BackgroundIn 2014 the Danish Government introduced a wide-ranging school reform that applies to all public schools in Denmark. The reform involves changes in several aspects of the school structure and content. In a physical activity promotion perspective, a distinctive feature of the school reform is that it has become mandatory to integrate an average of 45 min of daily physical activity in the regular school day. The overarching objective of the PHASAR study is to evaluate the implementation and effect of this ambitious policy-driven physical activity promotion initiative on physical activity and overweight. This paper describes in detail the study protocol.MethodsThe evaluation is divided into a quantitative effect evaluation and a combined quantitative and qualitative process evaluation. A total of 31 schools are enrolled in the PHASAR study including more than 2,000 school-aged children. Objectively measured physical activity data are obtained in the PHASAR study in 2017/18 and compared to repeated cross sectional data collected in four historical school-based studies from 1998 to 2012. Body mass index data from 2012 to 2018 will be collected from The Child Database, which includes repeated cross-sectional assessments on approximately 100,000 children annually. In the absence of a control group, interrupted time-series analysis will be used to evaluate pre- and post-reform physical activity and body mass index levels and trends. A characterization of the school environment for physical activity promotion on a political, environmental, organizational and individual level and school implementation processes will be conducted to evaluate the implementation process. Data will be collected using interviews, surveys, document analyses and observations.DiscussionThe PHASAR study is a rare opportunity to evaluate the effectiveness of a nation-wide policy-driven school-based physical activity promotion initiative. The use of objectively measured pre- and post-reform physical activity and body mass index data combined with a characterization of the school implementation processes for physical activity promotion will provide a comprehensive source to evaluate the school reform. The study findings have the potential to influence national and international policy makers, health professionals and school staff.

Background and objectiveCardiovascular disease and type 2 diabetes pose a global health burden. Therefore, clarifying the pathology of these risk factors is essential. Previous studies have found positive and negative associations between one or more cardiovascular risk factors and brain-derived neurotrophic factor (BDNF) probably due to diverse methodological approaches when analysing peripheral BDNF levels. Moreover, only a few studies have been performed in youth populations. Consequently, the main objective of this study was to examine the association between serum BDNF and a composite z-score consisting of six cardiovascular risk factors. A secondary aim was to examine the associations between serum BDNF and each of the six risk factors.MethodsFour hundred and forty-seven apparently healthy adolescents between 11–17 years of age participated in this cross-sectional study. Cardiorespiratory fitness (CRF), anthropometrics, pubertal status, blood pressure (BP), serum BDNF, high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), blood glucose and insulin were measured. Information about alcohol consumption and socio-economic status was collected via questionnaires. Associations were modelled using linear regression analysis.ResultsSerum BDNF was positively associated with the composite z-score in the total study sample (standardized beta coefficient (std.β) = 0.10, P = 0.037). In males, serum BDNF was positively associated with the composite z-score (Std. β = 0.14, P = 0.034) and HOMA-IR (Std. β = 0.19, P = 0.004), and negatively associated with CRF (Std. β = -0.15, P = 0.026). In females, BDNF was positively associated with TG (Std. β = 0.14, P = 0.030) and negatively associated with waist circumference (WC) (Std. β = -0.16, P = 0.012).ConclusionSerum BDNF was positively associated with a composite z-score of cardiovascular risk factors. This association seems to be mainly driven by the association between TG, HOMA-IR and serum BDNF, and particularly for males. Further longitudinal research is warranted to determine the temporal relationship between BDNF and cardiovascular risk factors.

Background In 2014, the Danish Government introduced a wide-ranging school reform that applied to all public schools in Denmark. A distinctive feature of the reform was that it became mandatory to implement an average of 45 min of daily physical activity within the curriculum. Using the RE-AIM framework as an evaluation tool, the objective of the current study was to evaluate the reach, effectiveness, adoption, implementation, and maintenance of mandatory physical activity within the curriculum at ten Danish schools. Methods A complementary mixed-methods approach using accelerometers, questionnaires, and semi-structured interviews was conducted. A total of 10 schools were invited to participate, including 846 students, 76 teachers, and 10 school managers on various levels. Students were invited to wear an accelerometer for seven consecutive days. Teachers were invited to participate in a questionnaire, and school managers were encouraged to take part in a semi-structured interview. Results Results showed that, on average, 45.2% of the students were active at least 45 min daily within the curriculum. Teacher and school management interest in physical activity, competencies development, and shared decision-making were identified as central factors for adoption of the requirement. Scheduling physical activity within scheduels and collaborations with external parties were found to influence implementation. Finally, internal coordination, motivated school staff, and school management priority were identified as central factors for maintenance. Conclusions This study provides an evaluation on a nationwide physical activity requirement in Danish public schools. When introducing a wide-ranging nation-wide requirement on physical activity within the curriculum, school managers need to prioritize and support the implementation process. Teachers need to be involved in the decision processes in order to ensure motivation and local ownership. The study also highlights the benefits of an internal coordinator as well as development of a shared strategy among schools, municipalities, and other stakeholders in order to succeed with the implementation.

Combining accelerometry from multiple independent activity monitors worn by the same subject have gained widespread interest with the assessment of physical activity behavior. However, a difference in the real time clock accuracy of the activity monitor introduces a substantial temporal misalignment with long duration recordings which is commonly not considered. In this study, a novel method not requiring human interaction is described for the temporal alignment of triaxial acceleration measured with two independent activity monitors and evaluating the performance with the misalignment manually identified. The method was evaluated with free-living recordings using both combined wrist/hip (n = 9) and thigh/hip device (n = 30) wear locations, and descriptive data on initial offset and accumulated day 7 drift in a large-scale population-based study (n = 2513) were calculated. The results from the Bland–Altman analysis show good agreement between the proposed algorithm and the reference suggesting that the described method is valid for reducing the temporal misalignment and thus reduce the measurement error with aggregated data. Applying the algorithm to the n = 2513 samples worn for 7-days suggest a wide and substantial issue with drift over time when each subject wears two independent activity monitors.

Background In 2014, the Danish Government introduced a wide-ranging school reform that applied to all public schools in Denmark. A distinctive feature of the reform was that it became mandatory to implement an average of 45 minutes of daily physical activity within the curriculum. Using the RE-AIM framework as an evaluation tool, the objective of the current study was to evaluate the reach, effectiveness, adoption, implementation, and maintenance of mandatory physical activity within curriculum at ten Danish schools. Methods A complementary mixed methods approach using accelerometers, questionnaires, and semi-structured interviews was conducted. A total of 11 representative school were invited to participate, including 993 students, 131 teachers, and 11 school managers. Students were invited to wear an accelerometer for seven consecutive days. Teachers were invited to participate in a questionnaire and school managers were encouraged to take part in a semi-structured interview. Results A total of 10 schools were included in the analysis, including 846 students, 76 teachers, and 10 school managers. Results showed that, on average, 45.2% of the students were active at least 45 minutes daily within curriculum. Teacher and school management interest in physical activity, competencies development, and shared decision-making were identified as central factors for adoption of the requirement. Scheduling physical activity within timetables and collaborations with external parties were found to influence the implementation dimension. Finally, internal coordination, motivated school staff, and school management priority were identified as centrals factors for maintenance. Conclusions This study provides an evaluation on a national physical activity requirement in Danish public schools. When introcuding a wide-ranging national requirement on physical activity within curriculum, school managers need to prioritize and support the implementation process. Teachers need to be involved in the decision processes, in order to ensure motivation and local ownership. The study also highlight the benefits of an internal coordinator as well as development of a shared strategy among schools, municipalities, and other stakeholders in order to succeed with the implementation.