Leahy 2019.

Study characteristics
Methods	Study design: cluster‐RCT
Participants	School inclusion criteria: — School exclusion criteria: — Student inclusion criteria: students in Grade 11 at study schools who did not have an injury or illness that would preclude their participation in high‐intensity activity as outlined in the participant information and consent form (e.g. existing physical injury) Student exclusion criteria: — Setting: school Age group: adolescents Gender distribution: females and males Country where trial was performed: Australia
Interventions	Intervention: Burn2Learn, a 14‐week multi‐component high‐intensity interval training intervention to improve older adolescents’ physical and mental health. Participants were prescribed 3 high‐intensity interval training sessions/week, for 14 weeks. Teachers were asked to offer at least 2 opportunities/week for high‐intensity interval training during class time, with the ultimate target of students performing 3 sessions/week (i.e. 1 self‐directed session outside of class). Any additional high‐intensity interval training sessions performed by participants were reported individually to the school champion to monitor session adherence. High‐intensity interval training sessions comprised a brief 2‐minute warm‐up, followed by 8 to 16 minutes of high‐intensity interval training, followed by a 2‐minute cool‐down (12 to 20 minutes total). Sessions were performed individually, in pairs, or in small groups. Participants were provided with pre‐designed high‐intensity interval training workouts that included a combination of aerobic‐based (e.g. shuttle runs) and resistance‐based (e.g. push‐ups) exercises designed to be performed using minimal space and equipment. Participants were able to select from the following high‐intensity interval training theme workouts: gym high‐intensity interval training, sport high‐intensity interval training, class high‐intensity interval training, dance high‐intensity interval training, combat high‐intensity interval training, and brain high‐intensity interval training. A full‐day professional learning workshop was provided for a school champion (i.e. teacher) and another member of staff to facilitate the Burn2Learn programme. The intervention included an introductory seminar for students, school‐based high‐intensity interval training sessions, parental videos, and an equipment and resource pack (including high‐intensity interval training task cards). Technique cards reinforcing correct technique were also provided to the intervention school and were used by the school champion during early weeks of the intervention. To encourage maintenance of the appropriate exercise intensity (i.e. > 85% maximum heart rate), participants were provided with heart rate monitors (Wahoo TICKR) during high‐intensity interval training sessions. Participants’ heart rates during sessions were viewed on smartphones utilising a commercially available group heart rate monitoring application (OnBeat) Comparator: a wait‐list control group participated in usual school activities and received the intervention following the post‐test assessment period Duration of intervention: 14 weeks Duration of follow‐up: 14 weeks Number of schools: 2 Theoretical framework: self‐determination theory
Outcomes	Fitness BMI Health‐related quality of life
Study registration	ACTRN12617000544370
Publication details	Language of publication: English Funding: non‐commercial funding (governmental organisation) Publication status: peer‐reviewed journal
Stated aim for study	"the objective of this study was to evaluate the impact of a teacher‐facilitated high intensity interval training program for older adolescents, embedded within the school day in regard to 4 domains of feasibility (i.e. recruitment, retention, adherence, and program satisfaction). Preliminary efficacy was evaluated by testing the effect of the high intensity interval training program on cardiorespiratory fitness, muscular fitness, and psychological health"
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote from publication: "the 2 schools were randomised to the Burn2Learn intervention group, or a wait‐list control group using a coin flip by an independent researcher not involved in the project following baseline assessments"
Allocation concealment (selection bias)	Low risk	Quote from publication: "the 2 schools were randomised to the Burn2Learn intervention group, or a wait‐list control group using a coin flip by an independent researcher not involved in the project following baseline assessments"
Blinding of participants and personnel (performance bias) All outcomes	High risk	Comment: not possible
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote from publication: "trained research assistants, who were blinded to group allocation, conducted assessments for the primary outcome. Assessors responsible for the collection of secondary outcomes were not blinded to group allocation"
Incomplete outcome data (attrition bias) Anthropometrics, Fitness	High risk	Comment: reasons for dropout not reported
Selective reporting (reporting bias)	High risk	Comment: PA not reported
Cluster RCT ‐ Recruitment bias	Low risk	Quote from publication: "the 2 schools were randomised to the Burn2Learn intervention group, or a wait‐list control group using a coin flip by an independent researcher not involved in the project following baseline assessments"
Cluster RCT ‐ Baseline imbalance	Low risk	Comment: baseline demographics were compared, and all groups were similar [author communication]
Cluster RCT ‐ Loss of clusters	Low risk	Comment: no clusters lost
Cluster RCT ‐ Incorrect analysis	High risk	Comment: no clustering accounted for in analysis