Adequate physical activity is the cornerstone of a healthy lifestyle. Being physically active can help to build muscle, strengthen bones, and manage weight. Despite the benefits, many worldwide fall short of physical activity recommendations. Researchers from Stanford University have embarked on a unique mission to compile physical activity data from around the world in order to create a picture of global activity.
A total of 717,527 individuals from 111 countries were included in their analyses. Step count information was obtained from the Argus smartphone application. By using the smartphone as a tool for data collection, the team was able to bypass the typical pitfalls of physical activity research. Most studies of this kind rely on self-reported activity which can often be biased or inaccurate. Others utilize technology like accelerometers that can quickly become expensive when scaling up the sample size. Smartphones are becoming more and more common, even in the developing world. Using these devices and the application to provide them with data allowed the researchers to gather information from across the globe. As with any method of data collection, this technique was not foolproof. Those who did not have access to a Smartphone could not be included. In addition, the application requires the user to have their phone with them in order to count their steps leaving out any activity during which it is unrealistic to carry a phone (i.e. playing sports, swimming, etc.).
As would be expected, investigators found that some countries are more active than others. For example, Japan was on the higher end with an average of 5,846 steps per day, and Saudi Arabia was on the lower end of the spectrum with an average of 3,103 steps per day. The United States ranked somewhere in the middle with an average step count of 4,774. One might assume that a country’s level of activity would directly relate to rates of obesity in that country. While that is true, it does not tell the whole story. Researchers noticed that not only did average step count vary between countries, but so did the variance of the responses. This means that in some countries, like Japan, the step counts from the sample fit within a narrow range. Others, like Saudi Arabia, had a wide range of responses that stretched out wide around the average. Countries like this have large activity inequity meaning that some people are highly active while others, women in particular, fall well below the average. After further examination of these characteristics, researchers determined that activity inequity was a better predictor of obesity than average step count across gender, age, and income.
The higher the activity inequity of a country, the higher the rates of obesity. This opens a few avenues for intervention. Researchers looked at several cities within the United States and rated them on “walkability.” They found that if a city was more walkable, it had lower activity inequity. They also found that the walkability of a city had the greatest impact on those who needed it most, like women. This indicates that making it easier to get around on foot helps to encourage activity in those who would otherwise be less active.
This information has major public health implications. This is a prime example of something that can be done at the local level and have widespread impacts. By making cities more walkable, citizens who are the most vulnerable to inequity may be encouraged to increase their activity and help to narrow the gap. It brings more nuance into the discussion of how physical activity impacts health. We know that regular activity is important for the health of the individual, but this study brings to the light the importance of staying active for our global community.
Source:
Althoff, T., Hicks, J. L., King, A. C., Delp, S. L., & Leskovec, J. (2017). Large-scale physical activity data reveal worldwide activity inequality. Nature, 547(7663), nature23018.
