Impact of high-intensity interval training including Indigenous narratives on adolescents’ mental health: a cluster-randomised controlled trial

Objectives: We investigated the efficacy of teacher‐delivered high‐intensity interval training (HIIT) with Indigenous narrative options on the mental health of school students in low–mid socioeconomic areas, compared to standard curriculum physical education practice. Methods: A cluster‐randomised controlled trial was conducted in eight schools (N=368, age range 11–13 years) over 16 weeks. The primary outcome was the Strengths and Difficulties Questionnaire (SDQ) score. Generalised linear mixed models, controlling for the SDQ at baseline were applied, expressed as β, 95% confidence intervals, standardised effect, and p‐value. Focus groups elicited experiences with participating in and delivering the intervention. Results: There were no clear effects for SDQ total score (β ‐0.15, CI ‐0.98 ‐ 0.67, SE 0.42, p=0.714). Teachers did not deliver the Indigenous narrative options consistently owing to the perceived preparation needed and lack of confidence. Conclusions: HIIT delivered in this manner had no effect on self‐perceived psychological difficulty or mental wellbeing in a cohort of young adolescents. Implications for public health: Future research should continue to explore opportunities to improve mental wellbeing via physical activity, but HIIT should not be implemented as a universal intervention for mental health gains alone. Teachers need more support to utilise Indigenous narratives as part of HIIT delivery.