Women’s Physical Activity Levels are Less Variable Than Men’s, Study Says

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Women’s physical activity levels are less variable than men’s, according to a new study published in the Journal of Medical Internet Research. What’s more, women’s hormonal cycles did not have a noticeable impact on physical activity levels.

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 under-represented 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 had 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 analyzed 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.

This study was funded under MTEC solicitation MTEC-20-12-Diagnostics-023 and the USAMRDC under the Department of Defense (#MTEC-20-12-COVID19-D.-023). The #StartSmall foundation (#7029991) and Oura Health Oy (#134650) also provided funding for this work.

Sex Differences in the Variability of Physical Activity Measurements Across Multiple Timescales Recorded by a Wearable Device: Observational Retrospective Cohort Study

University of California San Diego
Kristin J Varner, Shu Chien-Gene Lay Department of Bioengineering
Lauryn Keeler Bruce and Severine Soltani, Department of Bioinformatics and Systems Biology
Benjamin L Smarr, Shu Chien-Gene Lay Department of Bioengineering and Halıcıoğlu Data Science Institute
Subhasis Dasgupta, Ilkay Altintas and Amarnath Gupta, San Diego Supercomputer Center

University of California San Francisco
Wendy Hartogensis, Frederick M Hecht, Anoushka Chowdhary, Leena Pandya and Ashley E Mason, Osher Center for Integrative Health

The City University of New York
Stephan Dilchert, Department of Management, Zicklin School of Business, Baruch College