Author(s): WESTON, K., BURN, N., GALNA, B., WESTON, M., GORDON, A., BASTERFIELD, L., Institution: UNIVERSITY OF STRATHCLYDE, Country: UNITED KINGDOM, Abstract-ID: 2142

INTRODUCTION:
Despite being an efficacious way of improving aspects of child and adolescent physical and mental health, school-based high-intensity interval training (HIIT) interventions are typically delivered by researchers, which limits scalability. This problem could be solved via a peer-led programme, whereby older school pupils deliver HIIT sessions to younger pupils. So, we aimed to explore the feasibility of delivering a school-based peer-led HIIT intervention in North East England.
METHODS:
Using a non-randomised controlled trial design, 44 Year 7 pupils (aged 12.1 ± 0.3 years [mean ± SD]) were recruited from one secondary school, with 21 pupils (8 girls) assigned to a peer-led 8-week HIIT intervention and 23 Year 7 pupils (17 girls) to the control condition. Five Year 12/13 pupils (aged 17.3 ± 0.4 years) were recruited as peer-leaders and received in-person and virtual training on the delivery of school-based HIIT using boxing and whole-body exercises. These pupils then delivered HIIT sessions twice weekly during morning tutor time (0830-0845 hours). Sessions initially were 4 x 45 s maximal effort bouts, interspersed with 60 s rest. Each fortnight, bout length increased by 5 seconds. Primary outcomes were recruitment, retention, and intervention attendance. Intervention fidelity was examined via heart rate monitoring with 85% of age-predicted maximal heart rate the criterion for high-intensity exercise. Secondary outcome measure was the post-intervention change in 20m shuttle-run test (20m SRT) performance. Intervention fidelity was examined via mixed linear modelling and the intervention effect on 20m SRT via analysis of covariance.
RESULTS:
Recruitment was 72% (21/29 eligible pupils) for intervention participants, 74% (23/31) for controls, and 30% (5/12) for peer-leaders. All peer-leaders and control participants completed the study; in the intervention group two boys dropped out. Intervention attendance (expressed as percentage of available intervention sessions [n=16] was 73%. Mean intervention heart rate was 76.3 (95% Confidence Interval 73.2, 79.3) % of age-predicted maximal heart rate with a within- and between-participant variability of 5.9 (4.0, 8.5) % points and 9.8 (9.2, 10.0) % points, respectively. The proportion of intervention repetitions (n=508) meeting our high-intensity criterion was 26 (22, 30) % (bout 1: 19 [13, 27]) %, bout 2: 22 [16, 30] %, bout 3: 27 [21, 36] %, bout 4: 35 [27, 43] %). The intervention effect (intervention minus control) was imprecise (2; -2, +7 shuttles, p = 0.323, d = 0.16; -0.16, 0.47).
CONCLUSION:
Peer-led HIIT may represent a scalable and feasible school-based exercise model from a recruitment, retention and attendance perspective. However, the intensity of the HIIT sessions was often below our high-intensity criterion, suggesting intervention delivery and fidelity could be improved. This could be addressed by providing more training and support to the peer-leaders before and during the intervention period.