title: A cluster randomised controlled trial to investigate the effectiveness and cost effectiveness of the 'Girls Active' intervention: a study protocol.
abstract: BACKGROUND
  Despite the health benefits of physical activity, data from the UK suggest that a large proportion of adolescents do not meet the recommended levels of moderate-to-vigorous physical activity (MVPA). This is particularly evident in girls, who are less active than boys across all ages and may display a faster rate of decline in physical activity throughout adolescence. The 'Girls Active' intervention has been designed by the Youth Sport Trust to target the lower participation rates observed in adolescent girls. 'Girls Active' uses peer leadership and marketing to empower girls to influence decision making in their school, develop as role models and promote physical activity to other girls. Schools are provided with training and resources to review their physical activity, sport and PE provision, culture and practices to ensure they are relevant and attractive to adolescent girls.
  
  
  METHODS
  This study is a two-arm cluster randomised controlled trial (RCT) aiming to recruit 20 secondary schools. Clusters will be randomised at the school level (stratified by school size and proportion of Black and Minority Ethnic (BME) pupils) to receive either the 'Girls Active' intervention or carry on with usual practice (1:1). The 20 secondary schools will be recruited from state secondary schools within the Midlands area. We aim to recruit 80 girls aged 11-14 years in each school. Data will be collected at three time points; baseline and seven and 14 months after baseline. Our primary aim is to investigate whether 'Girls Active' leads to higher objectively measured (GENEActiv) moderate-to-vigorous physical activity in adolescent girls at 14 months after baseline assessment compared to the control group. Secondary outcomes include other objectively measured physical activity variables, adiposity, physical activity-related psychological factors and the cost-effectiveness of the 'Girls Active' intervention. A thorough process evaluation will be conducted during the course of the intervention delivery.
  
  
  CONCLUSIONS
  The findings of this study will provide valuable information on whether this type of school-based approach to increasing physical activity in adolescent girls is both effective and cost-effective in the UK.
  
  
  BACKGROUND
  ISRCTN10688342. Registered 12 January 2015.
authors.affiliation: Diabetes Research Centre, University of Leicester, Leicester, UK. ce95@le.ac.uk.|NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, Leicester, UK. ce95@le.ac.uk.
authors.forename: C L
authors.initials: CL
authors.lastname: Edwardson
authors.affiliation: Diabetes Research Centre, University of Leicester, Leicester, UK. dh204@le.ac.uk.|NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, Leicester, UK. dh204@le.ac.uk.
authors.forename: D M
authors.initials: DM
authors.lastname: Harrington
authors.affiliation: Diabetes Research Centre, University of Leicester, Leicester, UK. ty20@le.ac.uk.|NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, Leicester, UK. ty20@le.ac.uk.
authors.forename: T
authors.initials: T
authors.lastname: Yates
authors.affiliation: Diabetes Research Centre, University of Leicester, Leicester, UK. dhm6@le.ac.uk.|NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, Leicester, UK. dhm6@le.ac.uk.
authors.forename: D H
authors.initials: DH
authors.lastname: Bodicoat
authors.affiliation: Diabetes Research Centre, University of Leicester, Leicester, UK. kk22@le.ac.uk.|NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, Leicester, UK. kk22@le.ac.uk.
authors.forename: K
authors.initials: K
authors.lastname: Khunti
authors.affiliation: School of Sport, University of Stirling, Scotland, UK. Trish.Gorely@stir.ac.uk.
authors.forename: T
authors.initials: T
authors.lastname: Gorely
authors.affiliation: NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, Leicester, UK. L.B.Sherar@lboro.ac.uk.|School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, UK. L.B.Sherar@lboro.ac.uk.
authors.forename: L B
authors.initials: LB
authors.lastname: Sherar
authors.affiliation: Centre for Health Economics and Medicines Evaluation, Bangor University, Bangor, UK. r.t.edwards@bangor.ac.uk.
authors.forename: R T
authors.initials: RT
authors.lastname: Edwards
authors.affiliation: Youth Sport Trust, Leicestershire, UK. chris.wright@youthsporttrust.org.
authors.forename: C
authors.initials: C
authors.lastname: Wright
authors.affiliation: Diabetes Research Centre, University of Leicester, Leicester, UK. mlh31@le.ac.uk.
authors.forename: K
authors.initials: K
authors.lastname: Harrington
authors.affiliation: Diabetes Research Centre, University of Leicester, Leicester, UK. Melanie.davies@uhl-tr.nhs.uk.|NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, Leicester, UK. Melanie.davies@uhl-tr.nhs.uk.
authors.forename: M J
authors.initials: MJ
authors.lastname: Davies
mesh_terms: D000293:Adolescent; D002648:Child; D016000:Cluster Analysis; D003362:Cost-Benefit Analysis; D015444:Exercise; D005260:Female; D006293:Health Promotion / Q000191:economics* / Q000592:standards*; D006801:Humans; D009765:Obesity / Q000517:prevention & control; D017063:Outcome Assessment, Health Care; D010379:Peer Group; D012107:Research Design; D012574:Schools; D013177:Sports; D006113:United Kingdom