Prior research has shown that a significantly lower proportion of women do enough recommended daily physical activity when compared to men, despite the well-known benefits of exercise. Research could help find the reasons for these disparities and ways to close that gap, but women are underrepresented in sports and exercise studies. This is due in part to concerns that menstrual cycles would introduce too much variability in the data. Even though that reasoning is commonly used to restrict studies to men, the assertion has never been tested. Researchers from the University of California, San Diego, the University of California, San Francisco and the City University of New York wanted to find out if these concerns were based on fact.

The team analysed data gathered from the Oura ring, a wearable device that tracks physical movement and records skin temperature and sleep patterns, among other data. The ring was worn continuously over 206 days by 596 individuals, equally divided between males and females, ages 20 to 79. They found that women’s physical activity levels—measured by Oura’s minute-to-minute metric MET, which is similar to other devices’ step counting function—were less variable and so more predictable than men’s across many time scales. In addition, physical activity levels for individuals with menstrual cycles were not more variable than the levels of those without cycles.

While researchers found that overall levels of activity did not change on the weekends, there was a subgroup of men whose activity levels increased dramatically on the weekends. Likewise, they found a subgroup of women whose levels of activity decreased on the weekend. Older age groups tended to have the least variable levels of physical activity.

“The exclusion of people from [physical activity] research based on their biological sex, age, the presence of menstrual cycles, or the presence of weekly rhythms in physical activity is not supported by our analysis,” the researchers write. The authors hope this will encourage those interested in studying physical activity to include people of all sexes, ages and lifestyles, as these variables do not appear to interfere with statistical assessment.