Introduction This study assessed the feasibility and acceptability of FRESH (Families Reporting Every Step to Health), a theory-based child-led family physical activity (PA) intervention delivered online. We also assessed the preliminary effectiveness of the intervention on outcomes of interest and whether pre-specified criteria were met to progress to a full-scale definitive trial. Methods In a three-armed randomised pilot trial, 41 families (with a 7–11-year-old index child) were allocated to a: ‘family’ (FAM), ‘pedometer-only’ (PED), or a no-treatment control (CON) arm. The FAM arm received access to the FRESH website, allowing participants to select step challenges to ‘travel’ to target cities around the world, log their steps, and track progress as families virtually globetrot. FAM and PED arms also received family sets of pedometers. All family members could participate in the evaluation. Physical (e.g., fitness, blood pressure), psychosocial (e.g., social support), behavioural (e.g., objectively-measured PA), and economic (e.g., expenditure for PA) data were collected at baseline, 8- and 52-weeks. Results At 8- and 52-weeks, 98 and 88% of families were retained, respectively. Most children liked participating in the study (> 90%) and thought it was fun (> 80%). Compared to the PED (45%) and CON (39%) arms, a higher percentage of children in the FAM (81%) arm reported doing more activities with their family. Adults agreed that FRESH encouraged their family do more PA and made their family more aware of the amount of PA they do. No notable between-group differences were found for childrens’ minutes in moderate-to-vigorous PA. Sizeable changes of 9.4 (95%CI: 0.4, 18.4) and 15.3 (95%CI: 6.0, 24.5) minutes in moderate-to-vigorous PA was found for adults in the FAM group compared to those in the PED or CON groups, respectively. No other notable differences were found. Conclusion This study demonstrates feasibility and acceptability of the FRESH intervention. All progression criteria were at least partially satisfied. However, we failed to recruit the target sample size and did not find a signal of effectiveness on PA particularly long-term or in children. Further refinements are required to progress to a full-scale trial. Trial registration This study was prospectively registered (ISRCTN12789422) on 16/03/2016.

Background Less than 20% of adolescents globally meet recommended levels of physical activity, and not meeting these recommended levels is associated with social disadvantage and rising disease risk. The determinants of physical activity in adolescents are multilevel and poorly understood, but the school's social environment likely plays an important role. We conducted a cluster randomised controlled trial to assess the effectiveness of a school-based programme (GoActive) to increase moderate-to-vigorous physical activity (MVPA) among adolescents. Methods and findings Non-fee-paying, coeducational schools including Year 9 students in the UK counties of Cambridgeshire and Essex were eligible for inclusion. Within participating schools (n = 16), all Year 9 students were eligible and invited to participate. Participants were 2,862 13-to 14year-olds (84% of eligible students). After baseline assessment, schools were computerrandomised, stratified by school-level pupil premium funding (below/above county-specific median) and county (control: 8 schools, 1,319 participants, mean [SD] participants per school n = 165 [62]; intervention: 8 schools, 1,543 participants, n = 193 [43]). Measurement staff were blinded to allocation. The iteratively developed, feasibility-tested 12-week intervention, aligned with self-determination theory, trained older adolescent mentors and inclass peer-leaders to encourage classes to conduct 2 new weekly activities. Students and classes gained points and rewards for engaging in any activity in or out of school. The

Background Adolescent physical activity levels are low and are associated with rising disease risk and social disadvantage at increasingly early ages. We aimed to assess the effectiveness of a school-based programme (GoActive) to increase moderate-to-vigorous physical activity (MVPA) in adolescents.Methods In this cluster randomised controlled trial, non-fee-paying, co-educational schools including Year 9 students (aged 13-14 years) in Cambridgeshire or Essex, UK, were eligible for inclusion; within participating schools, all Year 9 students were eligible. Schools were computer-randomised (1:1) to either the control or intervention group, stratified by school-level pupil premium (below vs above county-specific median) and county (Cambridgeshire vs Essex). Measurement staff were masked to allocation; investigators were not masked because of necessary school contact. The iteratively developed, feasibility-tested and refined 12-week intervention trained older adolescents (mentors) and in-class peer leaders to encourage classes to undertake two new weekly activities. Training sessions consisted of an initial session between facilitators and mentors lasting at least 1 h followed by six 30 min meetings every week during the first six weeks and meetings approximately every 2 weeks thereafter. Mentors met with peer leaders weekly. Students and classes gained points and rewards for activity in and out of school. The primary outcome was mean daily minutes of accelerometerassessed MVPA at 10 months post-intervention, assessed in the complete case population (ie, all students who had a 10-month post-intervention measurement and [in the intervention group] wore the accelerometer) under the intentionto-treat principle, and in the per-protocol population (ie, students who also reported weekly class activities and logged points). Ethical approval was granted from the University of Cambridge Psychology Ethics Committee (PRE.126.2016). This study is registered with the International Standard Randomised Controlled Trials registry, number ISRCTN31583496. Findings Of 103 eligible schools, 16 enrolled in the study. 2862 Year 9 students were eligible, of whom 1319 were in the eight control schools (mean of 165 [SD 62] students per school) and 1543 were in the eight intervention schools (mean 193 [SD 43] per school; intraclass correlation coefficient=0•03 for school-level MVPA). 2167 (76%) of 2862 students had a 10-month post-intervention measurement; we analysed the primary outcome in 1874 participants (65%) due to expected low levels of accelerometer wear (871 [66%] in control schools; 1003 [65%] in intervention schools); analyses were adequately powered to detect an effect. At 10 months, time spent doing MVPA did not differ significantly between adolescents at intervention schools versus those at control schools (mean difference -1•91 min [95% CI -5•53 to 1•70]; p=0•32). In the per protocol population (285 students in intervention schools and 871 in control schools at 10 months), results were similar (mean difference -1•87 min [-6•80...