In the modern era of smartwatches, keeping track of step counts has become increasingly accessible; however, the prevailing guidelines for physical activity do not specifically endorse particular step counts for health benefits. Recent research conducted by Brigham and Women’s Hospital, a foundational entity within Mass General Brigham, has indicated that both step counts and time-based exercise targets are comparably linked with a reduced risk of premature death and cardiovascular disease. Consequently, the choice between adopting a time-based or step-based goal might hinge more on individual preference than on distinct health advantages. These findings have been documented in JAMA Internal Medicine.
Physical activity is a proven deterrent against chronic diseases and infections and is a significant contributor to increased longevity. The current guidelines in the U.S., updated last in 2018, suggest that adults should engage in at least 150 minutes of moderate to vigorous physical activity per week, such as brisk walking, or 75 minutes of vigorous activity like jogging. Historically, much of the evidence for these recommendations was derived from studies relying on participants’ self-reported activity levels. At the time, limited data existed concerning the health impacts of specific step counts. Now, in an era where wearable technology is commonplace, step tracking has emerged as a popular feature on numerous fitness platforms. This shift prompted researchers to examine how goals based on time compare with those based on steps.
The study’s lead author, Rikuta Hamaya, MD, PhD, MS from the Division of Preventive Medicine at Brigham and Women’s Hospital, noted that while existing physical activity guidelines emphasise duration and intensity, they do not offer guidance on step counts. With a growing number of people utilising smartwatches for health monitoring, understanding how step-based measurements stack up against time-based goals in terms of health outcomes became a pivotal area of study.
Data for this research were gathered from 14,399 women participating in the Women’s Health Study, all of whom were free from cardiovascular disease and cancer at the outset. Between 2011 and 2015, these participants, who were aged 62 years and older, were instructed to wear research-grade wearable devices for seven consecutive days, removing them only for sleeping or water-based activities. Throughout the study, annual questionnaires were used to track health outcomes, particularly deaths from any cause and cardiovascular conditions, with follow-up continuing until the end of 2022.
Findings revealed that at the time they wore the devices, the women engaged in a median of 62 minutes of moderate-to-vigorous physical activity weekly and averaged 5,183 steps per day. Over a median follow-up period of nine years, about 9% of the participants died, and roughly 4% developed cardiovascular disease. Notably, higher activity levels, whether measured in steps or time spent in moderate-to-vigorous activity, were linked with significant reductions in the risks of death and cardiovascular disease. The most active women experienced risk reductions of 30-40% compared to those who were least active. Moreover, those in the top three activity quartiles lived an average of 2.22 to 2.36 months longer than those in the lowest quartile over the nine years, with this survival benefit persisting across different BMI categories.
Hamaya explained that both step and time measurements are valuable for assessing health status, but each has its advantages and limitations. For instance, while step counts are a straightforward metric, they might not entirely reflect differences in fitness levels; a 20-year-old and an 80-year-old might accrue different step counts from a 30-minute moderate-intensity walk. However, step tracking does capture incidental movements that are part of daily life, which are especially relevant for older adults.
“For some individuals, particularly the younger cohort, activities like tennis, soccer, walking, or jogging can be readily tracked with steps. For others, activities such as cycling or swimming might be easier to monitor by duration. Therefore, it’s essential for physical activity guidelines to offer varied avenues to achieve health goals. Movement differs for everyone, and almost all types of physical activity are beneficial,” Hamaya added.
The study authors acknowledge that this research is based on a single assessment of time and step-based physical activity metrics and predominantly includes white women of higher socioeconomic status. Being observational, it cannot establish causality. Looking forward, Hamaya plans to conduct a randomised controlled trial to delve deeper into the relationship between different exercise metrics and health outcomes.
More information: Rikuta Hamaya et al, Time- vs Step-Based Physical Activity Metrics for Health, JAMA Internal Medicine. DOI: 10.1001/jamainternmed.2024.0892
Journal information: JAMA Internal Medicine Provided by Brigham and Women’s Hospital
