This project of the Columbia, Mo., Active Living by Design grant program evaluated the physical activity levels of children participating in a school-wide walking school bus (WSB) program at three elementary schools. Walking to school is a good way for children to get moderate- to vigorous-intensity physical activity. But safety concerns sometimes limit children from walking unattended to school.

In Columbia in August 2007, 1,000 children were given a flyer inviting them to participate in the WSB program. Children who self-selected received accelerometers. Researchers collected data on body mass index, television habits and other demographics from 38 WSB participants and 39 nonparticipants.

No differences were observed in 7-day physical activity measures between WSB participants and nonparticipants. It is possible, the authors concede, that exposure to the promotional information on the WSB by participants and nonparticipants alike, influenced the physical activity of both groups of children.

Other studies have shown that physical activity declines in children between the ages of 12 and 18 years. In this study, when researchers looked at the relationship of moderate- to vigorous-intensity physical activity and age, they found that the slope of the regression line was steeper in those children not participating in the WSB program.