Age-related changes in types and contexts of physical activity in middle school girls.

BACKGROUND Because girls are less physically active than boys, it is important to understand the types of activities preferred by girls, and changes in those preferences over time, in order to design effective physical activity interventions. PURPOSE To describe developmental trends in participation in specific forms of physical activity in 6th- and 8th-grade girls. METHODS Data for this study are from the Trial of Activity for Adolescent Girls. Self-reported physical activity, anthropometric, and demographic data were collected from random cross sections of 6th-grade girls in 36 middle schools in six U.S. communities. The same data were collected 2 years later from random cross sections of 8th-grade girls, as well as in previously measured 6th-grade girls who remained in the schools. Analyses were conducted with SAS using mixed-model ANOVAs to determine differences between 6th- and 8th-grade girls. Data were collected in 2002-2003 and 2004-2005 and analyzed in 2008-2009. RESULTS The top physical activities reported by 6th- and 8th-grade girls were similar. Of the top 13 activities reported by 6th- or 8th-grade girls, 8th-grade girls reported participating in more 30-minute blocks for ten of the activities and were more likely to report participating as part of an organized program. CONCLUSIONS The activities reported by 6th- and 8th-grade girls were similar, but the way they participated in them changed from 6th to 8th grade. Eighth-grade girls were more likely to participate in activities that are often part of school-based team sports, and the time of participation in these activities was greater. Interventions to increase physical activity in adolescent girls should be informed by the factors that influence their participation in organized school sports programs and community-based activities that promote physical activity.