Stanford University researchers, in a large-scale study funded by the National Institutes of Health, report that they have tracked the physical activity by population in more than 100 countries, using daily step data from participants’ smartphones.

Results from the study, published recently in Nature, reveal targets for obesity prevention and the wisdom of walkable communities, according to a media release from NIH/National Institute of Biomedical Imaging & Bioengineering.

Participants whose data contributed to the study subscribed to the Azumio Argus app, a free application for tracking physical activity and other health behaviors.

In their study, Scott L. Delp, Ph.D., James H. Clark Professor of Bioengineering and director of the Mobilize Center at Stanford University, and colleagues analyzed 68 million days of minute-by-minute step recordings from 717,527 anonymous users of the smartphone app. Participation spanned 111 countries, but the researchers focused their study on 46 countries, each with at least 1,000 users. Of those, 90% of users were from 32 high-income countries and 10% were from 14 middle-income countries.

In addition to the step records, the researchers accessed age, gender, and height and weight status of users who registered the smartphone app, the release explains.

Globally, the average user recorded about 5,000 steps per day. The smartphone data reflected the degree of difference, or inequality, for activity among people within a given country. By comparing countries with more uniform activity patterns and those with unequal activity, certain patterns and health dynamics emerged. For instance, countries with the greatest activity inequality are also the countries with the greatest obesity problem. Individuals in the five countries with the greatest activity inequality are nearly 200% more likely to be obese than individuals from the five countries with the lowest activity inequality.

The authors suggest that this inequality is an important target for obesity intervention. Using a computer simulation, they showed that targeted interventions could result in up to a four times greater reduction in obesity than non-targeted approaches, the release continues.

The researchers suggest that countries with greater activity variation also have a larger proportion of inactive women. In addition, they suggest that the prevalence for obesity increases faster for females than males as population-wide activity decreases.

Making improvements in a city’s walkability could reduce activity inequality and the activity gender gap, they add.

Data from 69 US cities indicate that higher walkability scores are associated with lower activity inequality, per the release. However, according to the researchers, women recorded comparatively less activity than men in places that are less walkable.

“These results reveal how much of a population is activity-rich, and how much of a population is activity-poor,” Delp says, in the release. “In regions with high activity inequality there are many people who are activity poor, and activity inequality is a strong predictor of health outcomes.”

[Source(s): NIH/National Institute of Biomedical Imaging & Bioengineering, Science Daily, Newswise]