Bristol girls dance project (BGDP): protocol for a cluster randomised controlled trial of an after-school dance programme to increase physical activity among 11-12 year old girls

Background: Many children do not meet current UK physical activity (PA) guidelines. Girls are less active than boys throughout childhood, and the age-related decline in PA, particularly from early adolescence, is steeper for girls than for boys. Dance is the favourite form of PA among UK secondary school aged girls. Delivering dance sessions after school could make a significant contribution to girls' PA. Therefore, after-school dance sessions may be an appropriate and cost-effective activity through which adolescent girls' PA levels can be increased. Design: Two-arm cluster randomised control trial and economic evaluation conducted in 18 secondary schools across the greater Bristol area. All Year 7 girls in participating schools will receive a 'taster' dance session and subsequently be invited to participate in the project. There is space for up to 33 girls to participate in each school. Schools will be randomly assigned in equal numbers to intervention or control arms after baseline data has been collected. The nine intervention schools will receive a 20 week after-school dance-based intervention, consisting of 40 x 75 minute sessions, delivered by external dance instructors. Control schools will not receive the dance intervention. All measures will be assessed at baseline (time 0), at the end of the intervention period (time 1) and six months after the intervention has ended (time 2). Our primary interest is to determine the effectiveness and cost-effectiveness of the intervention to affect the objectively-assessed (accelerometer) mean weekday minutes of moderate-to-vigorous PA (MVPA) accumulated by Year 7 girls one year after the baseline measurement (time 2). Discussion: This paper describes the protocol for the Bristol Girls Dance Project cluster randomized controlled trial and economic evaluation, which is attempting to increase MVPA among Year 7 girls in UK secondary schools.