PT  - JOURNAL ARTICLE
AU  - David R Lubans
AU  - Jordan J Smith
AU  - Narelle Eather
AU  - Angus A Leahy
AU  - Philip J Morgan
AU  - Chris Lonsdale
AU  - Ronald C Plotnikoff
AU  - Michael Nilsson
AU  - Sarah G Kennedy
AU  - Elizabeth G Holliday
AU  - Natasha Weaver
AU  - Michael Noetel
AU  - Tatsuya T Shigeta
AU  - Myrto F Mavilidi
AU  - Sarah R Valkenborghs
AU  - Prajwal Gyawali
AU  - Frederick R Walker
AU  - Sarah A Costigan
AU  - Charles H Hillman
TI  - Time-efficient intervention to improve older adolescents’ cardiorespiratory fitness: findings from the ‘Burn 2 Learn’ cluster randomised controlled trial
AID  - 10.1136/bjsports-2020-103277
DP  - 2020 Dec 20
TA  - British Journal of Sports Medicine
PG  - bjsports-2020-103277
4099  - http://bjsm.bmj.com/content/early/2020/12/20/bjsports-2020-103277.short
4100  - http://bjsm.bmj.com/content/early/2020/12/20/bjsports-2020-103277.full
AB  - Background Cardiorespiratory fitness (CRF) is an important marker of current and future health status. The primary aim of our study was to evaluate the impact of a time-efficient school-based intervention on older adolescents’ CRF.Methods Two-arm cluster randomised controlled trial conducted in two cohorts (February 2018 to February 2019 and February 2019 to February 2020) in New South Wales, Australia. Participants (N=670, 44.6% women, 16.0±0.43 years) from 20 secondary schools: 10 schools (337 participants) were randomised to the Burn 2 Learn (B2L) intervention and 10 schools (333 participants) to the control. Teachers in schools allocated to the B2L intervention were provided with training, resources, and support to facilitate the delivery of high-intensity interval training (HIIT) activity breaks during curriculum time. Teachers and students in the control group continued their usual practice. The primary outcome was CRF (20 m multi-stage fitness test). Secondary outcomes were muscular fitness, physical activity, hair cortisol concentrations, mental health and cognitive function. Outcomes were assessed at baseline, 6 months (primary end-point) and 12 months. Effects were estimated using mixed models accounting for clustering.Results We observed a group-by-time effect for CRF (difference=4.1 laps, 95% CI 1.8 to 6.4) at the primary end-point (6 months), but not at 12 months. At 6 months, group-by-time effects were found for muscular fitness, steps during school hours and cortisol.Conclusions Implementing HIIT during curricular time improved adolescents’ CRF and several secondary outcomes. Our findings suggest B2L is unlikely to be an effective approach unless teachers embed sessions within the school day.Trial registration number Australian New Zealand Clinical Trials Registry (ACTRN12618000293268).