The elasticity of time: associations between physical activity and use of time in adolescents

The way an individual uses one's time can greatly affect his or her health. The purpose of this article was to examine the cross-sectional cross-elasticity relationships for use of time domains in a sample of Australian adolescents. This study analyzed 24-hour recall time use data collected using the Multimedia Activity Recall for Children and Adults (N = 2,200). Using simple linear regression, the authors calculated the difference in time devoted to a reference activity (i.e., screen time, sleep, or social) given 1 hour extra in the time devoted to a criterion activity (i.e., physical activity). The most elastic activities were screen time and school-related time. Every additional hour committed to physical activity was associated with 32 minutes less screen time. This relationship was more pronounced in obese adolescents (-56 minutes screen time) compared with normal (-31 minutes) and overweight (-27 minutes) adolescents. Promising behavior patterns exist, with screen time appearing as a highly elastic behavior