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Despite well-established benefits, the majority of young people around the globe are not sufficiently active. In many countries, including Australia, physical activity (i.e. physical education and school sport) is not mandatory in the final two years of high school (i.e. senior school years). The aim of this study was to assess the impact of a time-efficient physical activity intervention on senior school students' on-task behaviour and subjective vitality. This was a sub-study of the Burn 2 Learn (B2L) cluster randomised controlled trial, which included two cohorts. Participants for this sub-study (N = 221) were from 10 secondary schools (23 classes) located in New South Wales, Australia (Cohort 2). Teachers allocated to the B2L intervention group were provided with training, resources and support to facilitate the delivery of two high-intensity activity breaks per week during lesson time for five weeks. A wait-list control was used as comparison group. On-task behaviour was assessed at baseline and post-test, using a momentary time sampling procedure and expressed as a percentage of lesson time. At post-test, subjective vitality was assessed at the start and end of the lesson using a validated questionnaire. Significant group-by-time effects were observed for students' on-task behaviour in favour of the B2L group [adjusted mean difference = 19.3% of lesson time (95% CI, 0.8 to 37.8), p = 0.042, d = 0.43]. At post-test, significant group-by-time effects were observed for students' subjective vitality favouring the B2L group [adjusted mean difference = 0.67 units (95% CI, 0.3 to 1.0), p < 0.001, d = 0.36]. The B2L intervention was successful in improving senior school students' on-task behaviour and their subjective vitality. These findings highlight the potential academic benefits of re-allocating curriculum time to physical activity during the senior school years.

There is growing interest in identifying the mechanisms underpinning the effects of physical activity on executive functions (e.g. inhibitory control, cognitive flexibility) in children. Our study examined cardiorespiratory fitness, muscular fitness, and motor competence as potential mediators of this relationship. The study used baseline data from the Learning to Lead (L2L) cluster randomised controlled trial. In total, 675 children (7–11 years, 49.5% girls) completed measures of moderate-to-vigorous physical activity (MVPA), cardiorespiratory fitness, muscular fitness, motor competence, and executive functions. Structural equation modelling was used to examine the potential mediating roles of cardiorespiratory fitness, muscular fitness, and motor competence in the cross-sectional association between MVPA and executive functions. Cardiorespiratory fitness (β = 0.06, SE = 0.021, p = 0.004) partially mediated the association between MVPA and cognitive flexibility. Muscular fitness was a significant mediator of the association between MVPA and both inhibitory control (β = 0.03, SE = 0.014, p = 0.027) and cognitive flexibility (β = 0.06, SE = 0.021, p = 0.005). No significant mediated effects were found for motor competence. Our findings suggest cardiorespiratory and muscular fitness (but not motor competence) mediate the association between physical activity and executive functions in children. [ABSTRACT FROM AUTHOR]

Objectives: Late adolescence (15-19 years) is a period of heightened susceptibility to stress, but regular physical activity may attenuate reactivity to stressors. We aimed to explore the effects of physical activity intensity on older adolescents' stress-reactivity and self-reported mental health., Design and Methods: Three-arm randomised controlled trial in New South Wales, Australia (April-June 2021). Thirty-seven older adolescents (16.1 ± 0.2 years, 59.5 % female) were randomised to: i) non-active control (CON), ii) light-intensity physical activity (LPA), or iii) moderate-to-vigorous-intensity physical activity (MVPA). Physical activity groups participated in 2 x 20-min sessions/week for 6 weeks. Salivary cortisol (sCort) reactivity to induced stress was assessed using the Trier Social Stress Test for Groups and quantified as area under the curve (sCort AUC ; Primary outcome). Secondary outcomes included peak cortisol (sCort Peak ), subjective-reactivity, perceived stress, and non-specific psychological distress. Group differences were assessed using multiple linear regression and quantified using Cohen's d., Results: No statistically significant effects were observed for sCort AUC or sCort Peak and the pattern of effects for subjective-reactivity was inconsistent. Effects for self-reported mental health were also non-significant (p > .05 for all) but of meaningful magnitude, favouring LPA and MVPA over CON (d's = -0.38 to -0.54). Delivery fidelity was high, satisfaction was moderate-to-high, and there was no evidence of harm. However, recruitment, retention for sCort measures, and adherence were lower than expected., Conclusion: Suboptimal recruitment, retention, and adherence limited our ability to conclude on the effect of physical activity intensity on older adolescents' sCort-reactivity to induced stress. We observed potentially meaningful effects on self-reported mental health for both physical activity conditions, which could be confirmed in a future powered trial., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)