Background: In Scotland, an estimated 20 percent of children 11 to 12 years of age and 10 percent of children four to five years of age are obese. Because more than 90 percent of young children in Scotland attend pre-school, Reilly and colleagues designed a preschool-based physical activity program for children four to five years of age with the goal of reducing obesity.

The Study: Around 500 children attending 36 preschools took part in the program. The preschools were paired by size, type, and socioeconomic status of the neighborhood served to provide a group of 18 intervention preschools, each with a matched control. Children in the intervention preschools took part in three 30-minute sessions of physical activity every week for 24 weeks. Posters were displayed in the intervention schools to raise awareness and encourage physical activity, and the children's families received health education materials on ways to increase physical activity at home. No new activities or health education materials were used in the control preschools.

The primary outcome was body mass index of participating children at six and 12 months after the intervention. Other outcomes measured included patterns of physical activity, sedentary behavior, and performance in fundamental movement skills. The research assistants who assessed outcomes were blinded to the study allocation of each preschool.

Results: Data were available on 481 children (88 percent) at six months and 504 children (93 percent) at the 12-month follow-up. At both assessments, group allocation had no impact on body mass index, levels of physical activity, or time spent in sedentary behavior. The control group showed a marginally significant increase in time spent in moderate or vigorous physical activity. Conversely, children in the intervention group improved fundamental movement skills significantly more than children in control preschools. This effect was greater for girls than for boys.

Conclusion: The authors conclude that this program to increase physical activity resulted in improvement in motor skills of children four to five years of age but had no demonstrable impact on obesity. They suggest that the program may have provided inadequate levels of physical activity to produce a measurable effect, and that several factors may need to be addressed simultaneously to impact body mass index. They suggest that future intervention programs for obesity in early childhood should incorporate attention to diet, more behavioral approaches, and greater involvement of parents.