Does Physical Activity in Preschools Lower BMI?

Abstract

Source: Reilly JJ, Kelly L, Montgomery C, et al. Physical activity to prevent obesity in young children: cluster randomized controlled trial. BMJ. 2006;333:1041–1043; doi:10.1136/bmj.38979.623773.55Decreased physical activity and increased consumption of high-calorie foods have led to alarming levels of obesity in children. In Scotland in 2001, 10% of children aged 4 to 5 years and 20% of 11- to 12-year-old children were considered obese.1 To address this problem, these authors from the University of Glasgow and the Glasgow City Council Education Department conducted a cluster randomized, single-blinded controlled study to assess whether a program to increase physical activity in preschoolers would decrease their body mass index (BMI). The study was conducted over a 12-month period in 36 nursery schools in Glasgow; 545 children with a mean age of 4.2 years (SD 0.2) at the start of the study participated in the project. All 36 participating nursery schools were randomly allocated to an intervention or control group. The intervention consisted of: 1) a nursery school physical activity program with three 30-minute sessions each week over a 24-week period; and 2) parental educational literature. In addition, those nurseries randomly selected to receive the intervention had poster displays highlighting the importance of increasing physical activity. The primary outcome was BMI, which was determined at baseline, 6 months, and 12 months after implementation of the intervention. Secondary outcome measures included levels of physical activity and sedentary behavior, and performance of movement skills, which was assessed using a movement assessment battery.The only significant differences found were in fundamental movement skills on both individual and nursery cluster levels: children in the intervention group improved their motor skills more significantly than those in the control group. There were no significant effects of the intervention on BMI, physical activity, or sedentary behavior.Dr. Sriraman has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of a commercial product/device. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.The obesity epidemic cannot be ignored. Children are developing health problems that were previously considered to be adult health issues, such as noninsulin dependent diabetes mellitus and hypertension. This study contributes to our growing knowledge of what does and does not work. This preschooler intervention did not affect BMI but did lead to improvement in motor skills, which might boost confidence in physical capabilities and promote long-term physical activity.There are several limitations of this study. A 2-month follow-up may have been insufficient to detect differences in some outcomes. There were no standardized measurements regarding activity level. The rigor of the physical activity intervention may have been inconsistent, so the activity level may have been inadequate to affect BMI. The home intervention, which consisted of literature on health education, likely added little. Interventions in managing obesity and weight control involving behavioral change are more effective with family participation.2 Most important, the intervention addressed only physical activity; however, consumption of high-calorie foods may be a larger contributor to BMI.This study’s negative results should not discourage us from confronting this epidemic with more commitment to research and public policy initiatives: an ounce of prevention may be easier to achieve than a pound of cure.