to time-based targets in their association with health outcomes – is one better than the other?”

To answer this question, data was collected from 14,399  cardiovascular-disease and cancer-free women aged 62+ years old who were enrolled in the Women’s Health Study who wore research-grade wearables for seven consecutive days between 2011 and 2015 to record their physical activity that were only removed for sleep and water-related activities. Participants also filled out questionnaires to ascertain health outcomes of interest, in particular, death from any cause and cardiovascular disease, and they were followed until the end of 2022.

The analysis revealed that the participants engaged in a median of 62 minutes of moderate to vigorous intensity physical activity per week, and they accumulated a median of 5,183 steps per day. During the 9-year median follow up the analysis also revealed that 9% of the participants had died and 4% developed cardiovascular disease. 

The researchers found that higher levels of physical activity assessed as step counts of time activity were associated with significant reductions in the risk of death and cardiovascular disease, with those in the most active quartile experiencing 30-40% reductions compared to those in the least active. Those in the top three quartiles outlived those in the bottom quartile by an average of 2.22 and 2.36 months respectively based on both time and step measurements at the 9 year follow, and this persisted regardless of differences in BMI.

Hamaya explained that both measurements are useful, each has its advantages and disadvantages. For example, step counts do not account for different levels of fitness, but they are also less subject to interpretation compared to exercise intensity, and step count also captures nearly all movement throughout the day, not just exercise. 

“For some, especially for younger individuals, exercise may involve activities like tennis, soccer, walking or jogging, all of which can be easily tracked with steps. However, for others, it may consist of bike rides or swimming, where monitoring the duration of exercise is simpler. That’s why it’s important for physical activity guidelines to offer multiple ways to reach goals. Movement looks different for everyone, and nearly all forms of movement are beneficial to our health,” said Hamaya.

“Our current physical activity guidelines for Americans, published in 2018, indicate the recommended frequency and duration of physical activity for adults. However, it was not able to recommend a certain number of steps each day for overall health benefits,” said Evenson. “With new research, such as this study and others, we are hopeful that the next iteration of the guidelines might be able to make a step recommendation for health.”

 “The next federal physical activity guidelines are planned for 2028. Our findings further establish the importance of adding step-based targets, in order to accommodate flexibility of goals that work for individuals with differing preferences, abilities and lifestyles,” concluded Senior author I-Min Lee, MBBS, ScD, an epidemiologist in the Division of Preventive Medicine at BWH.