Sedentary Behaviour and Physical Activity in New Zealand Children : Intervention and measurement

Abstract

Background: Increasing physical activity and decreasing sedentary behaviour is important for the prevention and treatment of childhood obesity. Interventions to decrease sedentary behaviour (primarily sedentary screen-time) in children have had success in reducing screentime, increasing physical activity and improving body composition. Active video games, where players physically interact with on-screen images, are a promising intervention for reducing sedentary behaviour and increasing physical activity. However, there is a dearth of intervention research. Furthermore, research is limited by difficulties in accurately measuring these behaviours. Aim: To examine new approaches for intervention in, and measurement of, sedentary behaviour and physical activity in New Zealand children. Method: Two complementary studies were undertaken. The first was a large (n=322) randomised controlled trial that examined the effect of a 24 week active video games intervention on physical activity, sedentary behaviour and body composition in overweight and obese children. The second was a validation (n=32) of a self-report tool used to quantify daily energy expenditure, sedentary behaviour and physical activity in children. Doubly labelled water and accelerometry were used as the validation standards for energy expenditure and behaviour, respectively. Results: The first study found a significant treatment effect for body mass index over 24 weeks (-0.24kg/m2, 95% CI -0.44 to -0.05, p=0.02), favouring the intervention group. Overall levels of physical activity and sedentary behaviour did not change; however intervention participants reported playing more active video games (10.03 minutes, 95% CI 6.26. to 13.81, p<0.0001), and less sedentary video games (-9.39 minutes, 95% CI -19.38 to 0.59; p=0.07) than control. In the second study, the self-report tool indicated moderate validity for the assessment of total daily energy expenditure (rho=0.70, p<0.0001) and activity-related energy expenditure (rho=0.54, p=0.001) compared to the criterion standard of doubly labelled water. Compared to accelerometry, the self-report tool indicated moderate validity for the assessment of time spent in physical activity (rho=0.42, p=0.02) and weak validity for the assessment of time spent in sedentary behaviour (0.20, p=0.30). Conclusion: Active video games may be useful to promote a healthy weight in overweight or obese children. The self-report tool may be used in future sedentary behaviour intervention research.