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Introduction: Despite the known health and educational benefits of physical activity and the risks of prolonged sedentary behaviour, only one in 10 adolescents globally meet physical activity guidelines, and three-quarters of the school day is spent sitting. TransformUs , an effective and cost-effective whole-of-school programme for promoting primary school children's physical activity and reducing sedentary behaviour, has been adapted for secondary schools ( TransformUs Secondary ). The aim of this paper is to describe the protocol for TransformUs Secondary in relation to implementation and scale-up across Australia, and the real-world effectiveness of the intervention on adolescents' physical activity and sedentary time, as well as sitting time, sleep, well-being and class and school engagement., Methods and Analysis: A type II hybrid implementation-effectiveness trial will be conducted using a mixed-methods design. For the implementation trial, TransformUs Secondary will be disseminated via key organisations nationally (eg, state departments of education) and available to all Australian secondary schools (n=1453). Implementation outcomes will be evaluated using the RE-AIM framework (reach, adoption, implementation and maintenance). Data will be collected at the school and teacher levels via the TransformUs website (website analytics), descriptive quantitative surveys, text messages to teachers and qualitative interviews with teachers, students and representatives from key organisations. Descriptive statistics will summarise quantitative data, with regression analyses examining the associations between implementation strategies and outcomes. Implementation levels will be classified as low, moderate or high based on the extent of intervention delivery. Qualitative data will be thematically analysed.We will assess effectiveness outcomes in 10 Victorian secondary schools using a pragmatic 1:1 waitlist control design. The target sample is 600 Year 7-10 students (12-16 years). Primary outcomes include adolescents' physical activity and sedentary time (assessed with accelerometry), and secondary outcomes include health (sleep and well-being), class and school engagement (on-task behaviour assessed via classroom observation and school attendance) and sitting time (assessed with posture monitors). Descriptive analyses will summarise students' demographics, physical activity, sedentary behaviour and engagement, while mixed models will evaluate intervention effects on these outcomes, adjusted for confounders. Additionally, qualitative data will be thematically analysed using deductive and inductive coding in NVivo., Ethics and Dissemination: These trials were approved by the Deakin University Human Research Ethics Committee (2021-269) and by the following education authorities: Australian Capital Territory Education Directorate (RES 2317), New South Wales Department of Education (2022253), Northern Territory Department of Education (20865), Victoria Department of Education (2023_004712), Queensland Department of Education (550/27/2585), South Australian Department of Education (2022-0019), Tasmanian Department of Education (2022-25), Western Australian Department of Education (D23/1152724), and Melbourne Archdiocese Catholic Schools (1232). Results from this study will be disseminated through peer-reviewed journal articles, scientific conferences, summary reports to students and schools and stakeholder meetings., Trial Registration Number: Australian Clinical Trials Registration Registry (ACTRN12622000600741)., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY. Published by BMJ Group.)

Objectives: Growing evidence supports the important role of 24-hour movement behaviours (MB) in preventing childhood obesity. However, research to understand the heterogeneity and variability of MB among individuals and what kind of typologies of individuals are at risk of developing obesity is lacking. To bridge this gap, this study identified typologies of 24-hour MB in children and adolescents and investigated their associations with adiposity indicators., Methods: In this cross-sectional study, 374 children and 317 adolescents from the Czech Republic wore wrist-worn accelerometers for seven consecutive days. Time spent in moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), sedentary behaviour (SB), and sleep was quantified using raw accelerometery data. Adiposity indicators included body mass index (BMI) z-score, fat mass percentage (FM%), fat mass index (FMI), and visceral adipose tissue (VAT). Bias-adjusted latent profile analysis was used on the 24-hour MB data to identify MB typologies and their associations with adiposity indicators. The models were adjusted for potential confounders. The identified typologies were labelled to reflect the behavioural profiles of bees to aid interpretability for the general public., Results: Two typologies were identified in children: highly active Workers characterised by high levels of MVPA and LPA, and inactive Queens characterised by low levels of MVPA and LPA, high levels of SB and longer sleep duration compared to Workers. In adolescents, an additional typology labelled as Drones was characterised by median levels of MVPA, LPA, SB and longest sleep duration. After controlling for covariates, we found that children labelled as Queens were associated with 1.38 times higher FM%, 1.43 times higher FMI, and 1.67 times higher VAT than Workers. In adolescents, Drones had 1.14 times higher FM% and Queens had 1.36 higher VAT in comparison with Workers, respectively., Conclusion: Our study highlights the importance of promoting active lifestyles in children and adolescents to potentially reduce adiposity. These findings can provide insights for interventions aimed at promoting healthy MB and preventing childhood obesity., (© 2024. The Author(s).)

Purpose: This quasi-experimental study examined the impact of height-adjustable desks in combination with prompts to break up prolonged sitting time during class time and identified social and motivational factors associated with breaking up sitting time among adolescents. Teachers' perceptions of strategies were also examined., Methods: Over 17 weeks, 1 classroom in a government secondary school in Melbourne, Australia, was equipped with 27 height-adjustable desks and prompts (posters and desk stickers) to break up classroom sitting time. Teachers received professional development in the use of the desks and prompts. One group of adolescents (n = 55) had 2-5 lessons/week using the height-adjustable desks in an intervention classroom, and a comparison group matched by year level and subject (n = 50) was taught in traditional "seated" classrooms. Adolescents wore an activPAL monitor at baseline (T0), 4 weeks (T1), and 17 weeks (T2) and completed a survey at T0 and T2. Six teachers participated in interviews at T2. Effect sizes were calculated (d)., Results: Linear mixed models found that, compared to the traditional "seated" classrooms, the adolescents in the intervention classroom had significantly lower sitting time (T1: -9.7 min/lesson, d = -0.96; T2: -6.7 min/lesson, d = -0.70) and time spent in sitting bouts >15 min (T2: -11.2 min/lesson, d = -0.62), and had significantly higher standing time (T1: 7.3 min/lesson, d = 0.84; T2: 5.8 min/lesson, d = 0.91), number of breaks from sitting (T1: 1.3 breaks/lesson, d = 0.49; T2: 1.8 breaks/lesson, d = 0.67), and stepping time (T1: 2.5 min/lesson, d = 0.66). Intervention classroom adolescents reported greater habit strength (d = 0.58), self-efficacy for breaking up sitting time (d = 0.75), and indicated that having a teacher/classmate remind them to stand as helpful (d = 0.50)., Conclusion: This intervention shows promise for targeting sitting behaviors in the classroom and indicates that incorporating social and motivational strategies may further enhance outcomes., (Copyright © 2020. Production and hosting by Elsevier B.V.)

Background: While the relationship between sedentary time and adiposity markers may be independent of moderate-to-vigorous intensity physical activity (MVPA) among adolescents, little is known about the role of light-intensity physical activity (LIPA) in this relationship. The aim of this cross-sectional study was to examine whether device-measured LIPA and MVPA moderate the associations between objectively measured sitting time and adiposity markers (body mass index (BMI)) and waist circumference (WC)) among adolescents., Methods: This study included accelerometer and inclinometer data obtained from 219 adolescents (age = 14.9 ± 1.6 years, mean ± SD), collected during 2014 and 2015 in Melbourne, Australia. ActiGraph GT3X accelerometers were used to determine time spent in total-LIPA (101 counts/min to 3.99 metabolic equivalents (METs)) was dichotomized into low-LIPA (101-799 counts/min) and high LIPA (800 counts/min to 3.99 METs), and MVPA (≥ 4 METs). The average time spent sitting was obtained from activPAL inclinometers. Anthropometric measures were assessed by trained staff. Interactions between sitting and total-LIPA, low-LIPA, high-LIPA, and MVPA on BMI z-score (zBMI) and WC z-score (zWC), respectively, were examined using linear regression, adjusting for age and sex; and moderation by total-LIPA, low-LIPA, high-LIPA, and MVPA were examined by adding interaction terms. Significant interaction effects were probed by comparing associations at the mean and at 1 SD below and above the mean., Results: Total-LIPA significantly moderated the association between sitting time and zBMI, and low-LIPA significantly moderated the association between sitting time and zBMI and zWC. No other associations were found for total-LIPA, high-LIPA, or MVPA. Specifically, at high levels of total-LIPA (+1 SD), there is a negative association between sitting time and zBMI. In addition, at high levels of low-LIPA (+1 SD), there is a negative association between sitting time and zBMI and zWC., Conclusion: Associations between sitting and adiposity depended on time spent in total-LIPA and low-LIPA, but not high-LIPA or MVPA. Results suggest that increasing time spent in LIPA may provide protection from the deleterious effects of sitting on adiposity markers among adolescents. Experimental evidence is needed to support these conclusions., (Copyright © 2020. Production and hosting by Elsevier B.V.)

Background: Globally, many children fail to meet the World Health Organization's physical activity and sedentary behaviour guidelines. Schools are an ideal setting to intervene, yet despite many interventions in this setting, success when delivered under real-world conditions or at scale is limited. This systematic review aims to i) identify which implementation models are used in school-based physical activity effectiveness, dissemination, and/or implementation trials, and ii) identify factors associated with the adoption, implementation and sustainability of school-based physical activity interventions in real-world settings., Methods: The review followed PRISMA guidelines and included a systematic search of seven databases from January 1st, 2000 to July 31st, 2018: MEDLINE, EMBASE, CINAHL, SPORTDiscus, PsycINFO, CENTRAL, and ERIC. A forward citation search of included studies using Google Scholar was performed on the 21st of January 2019 including articles published until the end of 2018. Study inclusion criteria: (i) a primary outcome to increase physical activity and/or decrease sedentary behaviour among school-aged children and/or adolescents; (ii) intervention delivery within school settings, (iii) use of implementation models to plan or interpret study results; and (iv) interventions delivered under real-world conditions., Exclusion Criteria: (i) efficacy trials; (ii) studies applying or testing school-based physical activity policies, and; (iii) studies targeting special schools or pre-school and/or kindergarten aged children., Results: 27 papers comprising 17 unique interventions were included. Fourteen implementation models (e.g., RE-AIM, Rogers' Diffusion of Innovations, Precede Proceed model), were applied across 27 papers. Implementation models were mostly used to interpret results (n = 9), for planning evaluation and interpreting results (n = 8), for planning evaluation (n = 6), for intervention design (n = 4), or for a combination of designing the intervention and interpreting results (n = 3). We identified 269 factors related to barriers (n = 93) and facilitators (n = 176) for the adoption (n = 7 studies), implementation (n = 14 studies) and sustainability (n = 7 studies) of interventions., Conclusions: Implementation model use was predominately centered on the interpretation of results and analyses, with few examples of use across all study phases as a planning tool and to understand results. This lack of implementation models applied may explain the limited success of interventions when delivered under real-world conditions or at scale., Trial Registration: PROSPERO (CRD42018099836).

Background: This study describes patterns of adolescents' objectively-measured sitting volume, sitting bouts, and breaks in sitting during different days and periods of the day, and explored differences by sex and weekdays versus weekend days., Methods: ActivPAL™ data were collected in August 2014-December 2015 from adolescents attending secondary government schools in Melbourne Australia. Eight periods (early morning, mid-morning, morning break, late morning, lunch, early afternoon, late-afternoon and evening) were extracted for each day. School time, class time and out-of-school time were also extracted for weekdays. The percentage of time sitting, percentage of each hour in prolonged sitting (sitting bout ≥10 min), and number of sitting breaks/hour were calculated for each period. Differences by sex, and week and weekend days were determined using t-tests., Results: Participants (n = 297, 15.4 ± 1.6 years) spent 68% of their day sitting; ~ 30% of each hour in prolonged sitting and 3.1 sitting breaks/hour. Sitting time was greater during class time (75%) and school (70%) compared to out-of-school time (65%). Sitting patterns differed between week and weekend days for all periods except the evening period. Girls had higher proportion of sitting during class than boys (76% vs 72% respectively) and school hours (72% vs 67%), more prolonged sitting during school hours (27% vs 23%), and more sitting breaks per hour during out-of-school time (2.6 vs 2.4), but fewer during class (2.5 vs 3.3) and school hours (2.7 vs 3.3). Sitting patterns did not differ by sex on weekend days., Conclusions: Adolescents spent two-thirds of their waking hours sitting, with distinct patterns on weekdays and weekend days. Even though boys and girls were exposed to the same school day routine, girls spent more time sitting and had fewer sitting breaks. Class times, school breaks and the evening period were identified as key intervention periods. Further research is needed to understand the behavioural differences, and guide future intervention design.