(2024) 24:561
Gasser et al. BMC Pediatrics
https://doi.org/10.1186/s12887-024-05034-0

BMC Pediatrics

STUDY PROTOCOLOpen Access

Increasing adolescents’ physical activity
levels through a comprehensive school‑based
physical activity program: study protocolof the cluster randomized controlled trial Active
SchoolMarion Gasser1*, Andrea‑Maria Nadenbousch2*, Fabienne Egger1, Mario Kamer1,2, Stefan Valkanover1,2 andMirko Schmidt1

Abstract
Background The positive effects of regular physical activity on children and adolescents’ physical and mental healthare well-established. Despite these health benefits, most Swiss adolescents do not meet WHO’s recommended levelof physical activity, which includes a daily minimum of 60 min of moderate-to-vigorous physical activity. Due to their
inclusivity, schools are identified as a key setting to promote physical activity. Recently, the comprehensive school
physical activity program (CSPAP), in which teachers as physical activity leaders (PALs) play a crucial role to advance
comprehensive school-based physical activity promotion, has been discussed. However, such comprehensive
approaches are still lacking in Switzerland, and specific PAL trainings do not exist. Therefore, the aim of this study
is to implement and evaluate Active School, a comprehensive school-based physical activity program for Swiss secondary schools with integrated PAL training.
Methods/design A cluster randomized controlled trial (RCT) involving 12 secondary schools (6 experimental, 6
waiting control schools) will assess baseline data and effectiveness of Active School at 12 and 24 months. Active
School includes five components based on the CSPAP. Each school is encouraged to set individual physical activity goals in this regard. This process is guided by the PALs, who will participate in professional development training
before and during Active School implementation. As a primary outcome, students’ moderate-to-vigorous physicalactivity will be assessed via accelerometers. As secondary outcomes, inactivity, light physical activity, step counts,
aerobic fitness and coordination will be measured, and students’ general wellbeing, learning behavior, and multiple
psychosocial measures related to physical activity will be assessed by questionnaires. The effectiveness evaluationis accompanied by a process evaluation that focuses on the implementation outcomes of dose of delivery, reach,feasibility, and sustainability. A mixed methods approach, including ripple effect mapping, will be employed to reconstruct and understand the implementation process.

*Correspondence:
Marion Gasser
marion.gasser@unibe.ch
Andrea‑Maria Nadenbousch
andrea-maria.nadenbousch@phbern.ch
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Gasser et al. BMC Pediatrics(2024) 24:561

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Discussion This study will be the first to implement and evaluate a CSPAP in the Swiss school system. The specific
PAL training and the simultaneous application of effectiveness and process evaluation are considered strengthsof the study.
Trial registration German Clinical Trials Register (DRKS00033362). Date of registration: January 25, 2024. Retrospectively registered.
Keywords Comprehensive approach, Physical activity, Secondary school, Adolescents, Physical activity leader,
Process evaluation, Effectiveness evaluation

BackgroundChildren and adolescents are becoming increasingly
sedentary, with their physical activity behavior being
characterized by a lack of exercise [1]. Regular physicalactivity declines, especially in adolescence. As a result,
80% of adolescents do not meet the daily physical activity recommendations of 60 min of moderate-to-vigorous
physical activity (MVPA) [2]. This global trend is also
evident in Switzerland, as over half of Swiss adolescents
fail to meet the daily physical activity recommendations[3]. The prevalent physical inactivity pattern is worrying because it is associated with far-reaching negative
effects on adolescents’ health, subsequently leading tohigh healthcare costs for society [4]. Moreover, inactivity and irregular physical activity in adolescence are often
connected with inactivity in adulthood [5], increasing therisk of chronic diseases later in life [6]. It is well known
that the health benefits of regular physical activity foradolescents are extensive including reduced risk for obesity as well as improved physical fitness, cognitive functions, and mental health [7, 8].
Since adolescents spend a considerable part of their day
at school, schools seem to play a pivotal role in promoting
physical activity for all students. This is also supported bystudies that have identified schools as a key setting withpotential for high impact [9]. According to internationalguidelines, it is recommended that students participate ina minimum of 30 min of MVPA at school, which includes
physical education classes [10]. Unfortunately, most
schools do not provide enough opportunities for physical activities. Results of a European cross-sectional study
indicate that Swiss adolescents spend 65% of their school
time sitting and only 5% in MVPA, which is below therecommended average of 30 min [11], highlighting theneed for effective interventions for this population.
In recent years, many school-based physical activity
interventions have been implemented [12]. Althoughschool-based physical activity interventions are considered effective [13, 14], sustaining positive effects over an
extended period remains challenging [15, 16]. Thus, theKISS study in Swiss schools showed significant increases
in MVPA during the intervention year [17] but failed tomaintain these effects in the long term [18]. However,this intervention was relatively controlled by researchers,
who prescribed the physical activity measures with little
room for adaptation.
To address these challenges, it is crucial to focus on
the adaptability of interventions to ensure their longterm success [19]. Physical activity interventions often
encounter numerous barriers, particularly at the teacher
level, including lack of time, confidence, motivation, andresources to deliver physical activity measures [20–22].
Therefore, interventions should be designed to fit theunique contexts of individual schools and integrate stakeholder perspectives in the planning stages [23]. This
ensures that the intervention meets the specific needs
and capacities of each school, facilitating better buy-inand sustainability.
In the recent scientific discourse, comprehensive
approaches are therefore increasingly discussed. For
example, the comprehensive school physical activity program (CSPAP) promoted by the US Center for Disease
Control and Prevention represents such a comprehensive approach by addressing three important aspects [24]:1) Physical activity leaders (PALs; experienced physicaleducation teachers recommended) play a central role[25] and are responsible for physical activity promotion, support, and accompaniment of all participants.
Internal leadership appears to be a critical factor in the
successful implementation of physical activity measures[20]. 2) Physical activity promotion can be addressed ina variety of school settings since an expansion of physicalactivity options is considered a key element in increasing students’ physical activity levels [26]. 3) The schools
are encouraged to develop individually tailored physicalactivity goals and subsequent possibilities for implementation since suitability and autonomy in program designand delivery seem to increase the engagement and motivation of the school staff [23, 27].
In English-speaking countries, such comprehensive
approaches are already more established, with someevidence supporting its effectiveness in enhancing daily
physical activity in youth [28–31]. For instance, the comprehensive project PA4E from Australia significantly
increased the MVPA level of adolescents after 12 monthsof program duration [28]. These effects persisted even

Gasser et al. BMC Pediatrics(2024) 24:561

after 24 months [29]. Furthermore, it has been shownthat increased physical activity also improves a wide
range of outcomes. Therefore, previous findings suggest that comprehensive school-based physical activity
interventions can also lead to positive effects in physicalfitness, motor skills, wellbeing, learning behavior, andsocial-emotional learning, which is crucial for a positiveclass- and school climate [32–34]. In German-speaking
countries, however, CSPAPs are still missing. In Switzerland, particularly, physical activity programs are often
implemented at the level of individual classes rather thanat the school level [35, 36]. Thus, there is a need to start
implementing comprehensive school-based physicalactivity programs in the Swiss school system.
To truly achieve positive effects of comprehensive
approaches, it is also essential to consider their challenges [37]. Special attention must be given to internal
leadership, specifically the PALs [24, 38]. Due to their
new roles and responsibilities, they need to develop
leadership skills beyond their regular teaching profession, which altogether often results in insufficient time
for their normal duties [39]. Therefore, it is crucial that
PALs receive adequate support from the school environment as well as external resources [40]. Emphasis shouldbe placed on the importance of professional development(PD) trainings [41] with integrated and regular mentoring [37], as studies have shown that trained PALs implement significantly more physical activity opportunities[42].
Recognizing the positive impact of a specific PAL PD
training, it appears crucial to incorporate such a component when implementing CSPAP in the Swiss school
system.
Isolated PAL PD trainings exist [25], but they have predominantly been designed for the Anglo-American context. However, differences in culture and language preventthese programs from being directly applied to the Swiss
school system, necessitating adaptations [13, 14, 43].
Concerning the evaluation of comprehensive approaches,several methodological issues must be considered becauseof their complex intervention characteristics [44, 45]. Dueto the multi-layered nature of a CSPAP and its high flexibility, implementation varies greatly across schools, which
is important to consider as implementation effectiveness inphysical activity interventions is known to be linked withpositive outcome measures [20, 32]. Thus, to make an accurate statement about the program’s (in)effectiveness, it isrecommended that additionally process evaluations be
conducted, which provides information on understanding
the outcomes by a more detailed analysis of how the program works and why [15, 37]. To do so, an understanding of
the specific implementation in each school is required [20].

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Therefore, the description and assessment of the implementation are necessary and involve the identification ofoutcomes and additional determinants at the support anddelivery levels of the individual school [46, 47].
Based on recent findings, we will implement a CSPAP
called Active School in the Swiss secondary school system
to increase students’ physical activity, which will consistof a specified PAL PD training. To evaluate Active School
and analyze whether the program was implemented
as intended, we are conducting the evaluation in two
strands: the effectiveness evaluation, which measuresphysical activity behavior at the student level, and theprocess evaluation, which analyzes specific variables atthe support and delivery systems.

Methods and design
Study aims and hypotheses

This study has two purposes:
First, this study will examine whether the comprehensive school-based physical activity program
Active School effectively promotes increased physicalactivity in adolescents (effectiveness evaluation). It is
assumed that Active School will result in an increasein the primary outcome MVPA level among students
compared to the waiting control schools and that thisincrease will be sustained after 12 and 24 months ofActive School implementation. In addition, it will be
examined whether Active School may exert a positiveeffect on the secondary outcome measures, which
can additionally be influenced by the intervention,
namely inactivity, light physical activity, step counts,
aerobic fitness, coordination, self-reported physical activity, general wellbeing (subjective wellbeing,classroom climate, school wellbeing), and learning
behavior. To gain a deeper understanding of how
physical activity is influenced, we also assess psychosocial factors (physical self-concept, motivation forexercise, physical activity environment in school) that
may mediate physical activity participation [48–50].
Second, the study will investigate the implementation
process to understand how the schools implement
Active School (process evaluation). The implementation of Active School is based on the framework for
effective implementation [47]. Since schools independently plan, conduct, and evaluate their physicalactivity measures, the entire internal development
and implementation process will be systematically
documented and reconstructed to enable the processevaluation in each school. The process evaluation will
focus on the implementation outcomes, dosage ofdelivery, reach, feasibility, and sustainability among

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Fig. 1 Intervention and measurement timeline. Note: Q1-Q4 = quarter 1-quarter 4, ES1 & 2 = experimental schools cohort 1 & 2, CS1 &2 = waiting control schools cohort 1 & 2, PP = Active School preparation phase, IP = Active School implementation phase, PE = process evaluation,
EE = effectiveness evaluation, W = PAL workshops, REM = ripple effect mapping

the support and delivery systems of the schools [46].
Further implementation determinants related to context, provider, program characteristics, and characteristics of the program delivery and support systems
will be analyzed [47].
Study design

A cluster randomized controlled trial (RCT) involving
12 secondary schools (1:1 allocation: 6 experimental, 6
waiting control schools) will be conducted for the effectiveness evaluation. Two cohorts, each comprising six
schools (3 experimental and 3 waiting control schools),
will be recruited, initiating their participation in Active
School with a one-year offset (see Fig. 1). The primaryand secondary outcomes will be measured at baseline

assessment (T2), after 12-month post assessment (T4)
and at a 24-month follow-up assessment (T6). The six
schools of the waiting control group will continue theirroutine as usual and are not allowed to implement any
specific school programs to promote physical activity.
The schools can access all project-specific materials at
the end of Active School, and the teachers are given theopportunity to attend the same PAL PD training. A waiting control design was deliberately chosen to mitigate thecontrol school’s disappointment over not participatingin the project, thereby maintaining their motivation forassessments.
Qualitative and quantitative data collection will be
conducted at the 6 experimental schools for the process evaluation. At the beginning of the Active School
preparation phase (T1), the personal, spatial, temporal,
and financial resources for promoting physical activity

Gasser et al. BMC Pediatrics(2024) 24:561

within the school will be assessed. After a 6-month (T3)
and 18-month (T5) Active School implementation phase,
data on the implementation outcomes as well as further
implementation determinants will be collected through amixed-methods data collection, using document analysis,
ripple effect mapping (REM), semi-structured interviews,
and questionnaires.
Setting

Active School will be conducted in three different regionsof the Swiss canton of Bern (Bernese Oberland, Bernese
Mittelland, Bernese Emmental). These regions are geographically widely dispersed and include urban areas
with cities and regional/rural areas. The canton of Bernwas chosen for the study because its geographical characteristics reflect a representative image of Switzerland.
Secondary schools in the canton of Bern are aimed atstudents aged 12–16 (7th to 9th grade) and run for twosemesters per calendar year. Swiss secondary schools are
obliged to offer students three lessons of physical education (135 min in total) per week. The canton of Bern recommends the implementation of additional school-based
physical activities, but these are not mandatory.

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projects in the area of physical activity promotion; (6)schools must have at least two interested teachers who
are willing to take on the role of PAL. Whether the first
four criteria are met is determined based on publicly
available data. The fifth and sixth criteria are evaluatedbased on contacts with school principals during recruitment. Interested schools will be contacted by the project
coordinator, who will then hold individual meetings withthe school principals and potential PALs.
After recruiting, stratified randomization will be carried out through the research team with one stratum andwith the requirement of an even distribution of schools
from diverse regions of the canton of Bern (Bernese
Oberland, Bernese Mittelland, Bernese Emmental) to theexperimental schools and the waiting control schools.
The two strata will be defined according to school typology based on the school’s geographical location. Stratum
A: rural school; Stratum B: urban school. Starting withstratum A, schools will be randomly assigned to either
the experimental or waiting control schools. After randomization, an agreement will be signed with all school
principals in which the form of collaboration with theresearch team is set out for the project’s duration. The
first part of the RCT is shown in Fig. 2.

Sample size

We used the R package powerlmm [51] to conduct a
power analysis for a longitudinal multilevel model. Basedon previous studies analyzing the effectiveness of comprehensive approaches, we set the effect size for differences in MVPA level (primary outcome) between study
arms at 0.25 [31]. The baseline intraclass correlation coefficient (ICC) at the school level was set to 0.01 [52] and at
the student level to 0.70 [53]. Based on a 65% rate of thecohort contributing valid data at the 24-month follow-up[54] the dropout rate was set to 0.35. With six schools perarm, a minimum of 45 students per school and tree time
points analysis indicated a power of 0.81. Hence, it will benecessary to recruit a total of 12 schools (6 experimental and 6 waiting control schools) and a minimum of 540
students in total.
School recruitment, selection and randomization

Active School will be advertised through various channels(e.g., newsletters from the Bern University of Teacher
Education, presentations at cantonal sports teacher training courses). The cantonal sports government will also
support the recruitment by sending a project invitation
to all eligible secondary schools in Bern via the cantonale-mail database. The schools must fulfill various criteria
to be included in the project: (1) cantonal public or semipublic schools; (2) students in grades 7–9; (3) at least twoclasses per school level; (4) no talent- /art- / or boarding schools; (5) no participation in other major school

Intervention

Active School is based on the CSPAP promoted by the US
Center for Disease Control and Prevention [24]. Active
School, therefore, incorporates five core componentsof physical activity promotion in school, focusing on 1)
Physical Education, 2) Physical Activity During School,3) Physical Activity Before and After School, 4) Staff
Involvement, and 5) Family and Community Engagement. In implementing Active School, each school canprioritize and enhance physical activity in any of thefive core components. This allows schools to tailor theirapproach autonomously based on individual goals andneeds, promoting a customized and adaptable strategy
to foster physical activity within their unique context.
PALs will undergo the PAL PD training provided by the
research team to be prepared for their role as the leadersof Active School at their schools. Subsequently, teachersat the respective school will be guided and supported by
the PALs in implementing various physical activity measures derived from the school’s individual goals.
Physical Activity Leader (PAL)

Regarding the PALs tasks, two areas can be distinguished: creating facilitating conditions for the implementation of measures promoting physical activity
in the areas explained above (support system) andplanning, executing, and evaluating these measures

Gasser et al. BMC Pediatrics(2024) 24:561

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Fig. 2 Flow Diagram of the RCT​

involving all school stakeholders (delivery system).
For the implementation of Active School, PALs apply
several strategies that include implementation, capacity-building, dissemination, and integration [55]. The
PALs should employ these strategies to establish a support system for the teachers and staff at their school,
enabling the implementation of physical activity measures for students (see Fig. 3).
Each experimental school must provide two PALs
who take on the role together. All PALs are regularteachers from the respective school who should becommitted and motivated for the new task, and ideally familiar with physical education as well as theclassroom setting. Like the schools, PALs commit to
implementing Active School at their respective schoolsfor 2.5 years. Additionally, PALs will be compensatedfor their work with one paid hour per week. This
compensation ensures that they are adequately supported and motivated to fulfill their responsibilities
effectively. Each experimental school also compiles
a physical activity committee (PA committee), which
the PALs lead. The PA committee consists of up to fivedifferent representatives of the school (e.g., interested

teachers, school principals, students, and janitor). It
supports the PALs in establishing good conditions forthe implementation of Active School within the support and delivery systems.
PAL professional development training

The PAL PD training will comprise a) the transferof strategies for implementing specific school-based
physical activity promotion measures and b) considerations of strategies for supporting the delivery of thesemeasures. Therefore, the PAL PD training consists of 4
workshops, regular exchanges with the research team,and technical support provided by the research team.
The 4 workshops take place over a year and will be conducted in person, bringing together all PALs from thedifferent schools. This group setting is chosen to facilitate personal contact and beneficial exchanges among
the PALs. Each workshop will last for 3 to 4 h and will
be scheduled on a non-school afternoon. The workshops are designed to build knowledge and develop
strategies that can be applied in practice. This handson approach [41] ensures that participants are not only
learning theoretical concepts but also gaining practical

Gasser et al. BMC Pediatrics(2024) 24:561

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Fig. 3 Logical Model Active Schoolskills that they can implement in their daily work settings. During the preparation phase (PP, see Fig. 1), twoworkshops take place to prepare structures for the later
implementation at the schools. There is no deliveryof measures for physical activity promotion in the PP.
During the implementation phase (IP, see Fig. 1), two
additional workshops take place. From the beginning of
this phase, measures will be delivered within the corecomponents of Active School.
The workshops are based on Meyers and colleagues’
Quality Implementation Framework [56]. During theworkshops, PALs will learn the following strategies [55]:1) Implementation process strategies– Conducting a needs-assessment (e.g., the wishes,
concerns and needs of the school staff and students)– Building a physical activity committee– Defining visions and objectives– Selecting, adapting, and planning physical activity
promotion measures that fit the school’s needs– Evaluating processes and outcomes2) Capacity-building strategies– Organizing training for teachers– Supporting implementation by technical assistance– Promoting peer networking and cooperation
3) Dissemination strategies– Developing and promoting physical activity measures– Development, procuring, and providing materials
4) Integration strategies– Setting up a reminder system for the delivery system– Scheduling specific periods or windows forexchange
At the first workshop, PALs will be briefed on Active
School and implementation strategies to conduct initial considerations regarding their school setting. During the second workshop, PALs will acquire additional
implementation, capacity-building, and dissemination
strategies to create structures for implementation at theirschool. The third workshop will focus on integration anddissemination strategies on the one hand and discuss
ongoing work at the school on the other. The PALs shouldbe empowered to maintain and expand the structures forsupport once the implementation has begun. The fourth

Gasser et al. BMC Pediatrics(2024) 24:561

workshop will focus on evaluating and improving theinternally implemented measures at the schools.
Regular exchange and collaboration between the PALs
and the research team are planned throughout the entire
project duration. In the first year, this exchange will occur
during the workshops and individually scheduled online
meetings, aiming to support the PALs in implementing the Active School effectively. In the following years of
the IP, biannual meetings will be scheduled to support
the exchange between the schools. Additionally, each
PAL will be assigned a mentor from the research team
who will serve as their primary contact for any questions
or concerns. This mentoring system is crucial as it provides ongoing support and guidance, ensuring that PALs
feel confident and capable in their roles [41]. Mentoringhelps to enhance the implementation of physical activity
programs by offering personalized and regular assistanceand ensuring consistency in program delivery through thesetting of milestones [37]. This support system is vital for
maintaining motivation, addressing challenges promptly,
and fostering a collaborative environment conducive to thesuccessful promotion of physical activity within schools.
Technical support will be provided by the researchteam on the levels of the school’s support and delivery
system. PALs have access to digital templates for planning, conducting, and evaluating the school’s measures,
which support the execution of implementation strategies. To foster physical activity measures, schools canaccess an extensive online collection of materials andideas for school-based physical activity promotion in all
five core components of the Active School. This collection
is intended to facilitate the application of capacity-building and dissemination strategies.
Participants
Effectiveness evaluation

According to the power analysis, at least 540 students(12–16 years) will be recruited. All students from the ­7th
grade at each experimental and waiting control school
are eligible to participate in the RCT measurements andwill be invited to take part in the study. The students
therefore complete the baseline assessment (T2) in the­7th grade, the post assessment (T4) in the 8­ th grade, andthe follow-up assessment (T6) in the 9­ th grade (see Fig. 2).
Students who are injured or sick and consequently unable
to engage in their usual physical activity routines will not
be included in the analysis for the respective measurement time point.
Process evaluation

To accurately map the implementation process throughActive School, various stakeholders engaged in designing

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and delivering measures within the school’s support anddelivery systems will be involved in the process evaluation. 12 PALs (two in each experimental school), 6 principals, and the members of the 6 PA committees (one ineach experimental school) will be included in the process evaluation. In addition, all teachers from the experimental schools will be invited to complete an online
questionnaire to gain a deeper understanding of theirperspectives.
Procedure
Effectiveness evaluation

The research team will provide a consent form to thestudents, which requires a parental signature (see ethics
approval and consent to participate for further detail). To
motivate the students to wear the accelerometer, they will
get incentives at each measurement time point if they
adhere to the wearing conditions. Research assistants,
who will be blinded about the group assignments of theschools, will be trained to practice the standardized test
procedure to collect all outcome variables. Also, the statistician will remain blind to the study group by utilizing
various treatment codes.
Process evaluation

Before the commencement of the implementation process, Active School and the planned surveys will be introduced to the teachers at all experimental schools, andthe principals will obtain their consent. The collaboration between the research team and schools will be initiated by signing an agreement in which the Principals andPALs commit to implementing Active School and participating in process evaluations.
The process evaluation consists of qualitative datacollection through ripple effect mapping (REM), semistructured interviews, and quantitative data collection through a teacher questionnaire. The REMs will
be conducted on-site with the entire physical activity
committee at each experimental school. The previously gathered documents (e.g., PAL protocol) will be
used to create a timeline on Miro [57], including key
events of the implementation process. This timeline
is utilized during the REMs to document the school’s
implementation process. After the REM, the implementation process of each experimental school will
be digitally mapped on Miro. Research assistants will
undergo training in advance to practice the mapping
process during the REM workshops. For the semistructured interviews, appointments with principals
and PALs will be scheduled following the REM. Ifnecessary, additional PA committee members will beinterviewed for a comprehensive understanding of theGasser et al. BMC Pediatrics(2024) 24:561

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Table 1 Students measurements at each time point (following
SPIRIT template [59])Time Point
T2

T4

T6

x

x

x

Primary Outcome
MVPA
Secondary Outcomes
Inactivity

x

x

x

Light Physical Activity

x

x

x

Step Counts

x

x

x

Aerobic Fitness

x

x

x

Coordination

x

x

x

Self-reported Physical Activity

x

x

x

Subjective Wellbeing

x

x

x

Classroom Climate

x

x

x

School Wellbeing

x

x

x

Learning Behavior

x

x

x

Physical Self-Concept

x

x

x

Motivation for Exercise

x

x

x

x

x

x

x

Physical Activity Environment in SchoolStudents characteristics
Socioeconomic Statusx

Family Health Climate

x

BMI

x

MVPA Moderate-to-vigorous physical activity, BMI Body mass index

implementation process. The interviews will be conducted on-site at the school and documented throughaudio recordings. For the transcription of the interviews, the AI-based software noScribe [58] is used.
The teacher questionnaire will be integrated into aschool internal teacher meeting.
Measurements
Effectiveness evaluation

At all three measurement time points (T2, T4, T6), thestudents’ objective physical activity, aerobic fitness andcoordination will be measured, and the student questionnaire will be conducted (see Table 1).
Objective physical activity

Objective physical activity will be assessed with the
GENEActiv accelerometer (Activinsights Ltd, Kimbolton, UK). Students will wear the GENEActiv accelerometer continuously for seven days, i.e., 24 h per day, on
their non-dominant wrist. Physical activity data analysis will include participants with at least 10 h of wear
time per 24-h period on at least four days [53]. GENEActiv accelerometers are validated for the adolescentage group [60] and have been used in various studies
focusing on school-based physical activity promotion[30, 61]. Since the devices are waterproof and highly
durable, they can be worn during all activities. Students will be instructed to keep the accelerometer onthroughout the entire measurement week. The following variables will be recorded with the GENEActiv
devices: MVPA, inactivity, light physical activity, andstep counts. To define the various intensity levels, thecut points from Phillips et al. [60] will be used, as they
are best suited to the age range of our study population.
Student characteristics

Students will be asked to report their date of birth andsex. Standing height and weight will be measured using
standardized procedures. Weight will be measured to thenearest 0.1 kg using a digital scale (EBS002K, Esperanza).
Height will be measured to the nearest 0.1 cm using a
portable stadiometer (Anthroflex, NutriActiva, Germany). Participants will be asked to remove their shoes
and any heavy clothing before measurements are taken.
Body mass index (BMI) will be calculated, taking into
account sex and age [62]. The socioeconomic status of
the students will be assessed using the Family Affluence
Scale III (FAS III) [63] and the family health climate using
the Family Health Climate Scale (FHC-scale) [64].
Aerobic Fitness and coordination

Aerobic fitness will be assessed by the 20-m shuttle run
test [65]. To measure coordination, the test item jumping sideways from the German Motor Test 6–18 (GMT6–18) will be used [66]. The trained research assistants
will conduct the testing. It will take place during a physical education class in the gymnasium, with each session
accommodating a class group. Each research assistantwill be responsible for approximately 5 students, recording the results individually on an evaluation sheet.
Students questionnaire

Self-reported physical activity, general wellbeing, learning behavior, and multiple psychosocial measures related
to physical activity will be assessed using the students’questionnaire. Self-reported physical activity will beassessed using the MoMo Physical Activity Questionnaire (MoMo-PAQ) for adolescents, which measuresphysical activity in different settings [67]. In this study, we
considered the settings overall physical activity (2 items),
school (9 items), sport club (2 items), and leisure-time (3items). Four additional specially developed items will be
used to delve more specifically into physical activity inthe educational setting. These items inquire how often

Gasser et al. BMC Pediatrics(2024) 24:561

students engaged in the following physical activities atschool during the preceding school week: learning while
standing, physically active learning, movement breaks,
and physical activity homework. General wellbeing will
be assessed using the KIDSCREEN-10 [68], which measures subjective wellbeing (10 items); the classroom climate scale of the Questionnaire for the Assessment of
Emotional and Social School Experiences (FEESS 3–4)
[69], which measures the classroom climate (11 items);
and the wellbeing in school scale of the Linzer Questionnaire on School and Class Climate Assessment (LFSK
4–8) [70], which measures school wellbeing (2 items).
Learning behavior will be assessed with two subscales(Endurance, Concentration) of the Self-report Checklist
for Social and Learning Behavior (SSL) (4 items each)[71]. Regarding psychosocial measures related to physical activity, we will assess physical self-concept using thePhysical Self-Concept in Children Questionnaire (PSKK) (21 items) and the Physical Self-Description Questionnaire (PSDQ-S) (subscale physical self-esteem, 3 items)[72, 73]; motivation for exercise using the Behavioral
Regulation in Exercise Questionnaire 2 (BREQ-2) (19items) [64, 74]; and school physical activity environment
using the Questionnaire Assessing School Physical Activity Environment (Q-SPACE) (13 items) [75].
Process evaluation

The variables collected before implementation (T1) serve
to determine the initial situation of the schools. These
results will be fed back to the PALs during the PD training, thereby supporting them in planning appropriate
measures that meet the specific needs and conditions
identified at their schools. Based on these T1 conditions,the implementation outcomes and determinants are analyzed at the measurement points T3 & T5 (see Table 2).
Principal questionnaire

We will assess principals’ perceptions of school-based
physical activity promotion using a self-developed questionnaire that measures opportunities for physical activity promotion of the five core components (see chapter
intervention) as well as guidelines, leadership, andrequirements for school-based physical activity promotion. The questionnaire items are based on the CSPAPQ questionnaire [76] and the Creating Active Schools
Organisational Change Questionnaire [77].

Page 10 of 16

assess PAL’s physical activity background, their attitudes
toward sports participation will be measured using theQuestionnaire for Measuring Attitudes Toward Sports
Participation [78]. Additionally, we will inquire PALs
about their task-specific self-efficacy using the German
version of the Norwegian Principal Self-Efficacy Scale(SWE) [79]. The intro sentence and the wording of thescale were specifically adapted for the tasks of the PALs.
Teacher questionnaire

The teacher questionnaire serves as a comprehensive
instrument for gathering various pertinent information related to school-based physical activity promotion
among teachers from experimental schools. Therefore,teachers will provide the same demographic information
as the PALs. To assess teachers’ physical activity background, their attitudes toward sports participation will
be measured using the Questionnaire for Measuring
Attitudes Toward Sports Participation [78], and theirself-reported physical activity will be measured using theGodin-Shephard Leisure-Time Physical Activity Questionnaire (GSLTPAQ) [80]. Teachers’ self-efficacy in providing classroom physical activity will be measured using
the Teacher Efficacy Towards Providing Physical Activity
in Classroom Scale (TETPPACS) [81]. To measure teachers’ implementation of classroom physical activity, four
additional specially developed items based on Bund et al.
[82] will be used regarding the frequency of standing
learning, movement breaks, physically active learning,and physical activity homework during the past school
week. Furthermore, the implementation of school-based
physical activity promotion will be assessed using the
Health Promotion School Implementation Instrument(HPS) [83]. The intro sentence and the wording of thescale were specifically adapted to the topic of schoolbased physical activity promotion.
Additionally, teachers will be queried with project-specific items. Therefore, their specific readiness for change
and their intention to change will be measured [84].
Teachers’ perceived acceptability and appropriateness of
Active School will be measured using the German versionof the Acceptability of Intervention Measure (AIM) andthe Intervention Appropriateness Measure (IAM) [85].
Their motivation toward Active School will be assessedusing the Work Task Motivation Scale for Teachers(WTMST) [86]. Furthermore, job satisfaction will beassessed using a single item [87].

PAL questionnaire

The PAL questionnaire serves to obtain a descriptive
characterization of the PALs. Therefore, PALs will provide demographic information, including age, sex, yearsof teaching experience, educational qualifications, andwhether they are certified physical education teachers. To

Document analysis

The documents created by the PALs and the PA committees provide insights into the ongoing work and theestablishment of support and delivery systems of theSupporting opportunities of the school, including guidelines/leadership/requirements: all Principals (T1)

Principal questionnaire

Personal judgment regarding the current establishment of a support system,
including the personal role in the process/dose of delivery/reach/feasibility/
implementation determinants based on the process mapping: all principals, all
PALs, additional key members of the physical activity committees (T3, T5)

Semi-structured interviews

PALs Physical activity leaders, PA Physical activity

Activities and decisions in the support system, implemented strategies includ- Activities and decisions in the delivery system, implemented PA measures,ing implementation/capacity-building/dissemination/integration strategies,
facilitators, and barriers for the implementation: all physical activity committees
and facilitators, and barriers for the implementation: all physical activity com(T3, T5)
mittees (T3, T5)

Ripple effect mapping

Personal judgement regarding the current implementation of PA measures,
including the personal role in the process/dose of delivery/reach/feasibility/
implementation determinants based on the process mapping: all principals, all
PALs, further key members of the physical activity committees (T3, T5)

Protocol including actions and decisions within the physical activity committee, further documents created during the implementation processby the physical activity committee: all available documents (T3, T5)

Teacher characteristics including background/attitudes towards sports participation/self-reported physical activity/self-efficacy, level of implementation,and project specific items including readiness for change/intention to change/
acceptability/appropriateness/motivation/job satisfaction: all teachers (T1, T3,
T5)

PA opportunities of the school including core components /guidelines/requirements: all Principals (T1)

Delivery system

Document analysis

Teacher questionnaire

Physical activity leader questionnaire PALs characteristics including background/attitudes towards sports participation/self-efficacy: all PALs (T1)

Support system

Data collection methods

Table 2 Data collection methods of the process evaluation

Gasser et al. BMC Pediatrics(2024) 24:561
Page 11 of 16

Gasser et al. BMC Pediatrics(2024) 24:561

experimental schools, including information on decisions, implemented measures, and implementation challenges [88]. All created documents will be digitally stored
for access by the research team and included in qualitative analysis. Using the provided templates, the PALs will
protocol continuously all meetings with the principal,
agendas, and decisions from PA committee meetings,
collaboration and planning sessions with teachers, andother important events within Active School. Furthermore, the tasks of the PA committee will be documented,
along with their allocation to individual committee
members. Additionally, the needs-assessments, visions,
goals, measures, evaluation tools, and results developedin the PA committee in collaboration with teachers are
documented.
Ripple Effect Mapping (REM)

REM is a qualitative approach to gathering data on
the broader impacts of an intervention and the implementation process in collaboration with the implementation’s stakeholders [89, 90]. REM is designed
to reveal a wider spectrum of a program’s intended
and unintended effects. This is particularly crucial incomprehensive system programs and situations whereinterventions are adaptable, evolving, and collaboratively produced [90]. Hence, this method is suitable for
evaluating the implementation of Active School. The
REM takes place during a meeting led by the researchteam. To gain insight into the implementation processof Active School, the REM will be carried out with the
PA committees of the experimental schools. The goal
is to generate a visual representation of the implementation process in the support and delivery systemsof the schools. The approach proposed by Chazdon
et al. [89] will be adapted to ensure the reconstruction of the processes in the support and delivery systems. The sessions consist, therefore, of the following
four steps: team-based discussion and mapping of allactivities and impacts regarding the support system of
the school, team-based discussion, and mapping of allactivities and impacts regarding the delivery systems,
further reflection on the implementation process to
identify facilitators and barriers, conclusions on thecurrent implementation process and outlook. With
REM, the activities and impacts of the PA committee
implementing Active School will be visually mapped
along the timeline based on the four PAL PD training
workshops and the collected documents to understandthe temporal dimension of the implementation efforts.
All REMs are recorded on video to reconstruct statements from participants not documented during the
mapping.

Page 12 of 16

Semi‑structured interviews

Semi-structured interviews with key stakeholders (PALs,
principals, and other members of the PA committee
if necessary) will be conducted following the REMs togain a deeper understanding of the decisions, activities,
successes, and challenges within the support and delivery systems of the experimental schools. Analogous to
Stimulated Recall Interviews, which use video or audio
recordings as a starting point to stimulate reflections andconsiderations of the interviewee, the process mappingfrom the REM is intended to serve the interviewees asa memory aid and, at the same time, prevent statementsfrom being influenced by social desirability [91]. Theinterviews aim to gain a deeper understanding of what
was implemented and how the implementation of Active
School was planned and executed in both support anddelivery systems (dose of delivery). This includes identifying which interest groups were reached by the applied
strategies in the support and delivery systems, assessing
the feasibility from the perspective of these stakeholders,and determining the sustainability of the implementation
throughout the project duration. Furthermore, the investigation aims to examine the extent to which determinants such as context, provider, program characteristics,
and characteristics of the program delivery and support
systems either support or hinder the successful implementation. The interview guides are grounded in theory,drawing from implementation theory [47]. However, theinterview guidelines will be refined iteratively based on
project developments and previously collected data.
Data analysis

Due to the low risk, no Data Monitoring Committee
was formed. Data will be stored utilizing Cloud Databases, overseen by the research team. Electronic data will
be exclusively stored in the Cloud Databases, whereas
physical data will be stored securely in locked cabinets
and later transcribed electronically. The research teamregularly monitors data and performs interim analyses to check data quality. In adverse events, the relevant
information is recorded; reviews and inspections are notplanned, and access to the original documents is possible for independent auditors/inspectors and the Ethics
Commission.
Effectiveness evaluation

Data analyses will be conducted using SPSS version 28.0
(IBM Corp., Armonk, NY, USA).
The primary analysis aims to investigate whether there
is a higher level of objectively measured MVPA at thepost (12 months) and follow-up assessment (24 months)
in the experimental group compared to the waiting control group. Therefore, we will use linear mixed models

Gasser et al. BMC Pediatrics(2024) 24:561

with standard errors adjusted for clustering and MVPA
as the outcome variable. Changes in secondary outcomes(inactivity, light physical activity, step counts, aerobic fitness, coordination, self-reported physical activity, subjective wellbeing, classroom climate, school wellbeing,
and learning behavior) will be examined as secondary
analyses using the same strategy with linear mixed models. Exploration of changes in MVPA will be conductedby expanding the multilevel model to examine whether
alterations are moderated by measured individual- or
school-level characteristics. Therefore, we will examine
the potential moderating effects of individual- (physical self-concept and motivation for exercise), class- (e.g.,level, size) and school-level characteristics (physicalactivity environment in school) on student outcomes.
Additionally, we will investigate significant interaction
terms by assessing subgroup variations in the primary
outcome and selected secondary outcomes. Linear mixed
models will be utilized to examine potential mediatingprocesses, and the estimation of mediating effects will
involve the use of a cluster-bootstrapped based productof-coefficients test specifically designed for cluster RCTs.
Multiple imputation methods will be used to address
missing data. As part of our sensitivity analysis, we plan
to replicate the analysis using both an intention-to-treat
approach and a per-protocol approach. For intention-totreat analyses, we will address missing data by employing
multiple imputation methods. The per-protocol analysis
will focus solely on participants who strictly adhered tothe protocol and attended all follow-up visits. Effect sizes
will be assessed to illustrate the magnitude of differences
between the groups, and all tests will be two-sided withp-values reported accordingly. The estimates will be provided along with 95% confidence intervals.
Process evaluation

To investigate the process outcomes, quantitative datafrom the questionnaires and qualitative data, including
documents, REMs, and semi-structured interviews, areincluded. Quantitative data gathered from the questionnaires completed by principals, PALs, and teachers will
be condensed through descriptive statistics. The principal
and PAL questionnaires will depict the school context,
provider characteristics, and delivery and support systemcharacteristics. The teacher questionnaire will be used toinvestigate teacher characteristics and project-specificitems. Qualitative data, including all documents authoredby the PA committee, the REMs, and the semi-structured
interviews, will be analyzed using a framework approach[92]. We align our implementation outcomes with themodel by McKay et al. [46], while our approach to analyzing implementation determinants is based on theframework for effective implementation by Durlak et al.

Page 13 of 16[47]. Additional categories emerging during the analysis
process will be derived inductively. The MAXQDA software is used for coding all qualitative data and content
analysis [93]. This software provides comprehensive features for integrating qualitative and quantitative data to
explore causal links between process determinants andoutcomes.

Discussion
Swiss adolescents exhibit low physical activity levels [3]despite the recognized physiological and psychologicaladvantages [7, 8]. The existing empirical evidence indicates that comprehensive school-based physical activity
programs, positively impact adolescents’ physical activity
levels [28, 29]. They have the advantage that schools canadapt the promotion of physical activity to their conditions and needs, thereby contributing to greater sustainability of program’s effectiveness [19]. As such programs
currently don’t exist in Switzerland, the purpose of thisstudy is to implement and evaluate the impact of Active
School, a Swiss comprehensive school-based physicalactivity program for secondary school. However, PAL
which play a central role in the implementation of Active
School, face numerous challenges due to this comprehensive school-based approach. Therefore, the intervention of Active School consists of a specific PD training
program that aims to optimally support the PAL during
the implementation and to prepare them to overcome
the challenges, which altogether should lead to a positive impact on students’ physical activity. This study’s
strengths lie in the parallel evaluation of both the effectiveness and process and the utilization of an objective
measure of students’ physical activity as the primary
outcome. The outcomes of this study will furnish valuable insights into the implementation process and theeffectiveness of Active School. Additionally, the study will
provide new insights into how a CSPAP approach canbe applied in Switzerland to enhance physical activity
among Swiss adolescents.
Abbreviations
BMI	Body mass index
CS	Waiting control school
CSPAP	Comprehensive School Physical Activity Program
EE	Effectiveness evaluation
ES	Experimental school
ICC	Intraclass correlation coefficientIP	Implementation phase
MVPA	Moderate-to-vigorous physical activity
PA	Physical activity
PAL	Physical activity leader
PD	Professional development
PE	Process evaluation
PP	Preparation phase
RCT​	Randomized controlled trial
REM	Ripple effect mappingWHO	World Health Organization

Gasser et al. BMC Pediatrics(2024) 24:561

Acknowledgements
Not applicable.
Authors’ contributions
SV, FE, and MS conceptualized the study and secured funding for the project.
AN, MG, FE, SV, MK, and MS jointly conceptualized the intervention concept.
MG, AN, FE, SV, MK, and MS collaboratively developed the project’s evaluation
design. AN, MG, FE, SV, MK, and MS are all members of the project team. AN
and MG drafted the study protocol manuscript. All co-authors revised thework critically for important intellectual content and approved the final version of the manuscript.
Funding
Active School is funded by the Federal Office of Sport (FOSPO), Magglingen,
Switzerland [Grant Number 193008188]; the Canton of Bern (Department of
Health, Social Services and Integration (DHSSI)—Cantonal Action Programon nutrition, exercise and mental health for children, young people and theelderly (CAP); the Department of Education and Culture (DEC)—Office for
Compulsory Education and Counselling Services (OCECS) [Grant Number
2020.BKD.53056 1122431]); the Bern University of Teacher Education; theUniversity of Bern; the Berne University Research Foundation [Grant Number
41/2023_NWF]. The OCECS provides funding for the PALs financial support
over 3.5 years. The funds from the Berne University Research Foundation
were used to acquire GENEActiv devices. All institutions did not influence theconceptualization and design of the project, as described in this protocol,
and will not have any impact on its implementation, data collection, analysis,
interpretation of the results, or the decision to submit results. However, theresearch team must submit an annual progress report to the FOSPO.
Availability of data and materials
The materials used during the planned project will be made available by thecorresponding author upon reasonable request.

Declarations
Ethics approval and consent to participate
Active School has been approved by the Ethics Commission of the Facultyof Human Sciences at the University of Bern, Switzerland (Ref: 2023–03-05).
Significant modifications to the study protocol will be communicated to pertinent stakeholders. To obtain the consent of the students for the effectivenessevaluation, the research team personally informs each class about the project.
Subsequently, an information letter, including a consent form, is provided totake home. The form allows separate consent for participation in accelerometry, the aerobic fitness and coordination test, and the student questionnaire.
As the students are not of legal age, the form must be signed by the parents
and returned to the teacher within two weeks. The teacher then forwards thecompleted forms to the research team. The consent form explicitly includes
the child’s perspective in the consent statement. This ensures that bothparental consent and the child’s comprehension and willingness to participate
are acknowledged and properly documented. To treat participants’ data confidentially, each participant will be assigned an individually chosen participant
code, which will be used for data collection purposes. For the process evaluation, written consent is additionally requested from the school principals, PALs,
and teachers. This consent indicates their willingness to participate in one ormore of the following methods: questionnaires, document analysis, REM, andinterviews. All participants also have the right to withdraw from the study at
any time at their discretion.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Author details
1
Institute of Sport Science, University of Bern, Bremgartenstrasse 145,
Bern 3012, Switzerland. 2 Centre of Subject Didactics, Bern University of Teacher
Education, Fabrikstrasse 8, Bern 3012, Switzerland.

Page 14 of 16

Received: 29 March 2024 Accepted: 26 August 2024

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