Feasibility of a school-based peer-led high-intensity interval training intervention: the Young Fitness Leaders project

TL;DR

This study tested if older students can lead high-intensity workouts for younger students in schools, finding it feasible but needing improvements for effectiveness.

Contribution

The study introduces a peer-led model for delivering high-intensity interval training in schools, addressing scalability issues.

Findings

Peer-led HIIT was feasible with high recruitment and retention rates.

Intervention heart rates were below target, suggesting delivery inconsistencies.

Acceptability was positive, but effectiveness may be limited without improved delivery.

Abstract

While school-based high-intensity interval training (HIIT) has demonstrated efficacy for improving adolescents’ physical and mental health, interventions have largely been researcher-led, which limits scalability. This could be resolved via peer-led programmes, whereby older pupils (i.e., peer-leaders) deliver HIIT to younger pupils (i.e., peer-recipients). We aimed to explore the feasibility of a school-based peer-led HIIT intervention.

Using a non-randomised controlled trial design, 44 Year 7 pupils (aged 12.1 ± 0.3 years [mean ± SD]) were recruited from one school in North East England, with 21 (8 girls) allocated as peer-recipients to an 8-week HIIT intervention, and 23 (17 girls) as controls. Five Year 12–13 pupils (aged 17.3 ± 0.4 years) were recruited as peer-leaders and received training on school-based HIIT based on boxing and whole-body exercises. Peer-leaders then delivered twice weekly HIIT sessions during morning tutor time. Primary outcomes were recruitment, retention, attendance and acceptability (explored in post-intervention focus groups with peer-recipients, peer-leaders and teachers). Secondary outcomes included intervention fidelity (via researcher field note observations and heart rate monitoring), and preliminary impact on physical fitness and psychological outcomes.

Recruitment was 72% (21/29 eligible pupils), 74% (23/31) and 42% (5/12) for peer-recipients, controls and peer-leaders, respectively. All control participants completed the study; one peer-leader left the school, and two peer-recipients withdrew (94% overall retention). Intervention attendance (expressed as percentage of scheduled sessions) was 73 ± 31%. The intervention was generally well-received by peer-recipients, peer-leaders and teachers. The mean peak heart rate across all repetitions was 76% of age-predicted maximal, with a between- and within-participant variability of 6% points and 8% points, respectively. For the physical fitness and psychological outcomes, intervention effect directions were inconsistent and effect estimates imprecise.

Peer-led HIIT may represent a scalable and feasible school-based physical activity model from a recruitment, retention, attendance and acceptability perspective. However, intervention heart rates and session observations suggest HIIT activities were not always delivered and performed as intended, which could limit intervention effectiveness in larger-scale trials. Future iterations of peer-led HIIT programmes should focus on refining intervention delivery by providing an enhanced training and support package for peer-leaders.

The trial was registered on ISRCTN, the UK’s Clinical Study Registry on 6th March 2023 (https://www.isrctn.com/ISRCTN89390191). The trial registration number is ISRCTN89390191.

The online version contains supplementary material available at 10.1186/s12889-026-26543-w.

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