Effect of Changing Sedentary Behavior in Youth
Condition: Obesity
MeSH terms: Obesity
Study type: Interventional

Summary: 
      The primary aim is to examine how reduction in sedentary behaviors influences physical
      activity and energy intake.
    

Detailed description: 
      Many youth find television, videos and computer games to be very reinforcing, and they choose
      to be sedentary rather than physically active. Sedentary behaviors can influence energy
      balance and body weight by reducing physical activity and increasing energy intake. Research
      from our laboratory has shown that reducing sedentary behavior can increase physical activity
      and decrease energy intake, but there is substantial variability in the response of youth to
      reductions in sedentary behavior. The present proposal is designed to extend our research and
      explore theoretical models that may help understand why youth vary in their response to
      increase physical activity when targeted sedentary behaviors are reduced. We hypothesize that
      the increase in physical activity when sedentary behaviors are reduced is related to the
      relative reinforcing value (RRV) of physical activity to sedentary behaviors. The RRV of
      physical activity is a measure of the motivation to be active in youth, and overweight youth
      who are inactive find physical activity relatively less reinforcing than less overweight
      youth. We predict that RRV of physical activity will be positively related to the
      substitution of total physical activity and physical activity in the moderate to vigorous
      intensity range for sedentary behaviors when targeted sedentary behaviors are reduced. To
      test this hypothesis, we will study 60 overweight and at risk for overweight 8-12 year-old
      youth who differ in the RRV of physical activity to sedentary behavior, with equal numbers of
      boys and girls, in 3 phases: baseline, and reduce television watching from baseline by 25
      percent and 50 percent. Each phase will be implemented for three weeks. Order of experimental
      phases will be counterbalanced across subjects. It is also predicted that reducing sedentary
      behavior will reduce energy intake and dietary fat intake, and the reduction in energy intake
      will be greatest for youth with stronger association between eating with television watching
      and other targeted sedentary behaviors. Liking and outcome expectancy of physical activity
      will be studied as additional predictors of substitution of physical activity for reductions
      in sedentary behaviors. Developing a better understanding of why obese youth increase
      physical activity or decrease energy intake when sedentary behaviors are reduced is important
      for the treatment of pediatric obesity.
    

Intervention name(s): Television reduction device
Intervention type(s): Device
Intervention description(s): A TV allowance helps turn off the television when the time limits have been met.
Intervention model: Sequential Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: physical activity; relative reinforcing value; sedentary behavior; obesity