Global increases in sedentary behavior – like sitting or lying down – are worrisome for public health as they may be harbingers of increased mortality and morbidity, such as obesity and high blood pressure. According to the World Health Organization (WHO), nearly 25% of adults and more than 80% of adolescents across the world are not physically active enough. WHO estimates that nearly 5 million deaths could be prevented each year if more people were active. 

Studying physical activity behaviors among young children may be key to understanding sedentary behavior in adulthood and beyond. Early childhood is a critical stage of development – during this time, kids are learning from their environments and beginning to develop autonomy in play. Studies of humans and animals find that physically active children are more likely to remain active as they grow up, suggesting that early nurturing of physical activity can lead to an active lifestyle for life.

More research is needed to understand the factors that influence young children’s sedentary behaviors. Currently, the scientific evidence is relatively scarce and inconsistent. Furthermore, there are limited case studies. Most take place in countries that have four seasons and experience extremes in weather conditions (for example, Australia, Canada, and the UK). 

To advance what we already know, my colleagues and I investigate factors correlated with sedentary time for over 500 children who are 4 to 6 years old in Mexico City. The children are participants in PROGRESS (Programming Research in Obesity, GRowth, Environment, and Social Stress), an ongoing cohort study funded by the National Institutes of Health that is analyzing children’s development in Mexico. In our recently published study, we find that air temperature, daylight, and rain are significantly correlated with sedentary time; and our statistical models were adjusted for demographic characteristics. Increases in air temperature and daylight are linked to a decline in sedentary time, suggesting that warmer weather and longer daylight hours are weather conditions that encourage more physical activity and provide children with more time to play outside. An increase in rain is associated with an increase in sedentary time. Rain may curb outdoor activity, thus constraining opportunities for physical activity and promoting sedentary behavior. 

We improve on the current science by using objective and more precise measures of sedentary time and weather conditions than most other studies. It is common to survey people about their physical activity, but this is subject to response bias and memory recall problems. Our study avoids such issues by utilizing accelerometers to collect physical activity data. We also developed a temperature model using data from meteorological stations and satellites – a first for the region. Our data and code are available online.

We recognize that the causes of sedentary behavior are multifaceted and go beyond weather conditions to include social norms and contexts. However, while our work represents a small piece of the puzzle, our study in a temperate climate nonetheless reveals that even small weather differences are linked to changes in children’s sedentary time. There is a clear need for interventions and policies that deter sedentary behavior when weather conditions discourage physical activity. One recommendation is to develop better infrastructure for active transportation and to build indoor play spaces that provide protection against rain and cold temperatures. 

Our findings provide valuable baseline trends upon which future research can build on. As the PROGRESS team tracks the physical activity levels of kids over time, we can use that data to better identify the causes of children’s sedentary behaviors, ascertain critical early intervention opportunities, and promote the healthy development of kids from early childhood into adulthood. 

The feature image is from Pexels.