Background:The tracking of clustered cardiometabolic risk from childhood to young adulthood, i.e., whether an unfavourable cardiometabolic risk profile persists from childhood into young adulthood, remain uncertain and has previously not included factors like sedentary time and cardiorespiratory fitness. Methods:We used longitudinal data from the Physical Activity among Norwegian Children Studies (PANCS), where 731 participants participated at age 9 (2005-2006) and 258 of these again at age 24 (2019-2021). Multiple imputation was performed for all eligible participants at age 24 (n = 708). The cardiometabolic risk factors comprised body mass index (BMI), waist circumference, device-measured sedentary time, directly measured peak oxygen uptake (VO2peak), systolic blood pressure, LDL-cholesterol, insulin, high-sensitivity CRP, and a clustered risk Z-score. Tracking was analysed using regression models. Results:Waist circumference and BMI demonstrated strong tracking, whereas moderate tracking was observed for VO2peak, LDL-cholesterol, systolic blood pressure, and clustered cardiometabolic risk. Insulin, high-sensitivity CRP, and sedentary time exhibited no tracking. Unfavourable childhood levels of risk factors demonstrating moderate to strong tracking were highly predictive, with those in the least favourable quartile of clustered risk at age 9 almost six times more likely than their peers to be in the least favourable quartile at age 24 years. Tracking was generally similar between sexes, but waist circumference tracked somewhat stronger among females while VO2peak tracked stronger among males. Conclusions:Several cardiometabolic risk factors demonstrated moderate to strong tracking from childhood to young adulthood, supporting early intervention. However, sedentary behaviour may be less stable and easier to modify compared with more stable cardiometabolic risk factors.

BACKGROUND:Many young people fail to achieve the minimum recommended amount of physical activity to benefit their health. Understanding the nature of age-related changes in behaviour and how this varies for population sub-groups is informative for intervention design. The aim of this study was to describe age-related changes in physical activity and sedentary time and examine variability in patterns of change across demographic sub-groups. METHODS:Data are from 13 studies in the International Children's Accelerometry Database (ICAD), all of which provided ≥2 waves of waist-worn accelerometer data. Annual change in sedentary time, light intensity physical activity (LPA) and moderate to vigorous intensity physical activity (MVPA) were estimated using three level mixed effects linear regression models, using participant age as the exposure variable. In interaction models, we examined whether changes in behaviour differed by day of the week (weekday/ weekend), age at baseline assessment (<10/ ≥ 10 years), sex, weight category, maternal education and ethnicity. RESULTS:In total, 6567 participants provided two or more waves of valid accelerometer data (44.5% boys, mean (SD) baseline age 10.6 (2.1) years (range 4.1-15.8 years)). Across the week and for all studied sub-groups, sedentary time increased by approximately 25 minutes/day/year of age, LPA decreased by approximately 22 minutes/day/year of age and MVPA decreased by approximately 3 minutes/day/year of age. The annual increase in sedentary time was greater in girls compared to boys (β (95% confidence interval) change (min) for each additional year of age: girls, 25.9 (25.4, 26.4); boys, 23.6 (23.0, 24.2)) and in adolescents compared to children (adolescents, 27.0 (26.5, 27.6); children, (23.5 (22.9, 24.2)). The annual decrease in MVPA was greater in boys compared to girls (boys, -2.7 (-3.0, -2.5); girls, -2.2 (-2.4, -2.0)) and at the weekend compared to during the week (weekend, -3.0 (-3.3, -2.8); weekday -2.3 (-2.5, -2.1)). CONCLUSION:Accelerometer assessed sedentary time increased whilst LPA and MVPA decreased during childhood and adolescence. This overall pattern was observed across the week and in all studied sub-groups, but small differences in the magnitude of changes can be used to guide the timing and targeting of behaviour change interventions, such as designing physical activity interventions which focus on weekends where a child's time is less structured.

Objective:To examine the mediation of obesity-related variables in the association between physical fitness and cardiometabolic risk in children and adolescents. Design:Systematic review and meta-analysis. Data sources:Studies from electronic databases from inception to 31 December 2023. Eligibility criteria for selecting studies:Included were 123 observational studies (cross-sectional and longitudinal) that assessed risk by constructing a continuous score incorporating cardiometabolic parameters. Studies were considered if they evaluated at least one fitness component as an exposure in children and adolescents (5-19 years). Thirty-one were included in the main meta-analyses. Results:Cross-sectional findings indicate that cardiorespiratory fitness is modestly but beneficially associated with cardiometabolic risk, either indirectly via obesity-related variables (indirect standardized beta coefficient [βIndirect]=-0.17; 95% confidence interval [CI] -0.23; -0.11; inconsistency index [I2]=94.4%) or directly and independently from obesity-related variables (r=-0.11; 95% CI -0.15; -0.07; I2=87.4%), whereas muscular fitness seems to be associated with risk only via obesity-related variables (βIndirect=-0.34; 95% CI -0.47; -0.20; I2=85.1%). There was no cross-sectional difference between biological sexes (p≥0.199). Longitudinal findings indicate no total (r=-0.12; 95% CI -0.24; 0.01; I2=23.1%) and direct (r=-0.03; 95% CI -0.08; 0.03; I2=0%) associations. Conclusion:The association between fitness and risk appears to take place either indirectly through the reduction of obesity-related levels or directly by influencing risk. The latter underscores that the inverse association extends beyond a mere reduction in obesity-related variables, encompassing specific enhancements linked to exercise training, including increased metabolic efficiency, and cardiovascular capacity. PROSPERO registration number:CRD42022354628.

PURPOSE:To explore the multivariate pattern associations between physical fitness and adiposity with cardiometabolic risk among children and adolescents. METHOD:Cross-sectional study including 6405 participants (6-18 y; 3567 females). Waist circumference, sum of 3 skinfolds, and physical fitness measures (abdominal endurance, agility, cardiorespiratory fitness, flexibility, speed, and lower/upper limb power) were assessed. A continuous risk score (cMetS) was calculated as the mean of the z-scores for glucose, systolic blood pressure, total cholesterol and high-density lipoprotein cholesterol ratio, and triglycerides. Three models were tested using multivariate patterns analysis, of which the following explanatory variables were included: (1) both physical fitness and adiposity measures, (2) only physical fitness, and (3) physical fitness adjusted for adiposity measures. In the latter model, cMetS was also adjusted for adiposity. RESULTS:Inverse associations with cMetS were found for abdominal endurance, agility, cardiorespiratory fitness, lower limb power, and speed among males; and agility and cardiorespiratory fitness among females; without adjustment for adiposity. When cMetS and physical fitness were adjusted for adiposity, agility (only among males) and cardiorespiratory fitness remained associated with cMetS. CONCLUSION:The findings highlight the consistent adiposity-independent role of cardiorespiratory fitness as the primary fitness marker associated with cardiometabolic health during childhood and adolescence, alongside evidence linking agility to risk.

ABSTRACT:de Castro Silveira, JF, Reuter, CP, Aadland, E, Andersen, LB, Nevill, AM, Mello, JB, and Gaya, AR. Normalizing and standardizing physical fitness by sex, age, and body size in Brazilian children and adolescents: A PROESP-BR study. J Strength Cond Res 39(4): e598-e609, 2025-The study aimed to use allometric modeling to identify how body size dimensions should be exponentiated to normalize physical fitness variables. It also aimed to provide reference values to standardize physical fitness into z-scores by sex, age, and body size dimensions. Cross-sectional data from 95,691 Brazilian children and adolescents (52,747 males; 55.1%; aged 6-18 years) were analyzed, including physical fitness tests (abdominal endurance, agility, cardiorespiratory fitness, flexibility, lower and upper limbs power, and speed) and anthropometric measures (arm span, body mass, and height). Allometric modeling was applied, and statistical significance was determined using p values less than 0.05. Results revealed that taller individuals with longer levers generally performed better in physical fitness tests (p ≤ 0.007), regardless of biologic sex and chronologic age, except for flexibility tests where shorter individuals with longer upper limbs performed better (p ≤ 0.001). The impact of greater body mass varied depending on whether the test required the individual to carry his/her own weight. Among females, performance in weight-bearing/carrying tests peaked at middle adolescence and declined thereafter, while among males, performance steadily increased with age. In conclusion, the present study provided reference equations to calculate z-scores independent from biologic sex and chronologic age and dimensionless to body size variables, and also suggested how arm span, body mass, and height could be exponentiated for use in the denominator of a physical fitness scaled ratio or index.

Background:There is insufficient evidence to provide recommendations for leisure-time physical activity among workers across various occupa-tional physical activity levels.This study aimed to assess the association of leisure-time physical activity with cardiovascular and all-cause mortality across occupational physical activity levels. Methods:This study utilized individual participant data from 21 cohort studies,comprising both published and unpublished data.Eligibility criteria included individual-level data on leisure-time and occupational physical activity(categorized as sedentary,low,moderate,and high)along with data on all-cause and/or cardiovascular mortality.A 2-stage individual participant data meta-analysis was conducted,with separate analysis of each study using Cox proportional hazards models(Stage 1).These results were combined using random-effects models(Stage 2). Results:Higher leisure-time physical activity levels were associated with lower all-cause and cardiovascular mortality risk across most occupa-tional physical activity levels,for both males and females.Among males with sedentary work,high compared to sedentary leisure-time physical activity was associated with lower all-cause(hazard ratios(HR)=0.77,95％confidence interval(95％CI):0.70-0.85)and cardiovascular mortality(HR=0.76,95％CI:0.66-0.87)risk.Among males with high levels of occupational physical activity,high compared to sedentary leisure-time physical activity was associated with lower all-cause(HR=0.84,95％CI:0.74-0.97)and cardiovascular mortality(HR=0.79,95％CI:0.60-1.04)risk,while HRs for low and moderate levels of leisure-time physical activity ranged between 0.87 and 0.97 and were not statistically significant.Among females,most effects were similar but more imprecise,especially in the higher occupational physical activity levels. Conclusion:Higher levels of leisure-time physical activity were generally associated with lower mortality risks.However,results for workers with moderate and high occupational physical activity levels,especially women,were more imprecise.Our findings suggests that workers may benefit from engaging in high levels of leisure-time physical activity,irrespective of their level of occupational physical activity.

Purpose The primary aims of this study were to examine the effects of 9 weeks of aerobic training, comprising three 30-min sessions per week, on VO2max, inhibitory control, and plasma brain-derived neurotrophic factor (BDNF) levels among adolescents aged 16-19 years. Methods One hundred twenty-one untrained or recreationally active adolescents from a Danish high school were enrolled in the study, with 58 females (17.8 +/- 0.8 years) and 27 males (18.0 +/- 0.9 years) completing it. Participants were randomly divided into three groups performing aerobic training at either moderate-intensity (MIT: 60%-70% heart rate reserve [HRR]) or high-intensity (HIT: 80%-100% HRR) or a passive control group (CON) continuing their habitual lifestyle. Both the training groups exercised for 3x30 min per week for 9 weeks using a combination of cycling and running. Before and after the intervention period maximal oxygen uptake (VO2max) and the primary outcomes (inhibitory control measured by a modified flanker task, and resting plasma levels of BDNF) were evaluated. Results After the intervention period, the HIT group demonstrated a larger increase in VO2max compared to both the CON and MIT groups, while no significant effects were observed on inhibitory control or plasma BDNF levels in any training group. However, compared to the CON group, the HIT group exhibited a tendency for greater improvement in the flanker interference score (accuracy), attributable to enhanced accuracy on the incongruent stimuli from pre to post. Conclusion Aerobic training in adolescents increased cardiorespiratory fitness in an intensity-dependent manner, but no clear effects were observed on neither inhibitory control nor resting plasma BDNF levels. Clinical Trial Registration: NCT02075944.

PURPOSE:The relationship between sedentary time, physical activity, and cardiometabolic risk factors during the transition from adolescence to adulthood remains uncertain. We examined the prospective associations of sedentary time and physical activity at age 15 yr with cardiometabolic risk markers at age 24 yr. METHODS:We used data from the Physical Activity among Norwegian Children Studies. Sedentary time, moderate-to-vigorous physical activity (MVPA), and vigorous physical activity (VPA) were measured by accelerometry. Outcomes included body mass index (BMI), waist circumference, visceral fat, maximal oxygen uptake (V̇O 2max ), systolic blood pressure, LDL-cholesterol, insulin, high-sensitivity C-reactive protein, and a clustered risk Z -score. The prospective associations were modeled through regression. RESULTS:A total of 731 boys and girls participated at ages 9 yr (2005-2006) and 15 yr (2011-2012), and 258 of these participated again at age 24 yr (2019-2021). Multiple imputation was performed for all eligible individuals ( n = 708). Each standard deviation increase (minutes per day) in sedentary time at age 15 yr was associated with lower V̇O 2max at age 24 yr ( β = -1.6 mL·kg -1 ·min -1 ; 95% confidence interval (CI), -2.8 to -0.5). Each standard deviation increase (minutes per day) in MVPA ( β = 1.6 mL·kg -1 ·min -1 ; 95% CI, 0.8 to 2.4) and VPA ( β = 1.6 mL·kg -1 ·min -1 ; 95% CI, 0.8 to 2.4) at age 15 yr were associated with higher V̇O 2max at age 24 yr. VPA in adolescence was further inversely associated with visceral fat mass ( β = -41 g; 95% CI, -78 to -3), insulin level ( β = -4.3 pmol·L -1 ; 95% CI, -8.2 to -0.4), and the clustered risk Z -score ( β = -0.09; 95% CI, -0.18 to -0.01) in young adulthood. Childhood BMI modified the association of both MVPA and VPA with clustered risk, with the greatest magnitude of association observed in the highest BMI tertile. CONCLUSIONS:Physical activity, especially of vigorous intensity, during adolescence appears to beneficially affect cardiometabolic health in young adulthood. These health benefits may be most pronounced among overweight/obese youth.

This article presents a scoping review of the existing research on the use of digital data in social work. This review focuses on research that includes empirical investigations of digital data on citizens in social work practices. The purpose of this review is to map the emerging field of research and contribute knowledge of the role of digital data on citizens in social work. This review includes twenty-eight articles published between 2013 and 2020, and concludes that data pervade almost every aspect of social work and that there is a variety of research on the use of data in social work. However, detailed analyses of data that describe and conceptualise the production, circulation and utilisation of data are few. In consequence, this article introduces and discusses concepts from other data-laden fields of research, and calls for further research that addresses the challenges presented by digital data used in social work.

Introduction This systematic review with meta-analysis investigates the effect of glucocorticoids on maximal and submaximal performance in healthy subjects. Methods We searched for randomised controlled trials investigating the effect of glucocorticoids on physical performance in Web of Science, Scopus, Medline, Embase and SportDiscus in March 2021. Risk of bias was assessed with the revised Cochrane Collaboration Risk of Bias Tool (RoB2). Data from random effect models are presented as standardized difference in mean (SDM) with 95% confidence interval. We included 15 studies comprising 175 subjects. Results Two studies had high risk of bias. Glucocorticoids had a small positive effect on maximal physical performance compared to placebo (SDM 0.300, 95% CI 0.080 to 0.520) and the SDM for the 13 included comparisons was not heterogeneous ( I 2 = 35%, p = 0.099). Meta regression found no difference in the effect of acute treatment vs. prolonged treatment or oral ingestion vs. inhalation ( p > 0.124). In stratified analysis prolonged treatment (SDM 0.428, 95% CI 0.148 to 0.709) and oral ingestion (SDM 0.361, 95% CI 0.124 to 0.598) improved physical performance. Glucocorticoids improved aerobic performance (SDM 0.371, 95% CI 0.173 to 0.569) but not anaerobic performance ( p = 0.135). Glucocorticoids did not change energy expenditure during submaximal performance (SDM 0.0.225 95% CI −0.771 to 0.112). Discussion This study indicates that glucocorticoids improves maximal performance and aerobic performance. Glucocorticoids did not affect the energy expenditure during submaximal performance. The conclusions are based on relatively few subjects leading to limited statistical power and uncertain estimates. Still, these results are consistent and should be of interest to WADA and anyone concerned about fair play. Systematic Review Registration Open Science Framework 2021-04-29 ( https://osf.io/fc29t/ ).

The measurement of physical fitness has a history that dates back nearly 200 years. Recently, there has been an increase in international research and surveillance on physical fitness creating a need for setting international priorities that could help guide future efforts. This study aimed to produce a list of the top 10 international priorities for research and surveillance on physical fitness among children and adolescents. Using a twin-panel Delphi method, two independent panels consisting of 46 international experts were identified (panel 1 = 28, panel 2 = 18). The panel participants were asked to list up to five priorities for research or surveillance (round 1), and then rated the items from their own panel on a 5-point Likert scale of importance (round 2). In round 3, experts were asked to rate the priorities identified by the other panel. There was strong between-panel agreement (panel 1: rs = 0.76, p < 0.01; panel 2: rs = 0.77, p < 0.01) in the priorities identified. The list of the final top 10 priorities included (i) “conduct longitudinal studies to assess changes in fitness and associations with health”. This was followed by (ii) “use fitness surveillance to inform decision making”, and (iii) “implement regular and consistent international/national fitness surveys using common measures”. The priorities identified in this study provide guidance for future international collaborations and research efforts on the physical fitness of children and adolescents over the next decade and beyond.

The objective of the present study is to review and meta-analyze the effect of E-cycling on health outcomes. We included longitudinal experimental and cohort studies investigating the effect of E-cycling on health outcomes. The studies were identified from the seven electronic databases: Web of Science, Scopus, Medline, Embase, PsycINFO, Cinahl and SportDiscus and risk of bias was assessed with the revised Cochrane Collaboration Risk of Bias Tool (RoB2). We performed meta-analysis with random effects models on outcomes presented in more than one study. Our study includes one randomized controlled trial, five quasi experimental trials and two longitudinal cohort studies. The trials included 214 subjects of whom 77 were included in control groups, and the cohort studies included 10,222 respondents at baseline. Maximal oxygen consumption and maximal power output were assessed in four and tree trials including 78 and 57 subjects, respectively. E-cycling increased maximal oxygen consumption and maximal power output with 0.48 SMD (95%CI 0.16–0.80) and 0.62 SMD (95%CI 0.24–0.99). One trial reported a decrease in 2-h post plasma glucoses from 5.53 ± 1.18 to 5.03 ± 0.91 mmol L−1 and one cohort study reported that obese respondents performed 0.21 times more trips on E-bike than respondents with normal weight. All the included studies had a high risk of bias due to flaws in randomization. However, the outcomes investigated in most studies showed that E-cycling can improve health.

The present study aims to verify the odds of remaining with the clustering of 3 or more, 4 or more, and 5 or more risk factors across a 2-year time span. Observational longitudinal study that included 358 children and adolescents (10.96 ± 2.28 years of age at baseline). Cardiorespiratory fitness, glucose, systolic blood pressure, total cholesterol/high-density lipoprotein cholesterol ratio, triglycerides, and waist circumference were assessed. The number of children in whom the risk factors were not independently distributed was analyzed. Odds ratios of presenting n risk factors clustered at follow-up according to the number of risk factors observed at baseline were calculated. More participants than expected were found presenting clustering of 4 or more and 5 or more risk factors at both baseline (11.7

ABSTRACT Introduction The United Kingdom and World Health Organization recently changed their youth physical activity (PA) guidelines from 60 min of moderate- to vigorous-intensity PA (MVPA) every day, to an average of 60 min of MVPA per day, over a week. The changes are based on expert opinion due to insufficient evidence comparing health outcomes associated with different guideline definitions. This study used the International Children’s Accelerometry Database to compare approaches to calculating youth PA compliance and associations with health indicators. Methods Cross-sectional accelerometer data (n = 21,612, 5–18 yr) were used to examine compliance with four guideline definitions: daily method (DM; ≥60 min MVPA every day), average method (AM; average of ≥60 min MVPA per day), AM5 (AM compliance and ≥5 min of vigorous PA [VPA] on ≥3 d), and AM15 (AM compliance and ≥15 min VPA on ≥3 d). Associations between compliance and health indicators were examined for all definitions. Results Compliance varied from 5.3% (DM) to 29.9% (AM). Associations between compliance and health indicators were similar for AM, AM5, and AM15. For example, compliance with AM, AM5, and AM15 was associated with a lower BMI z-score (statistics are coefficient [95% CI]): AM (−0.28 [−0.33 to −0.23]), AM5 (−0.28 [−0.33 to −0.23], and AM15 (−0.30 [−0.35 to −0.25]). Associations between compliance and health indicators for DM were similar/weaker, possibly reflecting fewer DM-compliant participants with health data and lower variability in exposure/outcome data. Conclusions Youth completing 60 min of MVPA every day do not experience superior health benefits to youth completing an average of 60 min of MVPA per day. Guidelines should encourage youth to achieve an average of 60 min of MVPA per day. Different guideline definitions affect inactivity prevalence estimates; this must be considered when analyzing data and comparing studies.

Objectives. We aimed to examine the effect of beta2-agonists on anaerobic performance in healthy non-asthmatic subjects. Design. Systematic review and meta-analysis. Eligibility criteria. We searched four databases (PubMed, Embase, SPORTDiscus and Web of Science) for randomized controlled trials, published until October 2018, examining the effect of beta2agonists on maximal physical performance lasting one minute or shorter. Data are presented as standardized difference in mean (SDM) with 95% confidence intervals. Results. Thirty-two studies were included in the present meta-analysis. The studies include 41 different randomized and placebo controlled comparisons with beta2-agonists comprising 317 participants in crossover trials, and 110 participants in parallel trials. Beta2-agonists improved anaerobic performance by 5 % (SMD 0.27, 0.14-0.41) and the effect was related to treatment duration. In a stratified analysis the SDM was 0.18 (0.05-0.30) for acute treatment and 0.53 (0.190.88) for treatment for multiple weeks. Analyses stratified for the type of performance showed that strength 0.33 (0.12-0.53) and sprint 0.18 (0.050.30) performance was improved by beta2-agonists. Conclusion/implication. Our study shows that non-asthmatic subjects can improve sprint and strength performance by using beta2-agonists. Multiple weeks of treatment is more effective for

Abstract Purpose The Structured Days Hypothesis (SDH) posits that children’s behaviors associated with obesity – such as physical activity – are more favorable on days that contain more ‘structure’ (i.e., a pre-planned, segmented, and adult-supervised environment) such as school weekdays, compared to days with less structure, such as weekend days. The purpose of this study was to compare children’s moderate-to-vigorous physical activity (MVPA) levels on weekdays versus weekend days using a large, multi-country, accelerometer-measured physical activity dataset. Methods Data were received from the International Children’s Accelerometer Database (ICAD) July 2019. The ICAD inclusion criteria for a valid day of wear, only non-intervention data (e.g., baseline intervention data), children with at least 1 weekday and 1 weekend day, and ICAD studies with data collected exclusively during school months, were included for analyses. Mixed effects models accounting for the nested nature of the data (i.e., days within children) assessed MVPA minutes per day (min/day MVPA) differences between weekdays and weekend days by region/country, adjusted for age, sex, and total wear time. Separate meta-analytical models explored differences by age and country/region for sex and child weight-status. Results/findings Valid data from 15 studies representing 5794 children (61% female, 10.7 ± 2.1 yrs., 24% with overweight/obesity) and 35,263 days of valid accelerometer data from 5 distinct countries/regions were used. Boys and girls accumulated 12.6 min/day (95% CI: 9.0, 16.2) and 9.4 min/day (95% CI: 7.2, 11.6) more MVPA on weekdays versus weekend days, respectively. Children from mainland Europe had the largest differences (17.1 min/day more MVPA on weekdays versus weekend days, 95% CI: 15.3, 19.0) compared to the other countries/regions. Children who were classified as overweight/obese or normal weight/underweight accumulated 9.5 min/day (95% CI: 6.9, 12.2) and 10.9 min/day (95% CI: 8.3, 13.5) of additional MVPA on weekdays versus weekend days, respectively. Conclusions Children from multiple countries/regions accumulated significantly more MVPA on weekdays versus weekend days during school months. This finding aligns with the SDH and warrants future intervention studies to prioritize less-structured days, such as weekend days, and to consider providing opportunities for all children to access additional opportunities to be active.

Our aim was to assess the association between changes in active travel to school and changes in different intensities of physical activity (i.e. moderate - MPA and vigorous - VPA) and time spent sedentary (SED) among adolescents and assess the moderating effect of children's sex, age and weight status. Data from six cohort studies in the International Children's Accelerometry Database were used (4108 adolescents aged 10-13y at baseline, with 1.9±0.7y of follow-up). Participants self-reported travel mode to school at baseline and follow-up. Mutually exclusive categories of change were created using passive (e.g. by car) or active (cycling or walking) forms of transport (active/active, passive/active, active/passive, passive/passive). Multilevel linear regression analyses assessed associations with change in accelerometer-assessed time spent MPA, VPA and SED, adjusting for potential confounders. The moderation of sex, age and weight status was tested though the inclusion of interaction terms in the regression models. Relative to those remaining in active travel (active/active), participants classified as passive/active increased VPA (B: 2.23 min/d; 95%CI: 0.97-3.48), while active/passive (MPA: -5.38min/d; -6.77 to -3.98; VPA: -2.92min/d; -4.06 to -1.78) and passive/passive (MPA: -4.53min/d; -5.55 to -3.50; VPA: -2.84min/d; -3.68 to -2.01) decreased MPA and VPA. There were no associations with SED. An interaction was observed, age group moderated the association with change in VPA: among 12-13y-olds a greater increase in VPA was observed for the passive/active group compared to active/active. Promoting active travel to school can be a strategy to attenuate the decline in physical activity through adolescence.

Background There is a scarcity of device measured data on temporal changes in physical activity (PA) in large population-based samples. The purpose of this study is to describe gender and age-group specific temporal trends in device measured PA between 2005, 2011 and 2018 by comparing three nationally representative samples of children and adolescents. Methods Norwegian children and adolescents (6, 9 and 15-year-olds) were invited to participate in 2005 (only 9- and 15-year-olds), 2011 and 2018 through cluster sampling (schools primary sampling units). A combined sample of 9500 individuals participated. Physical activity was assessed by hip worn accelerometers, with PA indices including overall PA (counts per minute), moderate-to-vigorous intensity PA (MVPA), and PA guideline adherence (achieving on average ≥ 60 min/day of moderate-to-vigorous PA). Random-effects linear regressions and logistic regressions adjusted for school-level clusters were used to analyse temporal trends. Findings In total, 8186 of the participating children and adolescents provided valid PA data. Proportions of sufficiently active 6-year-olds were almost identical in 2011 and 2018; boys 95% (95% CI: 92, 97) and 94% (95%CI: 92, 96) and girls 86% (95% CI: 83, 90) and 86% (95% CI: 82, 90). Proportions of sufficiently active 15-year-olds in 2005 and 2018 were 52% (95% CI: 46, 59) and 55% (95% CI: 48, 62) in boys, and 48% (95% CI: 42, 55) and 44% (95% CI: 37, 51) in girls, respectively, resulting from small differences in min/day of MVPA. Among 9-year-old boys and girls, proportions of sufficiently active declined between 2005 and 2018, from 90% (95% CI: 87, 93) to 84% (95% CI: 80, 87)) and 74% (95% CI: 69, 79) to 68% (95% CI: 64, 72), respectively. This resulted from 9.7 min/day less MVPA in boys (95% CI: − 14.8, − 4.7; p < 0.001) and 3.2 min/day less MVPA (95% CI: − 7.0, 0.7; p = 0.106) in girls. Conclusions PA levels have been fairly stable between 2005, 2011 and 2018 in Norwegian youth. However, the declining PA level among 9-year-old boys and the low proportion of 15-year-olds sufficiently active is concerning. To evaluate the effect of, and plan for new, PA promoting strategies, it is important to ensure more frequent, systematic, device-based monitoring of population-levels of PA.