Background: Studies indicate that health-related components of physical fitness are associated with mental health outcomes. However, research is scarce concerning this relationship in young adolescents in general and nonexistent in Norwegian populations specifically. The aim of the study was to examine whether body composition, muscular strength and cardiorespiratory fitness were associated with self-reported mental health in Norwegian adolescents. Methods: Adolescents from four regions of Norway (n = 1486; mean age = 13.9; girls = 50.6%) participated. Selfreported mental health (psychological difficulties) was measured by completing the Strengths and Difficulties Questionnaire. Cardiorespiratory fitness was assessed with an intermittent running test; muscular strength was assessed by measuring handgrip strength, standing broad jump and sit-ups; and body composition was assessed by calculating body mass index from weight and height. Linear mixed effects models were conducted to assess the associations between the health-related components of physical fitness and psychological difficulties. School clusters were included as random effects and all models were controlled for sex, socioeconomic status and birthplace (domestic or foreign). Results: Body composition was not associated with psychological difficulties. Muscular strength was independently associated with psychological difficulties, but when all independent variables were entered in the fully adjusted model, only cardiorespiratory fitness was associated with psychological difficulties. Conclusions: There was a small but significant inverse association between cardiorespiratory fitness and levels of psychological difficulties in Norwegian adolescents. The results suggest that muscular strength is not associated with psychological difficulties in adolescents, when controlling for cardiorespiratory fitness. Future research should focus on the prospective association between physical fitness components and mental health outcomes in adolescents. Trial registration: The study is registered in ClinicalTrials.gov ID nr: NCT03817047. Retrospectively registered January 25, 2019.

BackgroundStair climbing is a vigorous activity and can lead to several health benefits. Studies seeking to increase stair climbing in various public locations have shown positive effects, while results from similar studies conducted in the workplace are inconclusive. This study examined stair climbing in the workplace, and monitored effects from a single- and a combined intervention. Interventions were inspired by nudging, the libertarian method of influencing behavior.MethodsBy quasi-experimental design, stair- and elevator traffic in two office buildings was monitored preceding-, during- and following interventions with stair leading footprints alone, and combined with stair-riser banners. Chi square tests were applied to determine differences between baseline and the subsequent periods. Web-based questionnaires were distributed after follow-up period.ResultsElevators and stairs were used 45 237 times, of which 89.6% was stair use. Intervention site stair climbing at baseline (79.0%) was significantly reduced with footprints (-5.1%, p < 0.001), and footprints with stair-riser banners (-5.7%, p < 0.001) while baseline stair climbing at the control site (94.2%) remained stable (p > 0.027).ConclusionsStair climbing was significantly reduced during the intervention periods. Use of stair leading footprints alone, or combined with stair-riser banners in an attempt to influence stair climbing may be ineffective, or cause a negative reaction, when applied in a workplace with a pre-existing high amount of stair climbing.

PurposeThis paper evaluates the implementation of a school-based physical activity intervention and discusses how the intervention outcomes can be influenced by the implementation.Design/methodology/approachIn four of the nine lower secondary schools in which the intervention was conducted, the authors examined implementation fidelity, adaptation, quality, responsiveness and dose received. The authors conducted focus group interviews with teachers (n = 8) and students (n = 46) and made observations. Dose delivered was examined quantitatively, with weekly registrations.FindingsResults showed that two out of four schools made few and positive adaptations, implemented the intervention with high fidelity and quality and responded positively. Four main factors were found to influence implementation: frame factors, intervention characteristics, participant characteristics and provider characteristics.Research limitations/implicationsA cross-sectional design was used and may not represent implementation throughout the whole school year.Practical implicationsIn terms of large-scale implementation, the intervention may be generalizable. However, intervention criteria such as adequate facilities and a flexible timetable may be unattainable for some schools. The intervention can be adapted without compromising its purpose, but adaptations should be a result of cooperation between students and teachers.Originality/valueProcess evaluations on this topic are rare. This study adds to a limited knowledge base concerning what factors may influence implementation of school-based physical activity interventions for adolescents.

Background School-based physical activity interventions evaluating the effect on academic performance usually includes children. We aimed to investigate the effect of a nine-month, school-based physical activity intervention titled School in Motion (ScIM) on academic performance in adolescents. Methods Thirty secondary schools in Norway were cluster-randomized into three groups: the Physically active learning (PAL) group (n = 10), the Don’t worry – Be Happy (DWBH) group (n = 10) or control (n = 10). Target dose in both intervention groups was 120 min/week of additional PA during school hours. Parental consent was obtained from 2084 adolescent students (76%). Standardized national tests in reading and numeracy was conducted at baseline and at the end of the intervention. We used linear mixed model to test intervention effects. We found significant intervention effects in numeracy and reading among students in both interventions when compared with controls. Results The mean difference in change in numeracy was 1.7 (95% CI: 0.9 to 2.5; Cohen’s d = 0.12) and 2.0 (95% CI: 1.4 to 2.7; Cohen’s d = 0.23) points in favour of students in the PAL and DWBH intervention, respectively. Similar results were found for reading, where the mean difference in change was 0.9 (95% CI 0.2 to 1.6; Cohen’s d = 0.06) and 1.1 (95% CI 0.3 to 1.9; Cohen’s d = 0.18) points in favour of students in the PAL and DWBH intervention, respectively. When conducting intention to treat analysis with imputed data the estimates were attenuated and some no longer significant. Conclusion The ScIM study demonstrates that two different school-based PA interventions providing approximately 120 min of additional PA weekly over nine months, significantly improved numeracy and reading performance in 14-year old students compared with controls. However, the results should be interpreted with caution as the effect sizes reported were very small or small and the estimates were attenuated when conducting intention to treat analysis. Despite this, our results are still positive and suggest that PA interventions are viable models to increase academic performance among adolescents. Trial registration Retrospectively registered (25/01/2019): NCT03817047.

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