Impact of a nationwide school policy on body mass index in Danish school children: An interrupted time series analysis.

Objectives: A new school policy mandating 45 min physical activity daily during school was introduced in Denmark in 2014. We aimed to evaluate the effect of this policy on BMI in school-aged children. It was hypothesized that the school policy would decrease BMI, especially in the obese fraction of the population (90th percentile BMI). Study design: This register-based study was conducted as a natural experiment. Methods: Analyses were based on data from The National Child Health Register that contains nationwide data on height and weight from mandatory preventive health examinations completed by school nurses or medical doctors during pre-preparatory classes (0th-3rd grade) and lower secondary education (7th-9th grade). A total of 401,517 children were included in the analyses with annual repeated cross-sectional data covering the period from 2012 to 2018. The effect of the school policy was evaluated using an interrupted time series approach comparing pre- and post-policy slopes in BMI, stratified by sex and age-group. Results: In boys, no significant differences were observed in mean BMI slopes from pre-to post-policy in either age-group. In girls, post-policy slopes were significantly higher compared to pre-policy in both age-groups (0th-3rd grade: ß:0·034 kg/m2, 95%-CI: (0·024; 0·043), p-value: <0·001; 7th-9th grade: ß:0·066 kg/m2, 95%-CI: (0·028; 0·103), p-value: 0·001). No significant differences in slopes were observed in BMI at the 90th percentile from pre-to post-policy for both sexes and across both age-groups. Adjustment for leisure-time physical activity as a potential time-varying confounder did not alter the findings. Conclusions: In conclusion, we did not detect a significant decrease in BMI levels among school-aged children following the introduction of a nationwide school policy specifying daily physical activity in school. If anything, a small positive change in BMI was observed in girls. More research is needed to understand whether structural changes similar to this requirement are able to prevent overweight and obesity in children and adolescents.

Limited associations between passive range of motion and gross motor function in ambulant/semi-ambulant children and adolescents with cerebral palsy: A cross-sectional study.

BACKGROUND AND AIM: Cerebral palsy (CP) is the most common childhood motor disability, and the Cerebral Palsy Follow-Up Program (CPUP) in Nordic countries uses a traffic light system for passive range of motion (ROM) assessment to aid interpretation and guide decisions regarding interventions. However, the arbitrary chosen ROM threshold values and their potential clinical impact are uncertain. We investigated whether lower extremity ROM values were positively associated with gross motor function and whether gross motor function scores differ between the CPUP ROM thresholds. METHODS: This was a cross-sectional analysis of CPUP data for 841 ambulatory children and adolescents with CP, at a mean (SD) age of 9 (3). Regression analyses were employed to explore the relationship between gross motor capacity and performance (using the Gross Motor Function Measure (GMFM-66) and the Functional Mobility Scale (FMS) 5/50/500 m, respectively) and lower extremity ROM, measured with a goniometer. ROM was assessed both as continuous and categorical variables. RESULTS: We found that two out of ten continuous ROM measures were positively associated with gross motor function. Limited differences in gross motor function between the ROM thresholds were seen for seven out of ten ROM measures. The CPUP traffic light thresholds primarily differentiated gross motor function between the red and green categories, predominantly for the subgroup of participants with bilateral spastic CP. CONCLUSION: Limited associations between passive ROM and gross motor function in children and adolescents with CP were observed, indicating that there is more to consider than ROM when identifying whether interventions are needed.

Recreational screen time behaviour among ambulatory children and adolescents diagnosed with cerebral palsy: A cross-sectional analysis.

AIM: To describe the recreational screen time behaviour of 8-16-year-olds diagnosed with cerebral palsy (CP) and explore associations between health-related quality of life, sleep duration and physical activity behaviour versus screen time. METHODS: This cross-sectional study used proxy-reported questionnaire data of 381 ambulatory (with or without assistance) 8-16-year-olds diagnosed with CP corresponding to Gross Motor Function Classification System (GMFCS) levels I-III. Descriptive statistics were used to report age, sex and the GMFCS level. The potential associations of health-related quality of life, physical activity behaviour and sleep duration (dependent variables) versus screen time (independent variable) were determined using multiple linear regression. Health-related quality of life was evaluated using the Pediatric Quality of Life Inventory, including seven dimensions: Daily Activities; School Activities; Movement and Balance; Pain and Hurt; Fatigue; Eating Activities; and Speech and Communication. RESULTS: The participants spent a median screen time of 3.9 h daily. The boys spent a longer screen time during weekends than the girls (p = 0.003). Boys spent more time on games (p < 0.001), whereas girls spent more time on social media and video calls (p < 0.001). Increasing age (p < 0.001) was associated with increased screen time but did not differ between the GMFCS levels. Sleep duration, perceived fatigue and perceived movement and balance correlated negatively with screen time. CONCLUSION: This study sheds light on the recreational screen time habits of ambulatory children and adolescents diagnosed with CP. Further investigation into the observed associations is warranted to investigate potential causation and relationships between sleep behaviour, quality of life and screen time behaviour.

Effect of nationwide school policy on device-measured physical activity in Danish children and adolescents: a natural experiment.

Background: A new Danish school policy with a requirement for 45 min physical activity daily during school hours was introduced in 2014. The objective of this natural experiment was to evaluate the effect of this nationwide school policy on physical activity in Danish children and adolescents. Methods: Four historical studies completed between 2009 and 2012 comprised the pre-policy study population. Post-policy data were collected in 2017/18. All post-policy schools were represented in the four pre-policy studies. Age-groups and seasons were matched. In total, 4816 children and adolescents aged 6-17 were included in the analyses (2346 pre-policy and 2470 post-policy). Children and adolescents were eligible if they had accelerometer measurements and did not have any physical disabilities preventing activity. Physical activity was measured by accelerometry. Main outcome was any bodily movement. Secondary outcomes were moderate to vigorous physical activity and overall movement volume (mean counts per minute). Findings: The school policy interrupted a linear decreasing pre-policy trend in physical activity during school hours. All activity outcomes increased post-policy during a standardized school day (8:10 am-1 pm). Increases were more pronounced in the youngest children. Specifically, we observed a daily increase during a standardized school day in 2017/2018 of 14.2 min of movement (95% CI: 11.4-17.0, p < 0.001), 6.5 min of moderate to vigorous physical activity (95% CI: 4.7-8.3, P < 0.001), and 141.8 counts per minute (95% CI: 108.5-175.2, P < 0.001). Interpretation: A national school policy may be an important strategy to increase physical activity during school hours among children and adolescents. Funding: The Danish Foundation TrygFonden has funded the PHASAR project (ID 115606).

Predictors of Physical Activity Levels in Ambulant/Semiambulant Children and Adolescents With Cerebral Palsy: A Clinical Cohort Study.

Children and adolescents with cerebral palsy (CP) show a reduced physical activity (PA) level compared with their typically developed peers. This study aimed to identify potential predictors of objectively evaluated habitual PA using data from a national clinical registry-the Cerebral Palsy Follow-Up Program (CPFP)-and proxy-reported questionnaires. Data from the CPFP database showed that female sex was associated with a lower PA level. Additional questionnaire data revealed age, popliteal angle limitation, Pediatric Outcomes Data Collection Instrument-Sports and Physical Functioning Scale score, screen time, Functional Mobility Scale score at 50 m, and fatigue as predictors. The proposed models can be used for the prediction and early detection of the PA level and consequently for the potential improvement among ambulant/semiambulant individuals with CP. Further research should investigate the predictive impact of personal, social, and environmental factors on the PA level and the gap in PA levels between girls and boys.

Tackling physical inactivity in Scandinavia: a narrative review of reviews supplemented by expert interviews.

Aims: This study aims to identify physical inactivity-related challenges and motives, based on reviews and supplemented by expert interviews with Danish national experts on physical inactivity, providing a general discussion of the subject ultimately generating knowledge useable in a Scandinavian context. Methods: This study is framed as a narrative review of scientific review literature on physical inactivity, limited to the general population. The review is supplemented by expert interviews with Danish national experts on physical inactivity. We used thematic coding of the included reviews, while using hermeneutic interpretation analysis for the expert interviews. Results: Based on 11 included reviews, we highlighted four themes based on our analysis of reviews: (a) socioeconomic determinants of physical activity; (b) life-course perspective; (c) physical inactivity and older adults aged 60+ years; and (d) intervention recommendations. The supplementary expert interviews revealed three additional themes: (a) the individual history with physical activity; (b) sporting organisation importance; and (c) society responsibility for physical inactivity. Conclusions: Collectively this study concludes, based on review and expert interviews, that a number of determinants and correlations for physical inactivity affect the individual from various socioecological levels. Based on this review, we suggest moving beyond the 'upstream' public health approach of randomised controlled trials and consider complex interventions targeting physical inactivity from several levels. Physical inactivity should be acknowledged as a 'wicked problem' that requires a systems-based approach instead of a single quick fix. Future work with physical inactivity would profit from focus on the life-course perspective, sporting clubs' responsiveness and physical literacy.

City planning policies to support health and sustainability: an international comparison of policy indicators for 25 cities.

City planning policies influence urban lifestyles, health, and sustainability. We assessed policy frameworks for city planning for 25 cities across 19 lower-middle-income countries, upper-middle-income countries, and high-income countries to identify whether these policies supported the creation of healthy and sustainable cities. We systematically collected policy data for evidence-informed indicators related to integrated city planning, air pollution, destination accessibility, distribution of employment, demand management, design, density, distance to public transport, and transport infrastructure investment. Content analysis identified strengths, limitations, and gaps in policies, allowing us to draw comparisons between cities. We found that despite common policy rhetoric endorsing healthy and sustainable cities, there was a paucity of measurable policy targets in place to achieve these aspirations. Some policies were inconsistent with public health evidence, which sets up barriers to achieving healthy and sustainable urban environments. There is an urgent need to build capacity for health-enhancing city planning policy and governance, particularly in low-income and middle-income countries.

In It for the Long Haul: RE-AIM Evaluation of a Preschool Programme Implementing and Maintaining Adult-Initiated Motor Skill Development and Physical Activity across a Two-Year Period.

Good motor skills (MS) are considered important for children's social, psychological and physical development and general physical activity (PA) levels. The Motor skill in Preschool study (MiPS) aimed to optimize children's MS through weekly PA sessions. The aim of this study is to use the RE-AIM framework to report the two-year implementation process of MiPS since the programme's initiation. Data were collected through a staff questionnaire based on the RE-AIM framework. Data were collected at three months, one year and two years after initiation. Results show that the pedagogical staff believes that the programme promotes MS in children. Implementation measures only showed medium to low fidelity concerning the core element of performing adult-initiated PA sessions with a duration of at least 45 min 4 days a week. The largest barrier was finding the time to plan these PA sessions. Still, the content of the PA sessions achieved high fidelity scores and the programme was deemed suitable for staff's everyday practice and in alignment with the stated pedagogical goals. The mandatory competence development course was highly valued as strong implementation support. It is notable that there is a large variation in the implementation among the preschools with some struggling more than others.

Exceeding 2-h sedentary time per day is not associated with moderate to severe spinal pain in 11- to 13-year-olds: a cross-sectional analysis.

Neck, mid-back and low back pain, collectively known as spinal pain, become more common with increasing age across childhood and adolescence. A common belief among the general community is that sedentary time, including screen time, in adolescents is associated with spinal pain. We aimed to investigate whether exceeding 2-h of sedentary time per day is associated with moderate to severe spinal pain in a sample of Danish adolescents aged 11-13 years. We performed a cross-sectional analysis of the SPACE study baseline data (2010). Adolescents self-reported their spinal pain (outcome) via the Young Spine Questionnaire and duration of engagement in sedentary behaviours (exposure). We provide estimates of associations as odds ratios with 95% confidence intervals, stratified by age and sex. The sample comprised 1,303 adolescents (48.7% female, mean age 12.5 years, range 10.9-14.3 years). Approximately 9 out of 10 adolescents exceeded 2-h sedentary time on weekdays outside of school (88.9%) and weekend days (89.9%). Close to one-quarter, 23.3% (95%CI: 21.0-25.6), of participants experienced moderate to severe spinal pain. We found no association between exceeding 2-h sedentary time per day and experiencing moderate to severe spinal pain; odds ratios ranged from 0.34 (95%CI: 0.04-3.20) to 4.65 (95%CI: 0.26-82.44).Conclusion: We found no association between exceeding 2- or 5-h of sedentary time per day and moderate to severe spinal pain in this sample of 11-13-year-old Danish adolescents. Our cross-sectional analysis does not consider the longitudinal or complex sequences of events necessary to address predictive or causal questions. What is Known: • Up to a third of adolescents experience moderate to severe spinal pain, predisposing them to chronic spinal pain in adulthood. • Frequent and excessive sedentary time is associated with poor overall health in adolescents; there is conflicting evidence to suggest whether it is also related to spinal pain. What is New: • We found no association between sedentary time and moderate to severe spinal pain in 11- to 13-year-old Danes.

Exploring implementation of a nationwide requirement to increase physical activity in the curriculum in Danish public schools: a mixed methods study.

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.

Predictors of physical activity levels in children and adolescents with cerebral palsy: clinical cohort study protocol.

INTRODUCTION: Children and adolescents with cerebral palsy may be trapped in a vicious circle of low physical fitness, resulting in deconditioning that causes a further decrease in physical activity (PA), a lower quality of life and an increased risk of developing non-communicable diseases. Therefore, establishing a healthy and active lifestyle during childhood is even more important for individuals with a disability. However, the factors that influence habitual PA in children and adolescents with cerebral palsy remain unknown.The present protocol outlines a prospective cohort study with the aim of investigating potential predictors of habitual PA in children and adolescents with cerebral palsy in order to provide evidence for optimising PA levels and associated overall health. METHODS AND ANALYSIS: This prospective cohort study will enrol participants with cerebral palsy between the ages of 8 and 15 years at Gross Motor Function Classification System levels I-III. Using a modified version of the International Classification of Functioning, Disability and Health model as a conceptual analytical framework, the analysis will be divided into six components and will provide predictors for habitual PA measured by accelerometry. The potential predictive variables are registry data on physical function (Danish Cerebral Palsy Follow-Up Programme); validated proxy-reported questionnaires on quality of life (Paediatric Quality of Life Inventory), overall health, pain and participation in daily activities (Paediatric Outcomes Data Collection Instrument) and supplementary questions regarding sleep, screen time and socioeconomic status. ETHICS AND DISSEMINATION: The project is approved by the Danish Data Protection Agency (19/16396) and has been declared not notifiable by the Regional Committee on Health Research Ethics, cf. Committee Act Art. 14, paragraph 1 (S-20192000-23). The study results will be published in international peer-reviewed journals, presented at international conferences, and published in a PhD dissertation. TRIAL REGISTRATION NUMBER: NCT04614207.

Barriers to, and Facilitators of, Exercising in Fitness Centres among Adults with and without Physical Disabilities: A Scoping Review.

Fitness centres are an obvious arena for performing physical activity for the general population but representation of adults with physical disabilities (AwPD) is lacking. To increase possibilities for AwPD to exercise in fitness centres together with adults without physical disabilities (AwoPD), the aim of this study was to identify, synthesise, and compare barriers to, and facilitators of, exercising in fitness centres for each group. A scoping review was conducted and data extraction of the barriers and facilitators was performed independently by two researchers on six categories of contextual factors based on the framework of Di Blasi: (1) The fitness centre setting; (2) The fitness centre user characteristics; (3) The fitness instructor/staff characteristics; (4) The fitness centre user-instructor/management relationship; and (5) The fitness/exercise characteristics. An extra category, (6) Other relationships, was added. The PRISMA Extension for Scoping Reviews was used for reporting. Of the 102 included papers, only 26 (25%) of the papers were on AwPD, which focused mainly on physical barriers (category 1: inaccessible settings). In contrast, the remaining 76 papers involving AwoPD focused primarily on facilitators (category 2: motivational factors and exercising effects). In categories 3-6, the two groups had similar results, as both groups preferred skilled instructors, a welcoming and comfortable fitness centre environment, an ability to exercise at their preferred type and level, and good social connections. Since most data were based on AwoPD, more studies on actual experiences from AwPD are needed, to reveal the facilitators/motivational factors for fitness centre use.

Fitness for all: how do non-disabled people respond to inclusive fitness centres?

BACKGROUND: Representation of people with disabilities in fitness centres is lacking, despite initiatives to promote inclusion mainly in the UK and USA. Success creating these inclusive spaces is mixed and few were crafted taking into account attitudes and biases of non-disabled co-members. Inclusive fitness centres have not gained much attention in Denmark, and the campaign 'Fitness for All - fitness for people with physical disabilities' was initiated. The aim of this study was shaped by two key questions; 1) what is the ideal fitness space from the perception of non-disabled fitness users? and 2) how might their dis/ableist attitudes negate inclusion in three future pilot inclusive fitness centres across Denmark? METHOD: Three focus groups involving 5-7 (total n = 18) adult non-disabled participants were conducted. Aged ranged between 19 and 75 years, both men and women were involved, with fitness centre experiences ranging from 0 to 20+ years. Interviews were transcribed and analysed using Malterud's four-step method of systematic text condensation. RESULTS: Of most importance was a pleasant atmosphere which should make them feel welcome and comfortable. Good social relations within the space were also highly valued. Participants welcomed people with physical disabilities but predicted many challenges with an inclusive fitness centre and expressed unconscious ableist attitudes. CONCLUSION: The current study adds essential knowledge regarding how non-disabled people perceive the ideal inclusive fitness centre. A welcoming and inviting atmosphere is essential whereas social skills, ableism, ignorance, and preconceptions are important barriers that may hinder inclusion of participants with disabilities in inclusive fitness centres.

Associations of built environment and proximity of food outlets with weight status: Analysis from 14 cities in 10 countries.

The study aimed to examine associations of neighborhood built environments and proximity of food outlets (BE measures) with body weight status using pooled data from an international study (IPEN Adult). Objective BE measures were calculated using geographic information systems for 10,008 participants (4463 male, 45%) aged 16-66 years in 14 cities. Participants self-reported proximity to three types of food outlets. Outcomes were body mass index (BMI) and overweight/obesity status. Male and female weight status associations with BE measures were estimated by generalized additive mixed models. Proportion (95% CI) of overweight (BMI 25 to <30) ranged from 16.6% (13.1, 19.8) to 41.1% (37.3, 44.7), and obesity (BMI ≥ 30) from 2.9% (1.3, 4.4) to 31.3% (27.7, 34.7), with Hong Kong being the lowest and Cuernavaca, Mexico highest for both proportions. Results differed by sex. Greater street intersection density, public transport density and perceived proximity to restaurants (males) were associated with lower odds of overweight/obesity (BMI ≥ 25). Proximity to public transport stops (females) was associated with higher odds of overweight/obesity. Composite BE measures were more strongly related to BMI and overweight/obesity status than single variables among men but not women. One standard deviation improvement in the composite measures of BE was associated with small reductions of 0.1-0.5% in BMI but meaningful reductions of 2.5-5.3% in the odds of overweight/obesity. Effects were linear and generalizable across cities. Neighborhoods designed to support public transport, with food outlets within walking distance, may contribute to global obesity control.

Will the children use it?-A RE-AIM evaluation of a local public open space intervention involving children from a deprived neighbourhood.

Knowledge on how to improve public open spaces in deprived neighbourhoods to increase active living among children is scarce and comprehensively evaluated public open space interventions are needed. Firstly, the aim was to explore if involving 39 local fifth-grade children (10-11 years old) from a deprived neighbourhood in creating playable installations in a public open space influenced their use of this space. Secondly, we wanted to explore if the Reach, Effectiveness, Adoption, Implementation and Maintenance framework (RE-AIM) was useful for evaluating different stages in the intervention project. RE-AIM was applied through a convergent mixed-methods triangulation design using survey, accelerometer, GPS, and interviews as data sources. Effectiveness outcomes revealed that on average the space was used less by the 39 children after the intervention. The implementation and maintenance dimensions revealed aspects of why most children involved in the project did not use the space after intervention. The evaluation cast light on children's perceptions of their role, and importance of maintenance when the intervention was completed. In future, all dimensions of built environmental projects would benefit from being planned and evaluated in a collaboration with all project partners using an evaluation framework integrated and applied from the beginning of the project.

Objectively measured access to recreational destinations and leisure-time physical activity: Associations and demographic moderators in a six-country study.

Within the growing body of research linking neighbourhood environmental attributes with physical activity, associations between recreational destinations and non-walking leisure-time physical activity (LTPA) are rarely studied, and to date, not across multiple cities. We examined six potential associations of objectively-measured access to private recreational facilities (e.g., fitness centres, swimming pools) and parks with adults' non-walking LTPA (e.g., swimming, cycling, tennis), using data gathered with consistent methods from adults living in international cities with a range of environment attributes. The potential effects of socio-demographic moderators and between-city variations were also examined. Data from 6725 adults from 10 cities (6 countries) were gathered. Adults were more likely to engage in non-walking LTPA if they had a greater number of private recreational facilities within 0.5 or 1 km of the home, particularly in women, and if they lived closer to a park. The amount of non-zero LTPA was only associated (positively) with the number of recreational facilities within 1 km. Relationships between amount of LTPA and park proximity appear complex, with likely contextual and cultural differences. Improving access to private recreational facilities could promote non-walking LTPA, especially in women.

Copenhagen Consensus statement 2019: physical activity and ageing.

From 19th to 22nd November 2018, 26 researchers representing nine countries and a variety of academic disciplines met in Snekkersten, Denmark, to reach evidence-based consensus about physical activity and older adults. It was recognised that the term 'older adults' represents a highly heterogeneous population. It encompasses those that remain highly active and healthy throughout the life-course with a high intrinsic capacity to the very old and frail with low intrinsic capacity. The consensus is drawn from a wide range of research methodologies within epidemiology, medicine, physiology, neuroscience, psychology and sociology, recognising the strength and limitations of each of the methods. Much of the evidence presented in the statements is based on longitudinal associations from observational and randomised controlled intervention studies, as well as quantitative and qualitative social studies in relatively healthy community-dwelling older adults. Nevertheless, we also considered research with frail older adults and those with age-associated neurodegenerative diseases, such as Alzheimer's and Parkinson's disease, and in a few cases molecular and cellular outcome measures from animal studies. The consensus statements distinguish between physical activity and exercise. Physical activity is used as an umbrella term that includes both structured and unstructured forms of leisure, transport, domestic and work-related activities. Physical activity entails body movement that increases energy expenditure relative to rest, and is often characterised in terms of intensity from light, to moderate to vigorous. Exercise is defined as a subset of structured physical activities that are more specifically designed to improve cardiorespiratory fitness, cognitive function, flexibility balance, strength and/or power. This statement presents the consensus on the effects of physical activity on older adults' fitness, health, cognitive functioning, functional capacity, engagement, motivation, psychological well-being and social inclusion. It also covers the consensus on physical activity implementation strategies. While it is recognised that adverse events can occur during exercise, the risk can be minimised by carefully choosing the type of activity undertaken and by consultation with the individual's physician when warranted, for example, when the individual is frail, has a number of co-morbidities, or has exercise-related symptoms, such as chest pain, heart arrhythmia or dizziness. The consensus was obtained through an iterative process that began with the presentation of the state-of-the-science in each domain, followed by group and plenary discussions. Ultimately, the participants reached agreement on the 30-item consensus statements.

Protocol for evaluating the impact of a national school policy on physical activity levels in Danish children and adolescents: the PHASAR study - a natural experiment.

BACKGROUND: In 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. METHODS: The 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. DISCUSSION: The 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.