The study protocol of the ePro-Schools project: an eHealth program for promoting physical activity and healthy nutrition in schools

Abstract

Background

Early adolescence is key for adopting healthier lifestyles, yet disadvantaged communities often lack resources to support these changes, perpetuating health inequities. Schools play a crucial role in promoting physical activity and healthy eating. eHealth solutions, like online platforms, offer scalable, cost-effective ways to deliver interventions. These platforms can also enhance adolescent engagement and help bridge health resource gaps. The ePro-Schools project aims to co-design and test an eHealth platform to promote healthy habits among adolescents in socially disadvantaged settings.

Methods

A randomized controlled trial (RCT) will be carried out with the participation of 6 secondary schools (three controls and three intervention), with a sample size estimated at 1000 students of Central Catalonia (Spain). In the intervention schools, focus groups sessions and meetings with stakeholders have been conducted to co-create the ePro-Schools eHealth platform. Students and school staff are pilot testing the platform to assess the platform’s usability, functionality, and layout. Finally, the RCT will be conducted, in which the intervention group will have full access to the ePro-Schools platform (an interactive and informative platform), while the control group will only have access to the informative platform with health literacy content on physical activity, nutrition, and healthy habits. In both groups, adolescents will complete validated questionnaires at baseline, post-intervention, and at the six-month follow-up to assess their physical activity and eating habits, including depressive symptoms, quality of life, social isolation, and mental health. Sociodemographic characteristics will also be collected. Implementation, effectiveness, and cost-effectiveness analysis will be performed.

Discussion

The ePro-Schools project introduces a co-designed eHealth platform that integrates physical activity and healthy eating promotion within schools. The intervention aims to enhance adoption, relevance, and sustainability across diverse settings. ePro-Schools project could reduce health inequalities, improve adolescents’ physical and mental well-being, and strengthen daily health habits. The model’s scalability and embedded implementation planning may support long-term integration into school systems, informing future policies and contributing to educational engagement, reduced disease risk, and broader population health impact.

Trial registration

This trial is registered in ClinicalTrials.gov, with the registration number NCT06792461.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-026-27587-8.

Background

The early years of adolescence (11–13 years) are a fundamental period for adopting and maintaining healthier lifestyles, such as higher levels of physical activity and a healthy diet, as these behaviours continue into young adulthood (19–24 years) and adulthood [1–3]. Programs that promote healthier lifestyles are particularly important for adolescents from socially disadvantaged backgrounds (e.g., neighbourhood, family education level, family income.), as they are more likely to engage in unhealthy lifestyle behaviours such as low physical activity, excessive sedentary activities, and unhealthy eating habits, and consequently experience poorer physical and mental health than their peers from higher socioeconomic backgrounds [4–6]. The World Health Organization (WHO) defines this systematic difference in health outcomes as health inequity [7].

Adolescents from socially disadvantaged settings do not receive the necessary support and access to programs to reduce health inequity. Meaning that they do not have access to high-level educational, social and health services, which reinforces healthy inequities [8, 9]. Programs focusing on the promotion of physical activity and healthy eating for adolescents are essential to reducing healthy inequity in socially disadvantaged populations since higher physical activity levels and healthier dietary patterns are linked to better physical and mental health outcomes during adolescence and adulthood [1–3]. However, there is limited high-quality information on the determinants of physical activity and dietary habits focusing on adolescents from socially disadvantaged settings, which is surely contributing to the low number of available effective programs for this population. Currently, most of the studies are focused on high-income population groups [1–3].

The best-available evidence underscores the central role of schools in implementing programs that promote healthy lifestyles in adolescents from socially disadvantaged settings, highlighting the importance of promoting physical activity and healthy eating [1–3, 10–14]. Furthermore, WHO and UNESCO launched the initiative: Making Every School a Health Promoting School [15], which emphasises the role of schools in addressing health inequity. Particularly, most adolescents, even in socially disadvantaged areas, attend schools [16]. Therefore, successful programs have a high potential to reach the vast majority of adolescents from socially deprived settings [1–3, 10–14].

eHealth solutions, such as online platforms, may facilitate the implementation of interventions conducted in school settings with lower socioeconomic status (students and family included). Particularly, allowing easy and continuous delivery of the intervention content throughout the school year instead of relying on a few in-person encounters/workshops [17, 18]. Compared to interventions solely delivered in person, eHealth platforms have greater scalability and may eventually reduce the costs thanks to potential large-scale implementation [19]. Furthermore, eHealth platforms have greater adaptability capacity since updates in the intervention can be launched by updating the algorithm of the platform whereas in-person interventions demand considerable time from revision and update before implementation [9, 20]. eHealth solutions, especially in the school setting, might diminish the gap in access to health and educational resources caused by social inequalities [21], since Internet access is becoming universal, especially in the European Union (EU).

Previous interventions aimed at improving physical activity and dietary habits among adolescents in socially disadvantaged settings have often achieved only small to moderate impacts (d < 0.40) and have struggled to engage students effectively, limiting their potential effectiveness [1–3]. The ePro-Schools study will address these limitations by analysing high-quality cohorts to assess the determinants of physical activity and dietary habits in this population, which will be used to enhance the intervention program and implementation strategies. Building on successful existing programs and incorporating the latest scientific evidence, the ePro-Schools intervention further employs a co-creation process, actively involving students and teachers from the intervention schools. This approach aims to enhance the relevance and acceptability of the intervention, increase user engagement, and thereby amplify its impact on physical activity and dietary habits in adolescents from socially disadvantaged settings. Additionally, the ePro-Schools intervention will be delivered through a scalable digital platform, which may enable a consistent delivery of intervention content throughout the school year and may facilitate the implementation of interventions in school-settings. Given all the above, we hypothesise that adolescents from socially disadvantaged settings with access to the ePro-Schools program will improve their physical activity and dietary habits [1–3].

Study objectives

The main aim of the ePro-schools project is to co-design and test the effectiveness of an eHealth platform for promoting physical activity and dietary habits among adolescents from socially disadvantaged settings. Secondary outcomes of the trial include physical fitness, subjective health and the psychological, mental and social well-being, teachers and classmate support, social isolation and quality of life.

Methods

Design

The trial is registered at Clinical Trials Registry ClinicalTrials.gov (NCT06792461) and the design, conduct and reporting will adhere to the Consolidated Standards of Reporting Trials [22] and Template for Intervention Description and Replication [23] checklists. ePro-Schools is a two-arm parallel group pragmatic cluster randomised controlled trial (RCT) with an intervention and a wait-list control groups.

Sample size

A minimum of 1,000 adolescents will be necessary to provide a statistical power higher than 80% to detect moderate differences (d = 0.50) in changes in physical activity levels, time in sedentary behaviour, and dietary habits compared with the control group after the intervention. This calculation considered two measurements, an aggregated intra-class correlation of schools of 0.20, α = 0.05, and 20% refusal to participate and loss to follow-up. A total of 1,000 adolescents will also allow us to stratify the effectiveness analysis by key characteristic, such as sex at birth (male, female) or socioeconomic status.

School recruitment and selection

The RCT will be conducted in the area of Central Catalonia (Spain), particularly in secondary schools from socially disadvantaged settings. To identify secondary schools from socially disadvantaged settings, we used a sociodemographic score previously developed and applied in the DESKCohort study [24]. This score considered factors such as family income, educational levels, crime rates and school dropout rates. Schools in the lowest 20% of this score were eligible and invited to participate.

Eligible schools were invited during the 2024/25 school year. Initially, six schools accepted to participate and were cluster- randomly assigned to either the intervention or control group by an external statistician using a computer-based random number generator. One school withdrew its consent to participate for reasons external to the project and another school was excluded for lack of engagement with the research team over the preparatory months. Two additional schools were therefore invited as replacements and were randomized using the same procedure.

During the school year 2024/25, the research team have been in contact with school directors and physical education teachers to involve them in the planning of the implementation of the ePro-Schools RCT that will start in the 2025/26 school year – beginning in September. Originally, we planned to enroll participants (adolescents and school staff) in September and October 2025 and to conduct the baseline assessments during that period. However, due to major challenges during enrollment (e.g., low response rates and limited engagement), enrollment will now be completed in January, with baseline assessments conducted immediately afterward. Post-intervention assessments will occur during May and June 2026 and follow-up assessments during February and March 2027.

Figure 1 shows the recruitment and randomization process of the participating schools.

Fig. 1.

Flow diagram of recruitment, randomisation and participation in the ePro-Schools project

Participants

The main study population will be adolescents attending secondary schools from socially disadvantaged settings in the region of Central Catalonia. All students enrolled in the 1 st, 2nd and 3rd grades of participating schools will be invited to participate, independently of the biological sex, gender or ethnicity.

In addition, physical education teachers, tutors and school directors from the selected secondary schools will be invited to participate in the study.

The ePro-Schools intervention program

The intervention Program was developed by an interdisciplinary team of researchers and practitioners from physical activity, nutrition, psychology, and information and communication technology backgrounds, including medical informatics. All the content will be presented in Catalan.

Intervention development followed an iterative, multi-method approach combining top-down (theory- and evidence-based) and bottom-up (co-creation-based) strategies. The top-down process integrated Social and Emotional Learning interventions (SEL), Self-Determination Theory (SDT), the Supportive, Active, Autonomous, Fair, Enjoyable (SAAFE) principles and Cognitive-behavioural Therapy strategies (CBT) as theoretical frameworks and pre-existing intervention materials to design the first version of the program. The bottom-up process consisted of co-creation procedures aimed at validating and revising this initial draft that included qualitative focus group studies and pilot testing with adolescents and school staff. In addition, meetings with school staff and policymakers’ representatives were scheduled to collect their feedback for the preparation and implementation of the program. In summary, during the co-creation activities, teachers and students were presented with a preliminary version of the intervention content and provided feedback about their perceptions regarding acceptability, feasibility, appropriateness as well as potential barriers for implementation [19]. This feedback was considered during the development phase of the intervention program. The following papers will describe the intervention development and co-creation procedures. This subsection of the current manuscript will focus on the description of the intervention program.

The ePro-Schools intervention program follows a multi-level approach that provides user-specific content for adolescents, families, PE teachers, and school staff, with the primary aim of improving adolescents’ health-related habits. Within this framework, two main components serve as the central channels for delivering the intervention:

1. Intervention platform: A password-protected eHealth platform (eSano), offering interactive training modules for adolescents and school staff

2. Information platform: An open-access psychoeducational website, available in three tailored versions for adolescents, teachers and school staff, and families. It serves as the central access point to the program, providing general information, guidance on available resources, and access to the interactive modules on the intervention platform.

The ePro-Schools intervention platform

The intervention platform is delivered through the eSano eHealth platform, a modular, secure, and scalable system developed for the implementation of internet- and mobile-based interventions. The platform enables the creation, customization, and delivery of interactive training modules through a web-based content management system (CMS), an interface for professionals providing support (so-called eCoaches), and a mobile- and browser-accessible app for participants. It offers features such as multimedia content, interactive exercises, and self-monitoring tools. Designed with consideration of data protection and medical device regulations, the platform provides a flexible infrastructure for digital health research and practice. In the ePro-Schools project, participants can access the intervention platform via the web browser since local representatives from the educational and health departments were reluctant that a project was implemented via a dedicated mobile app [25] since the Catalan government is implementing a strict ban policy for mobile phones in the schools. More detailed information about the eSano platform can be found elsewhere [26, 27].

Students and school staff in the intervention group will have access to the intervention platform as soon as baseline assessments are finalized. The content of the intervention platform consists of topic-specific modules with the goal of promoting physical activity and healthy nutrition. Modules include text-based psychoeducation, interactive elements such as quizzes, case examples, and self-assessments, as well as optional “homework” tasks. To further enhance engagement and support comprehension, these components are complemented by professionally produced multimedia content (e.g., audio, avatars, images, downloadable material).

See Additional File 1 for a general overview of the eSano modules and for an example of the contents of a specific module.

Modules in the intervention platform for adolescents

Table 1 below presents the platform modules intended for adolescents.

Table 1.

Overview of e-Pro Schools programme content for students in the intervention platform

Module Title	Goals	Main Points
Feel good every day: simple life hacks	Promote overall well-being with small lifestyle changes	Tips to eat better, move more, and rest well Fun and easy strategies for daily health habits
Fuel up: what smart eating really looks like	Teach students how food affects their energy, mood and performance	Link between diet and well-being Easy healthy eating habits Empower students to choose better
Small Steps, Big Changes!	Encourage gradual behaviour changes toward healthy eating	Practical tips and simple recipes Make first steps easy and achievable
The Secret Power of Your Drinks!	Show how beverage choices impact energy and well-being	Why it’s important to know what you're drinking Drinks that energize vs. drinks that slow you down How to choose healthier options to feel your best
Fresh & Tasty: Eat what’s in season!	Teach the benefits of eating seasonal fruits and vegetables	Why seasonal foods are fresher, tastier, and more nutritious Economic and environmental benefits of seasonal eating Find out what’s in season right now
Build your best plate: master the healthy food pyramid!	Help students build balanced meals using the food pyramid	What the food pyramid is and how it works How to create a healthy, balanced plate Practical tips for making smart food choices every day
Power up your mornings!	Show how a healthy breakfast can improve your day	The importance of breakfast for energy, focus, and mood What makes a breakfast nutritious and delicious Simple ideas to start the day right
Benefits of Physical Activity	To introduce the clinical recommendations for physical activity, its health benefits, and various types of exercises students can engage in	- What is physical activity? - WHO recommendations - Physical and mental health benefits - My daily routine: easy ways to stay active
Understanding Fitness	To understand what being "fit" means, explore the main fitness components, and learn how to build a balanced fitness routine	- What does being fit mean? - Fitness components: cardio, strength, flexibility, etc.—How to improve fitness - Creating a balanced routine
Growth Mindset for Physical Activity	To understand how mindset affects participation in PE and challenges. Learn how to embrace mistakes and persist through difficulties	- What is a growth mindset? - Sports & mindset: inspiring stories - Real examples from adolescents - Strategies and tips to develop a growth mindset - “Not yet” approach
SMART Goals – Defining Your PA Goal	To guide students in creating a personalized, SMART physical activity goal for the term	- Introduction to SMART goals - Step-by-step guidance: specific, measurable, achievable, relevant, time-bound - Examples from peers - Staying motivated over time
Create Your Own Physical Activity Plan	To design a personal training plan based on goals and preferences, focusing on frequency, intensity, and types of activities	- What do I want to train? - Workout structure: warm-up, main activity, cool-down - Designing a session that fits my goals
What Is My Ideal Activity?	To help students identify the types of physical activities that suit them best, using an interactive tool and local resources	- Types of activities: individual, group, outdoor, indoor - What’s available near me? - Search tool and connection with local facilities - Decision tree: choosing your ideal activities
Training Sessions for This Afternoon: Get Your Workout	To offer ready-made workouts students can use right away by choosing from different activity options	- Workout session builder - Choose from different intensities and types - Mix and match warm-ups, main workouts, and cool-downs

Modules in the intervention platform for school staff

Table 2 describes the modules that were primarily designed for PE teachers, but that school staff (e.g., directors, administrators, other teachers) will also be able to login in the intervention platform. In summary, the intervention contents offered for teachers were focused on enhancing the quality of the PE lessons based on the SAAFE principles.

Table 2.

Overview of e-Pro Schools programme content for school staff in the intervention platform

Module Title	Goals	Main Points
Introduction to ePro-Schools	Introduce the project’s purpose, relevance, and the teacher’s role. Ensure teachers understand the objectives and how they’ll be supported	• Overview of the project's aims and expected impact • Health challenges and opportunities in adolescence - • he importance of PE lessons and teacher involvement • Project components and planned activities
Introduction to SAAFE Principles	Familiarize teachers with the SAAFE framework and encourage its implementation in PE lessons	• What is SAAFE? (Supportive, Active, Autonomous, Fair, Enjoyable) • Research evidence behind SAAFE • Rationale and importance of each principle • Tips and examples for applying each principle
Step by Step – Create Your SAAFE Lesson	Equip teachers with a structured approach to designing lessons aligned with SAAFE principles	• Planning, delivering, and evaluating PE lessons • Defining lesson goals (SMART format) • Applying SAAFE principles in practice • Structuring the lesson for flow and engagement • Practical checklist for planning
How to Motivate and Engage Students	Understand key motivational drivers in adolescents and learn strategies to increase participation	• What motivates adolescents? • Intrinsic vs. extrinsic motivation • The role of autonomy, mastery, and relatedness • Designing fun, varied, and relevant activities • Addressing common motivational barriers
How to Optimize Your PE Lessons	Learn how to maximize active time and minimize inefficiencies in PE lessons	• Why efficient PE lessons matter • Common time-wasters and how to avoid them • Smart planning of warm-ups, transitions, and equipment use • Strategies for lesson flow and structure • Quick checklist for active, engaging sessions
Supporting Students’ Confidence (Growth Mindset)	Learn how to build students’ confidence and promote inclusive participation through a growth mindset	• Understanding fixed vs. growth mindset in PE • Boosting student confidence through small wins and peer support • Encouraging participation across ability levels • Adapting activities for mixed abilities • Inclusive practices for a safe and enjoyable PE experience
Fostering Great Communication	Develop communication strategies to build a positive, supportive, and trusting classroom environment	• Why teacher communication matters • Using positive, specific feedback • Role of non-verbal communication (tone, body language) • Building trust and emotional safety • Managing difficult conversations constructively

The ePro-Schools information platform

The ePro-Schools project includes a digital information website designed to support adolescents, families, teachers, and schools in promoting physical activity and healthy eating habits. Accessible to participants in both intervention and control groups, the website serves as an open-access entry point to the ePro-Schools program. The platform aims to provide clear, user-friendly health literacy resources with tailored content for each stakeholder group. It offers practical, evidence-informed information to facilitate the promotion of physical activity and healthy nutrition within school communities. Content is organized by user group, thematic area (physical activity and healthy nutrition), and key topics to ensure ease of navigation and relevance for end users. Although the information website does not include the interactive features of the intervention platform, it is designed to remain engaging and accessible, incorporating info boxes, dropdown menus, images, and visual figures to enhance user experience. Additional sections provide project updates, news, and maps of local resources.

Table 3 summarizes the topics and content areas presented on the ePro-Schools information platform for adolescents, families, teachers, and schools.

Table 3.

Overview of e-Pro Schools programme content for students in the control group

User group	Thematic area	Main pages	Examples of covered topics
Adolescents	Physical activity	About physical activity; Exercises to become fit; Active living	Benefits of physical activity, recommended activity levels, fitness, fun activities, screen time use
	Nutrition	Understanding nutrition; How to eat healthy; SMART eating	Healthy eating plate, seasonal foods, Mediterranian diet and food pyramid, healthy breakfast
Families	Physical activity	About physical activity; Supporting students' physical activity; Active living	Family as physical activity promoters, barriers and recommendations, fun activities
	Nutrition	Understanding nutrition; How to eat healthy?; SMART eating	Building healthy family habits, healthy breakfast, foods to limit
Schools and teachers	Physical activity	Importance in PA promotion; Supportive practices; Beyond PE classroom, SAAFE principles; Benefits of PA	PE in social-emotional development, classroom strategies, lifelong habits, equipment and spaces, family involvement, policy recommendations
	Nutrition	Building a healthy food culture; Foundations of healthy eating; Safety first, role of nutrition in student well-being; Supporting healthy eating in schools	School canteen, nutrition education, food hygiene, student well-being, practical ways to support healthy habits
All users	General	Newsblog; About us; Around you	Project updates, involved partners, map of local resources

Intervention group

Adolescents, families, and school staff in the intervention group will have access to the ePro-Schools platform, which includes both the intervention and information platforms, during the 2026 school year via a web browser once baseline assessments are completed. A designated support person will be available to provide technical assistance to users throughout the trial, via email.

None of the intervention components are mandatory or required to be completed. Therefore, all users can freely choose which parts of the intervention program to follow, explore or engage with. This flexible approach was designed to respect the diverse needs and contexts of users and schools, and to allow them to engage with the content most relevant and useful to their specific circumstances and interests, acknowledging that some schools may already have their own strategies to promote physical activity or nutrition.

Control group

During the 2026 school year, participants in the control group will have access to the information platform. During the 2026/27 school year, the control group will also gain access to the intervention platform (Waiting list control group).

Intervention implementation strategies

A number of strategies are planned to support the implementation of the intervention program. In the beginning of the 2025/26 school year (September 2025), the research team met with school’s directors and administrative board and physical education teachers to define the strategies that should be implemented at school level in promoting physical activity and healthy nutrition. Based on these mettings, the research team will present a list of potential activities; hence school staff can choose which ones they would like a more detailed plan for implementation during the school year. Those activities could be a tournament to take place at the school, a day dedicated to healthy foods, etc. In addition, we plan to have periodic meetings, every 4/6 weeks, with PE teachers to support them in implementing the classes and introducing the concepts of the ePro-School program to students. Furthermore, we will also carry-out meetings with nurses from the local health department who provide support to the intervention schools to evaluate the possibility of them acting as promoters of the projects among school staff, students and families. In addition to the strategies to implement at school level, we can also send communication materials about the intervention directly to users via email to promote usage of the platform.

Outcomes and assessments

Data will be collected using a self-administered questionnaire through REDCap (Research Electronic Data Capture), a secure web app that complies with the GDPR security standards [28]. Adolescents enrolled in the trial will answer the ePro-Schools assessment battery at baseline (Feb 2026), post-intervention (May-Jun 2026) and at follow-up (Feb-Mar 2027).

Primary outcomes

Physical activity and sedentary behaviours

Physical activity will be assessed by the International Physical Activity Questionnaires Short Form (IPAQ-SF [29] and the Physical Activity Questionnaire for Adolescents (PAQ-A) [30]). The IPAQ-SF provides estimates of physical activity in MET-minutes/week, with higher values indicating higher activity levels, and allows classification into low, moderate, or high activity. The PAQ-A yields a mean score ranging from 1 to 5, with higher scores reflecting higher physical activity. Both questionnaires provide extensive information about the domains of physical activity as well as context-specific information about physical activity and sedentary behaviour. Combined, both questionnaires include 20 items.

Dietary habits

Dietary habits will be assessed with the PREDIMED questionnaire [31]. It is based on Mediterranean Diet items regarding healthy eating habits, and it is composed of 14 items. For the current study, the question regarding wine consumption will be deleted. The PREDIMED score will be calculated as follows: < 9 points (classified as low adherence) and > 9 (classified as high adherence). The higher the score, the healthier the adolescent food habits are.

Secondary outcomes

A series of secondary outcomes will be assessed to examine potential additional effects of the intervention, as well as variables that may mediate the relationship between the intervention and the primary outcomes (see Table 4).

Table 4.

List of secondary outcomes

Variables	Questionnaire	Additional information
Physical fitness	EUROFIT fitness test [46]. Teachers already perform this testing with students. It assesses six dimensions of fitness, but we will request information on the: Léger test, standing broad jump, 30 m sprint and shuttle run	PE teachers will assess students’ fitness levels through the following dimensions: cardiorespiratory endurance, strength (standing broad jump), speed (30 m sprint), running speed—agility (shuttle run: 10 × 5 m)
Subjective health and psychological, mental and social well-being	Kidscreen-10 [47]	KIDSCREEN-10 [47] has 10 items and measures general health-related quality of life (HRQoL) for adolescents. Each item on the KIDSCREEN-10 is rated on a 5-point Likert scale, reflecting the frequency or intensity of the feelings or behaviours described. The scores for the 10 items are summed to produce a total score between 10 and 50 points, where the higher the score, the higher the HRQoL. The total score can then be transformed into a T-score or percentile rank, based on normative data, to facilitate interpretation. In addition, KIDSCREEN-10 includes a general health question to provide an overview of the adolescent’s overall wellbeing
Depressive symptoms	Center for Epidemiological Studies Depression (CES-D) [48]	CES-D [48] is a 20-item questionnaire that measures depressive symptomatology in adolescents and adults in the general population. Each item on the CES-D is rated on a 4-point Likert scale, indicating the frequency of symptoms experienced during the past week (ranging from “rarely or none of the time” to “most or all of the time”). The scores for the 20 items are summed to produce a total score between 0 and 60 points, where a higher score indicates a greater presence of depressive symptoms. A commonly used cutoff score of 16 or higher suggests clinically relevant levels of depressive symptoms. The CES-D can be used for screening purposes and for assessing changes in depressive symptoms over time in both research and clinical settings
Teachers and Classmate Support	Teachers and Classmate Support Scale [49]	The Teachers and Classmate Support Scale is a measure designed to assess the perceived support that students receive from their teachers and classmates. It consists of two subscales: Teacher Support and Classmate Support. All items have a five-point Likert scale. For each subscale, the scores for the individual items (1 to 5) are summed to obtain a total score (3–15). Higher scores indicate higher perceived support from teachers or classmates
Social isolation	Social Isolation Questionnaire [50]	The Social isolation questionnaire is composed of 17 items that can be categorised into three domains: feelings of loneliness, friendships, and family support. The score can assume values from 0 to 117, with lower scores indicating lower levels of social isolation
Quality of life	Child Health Utility 9D Index [51]	CHU9D has 9 items and measures health-related quality of life (HRQoL) in children and adolescents, with a focus on utility-based outcomes suitable for economic evaluations. Each item on the CHU9D represents a distinct domain of daily life (e.g., worry, pain, tiredness, schoolwork) and is rated on a 5-point scale, reflecting the severity or impact of each issue on the individual’s life on that day. Responses are converted into a single utility score ranging from 0 (equivalent to being dead) to 1 (perfect health), based on a validated scoring algorithm derived from general population preferences. This utility score can be used to calculate quality-adjusted life years (QALYs) for use in health economic analyses
Sleep Quality	Pittsburgh Sleep Quality Index (PSQI) Questionnaire	It is a self-reported questionnaire with 19 questions grouped into 10 items. In scoring the PSQI, seven component scores are derived, each scored 0 (no difficulty) to 3 (severe difficulty). The component scores are summed to produce a global score (range 0 to 21)
Water consumption		Participants will be asked how many glasses of water they drink per day
Binge drinking		They will be asked about how many days they have been drunk during the last 30 days, and how often they drink alcohol (never, once or less per month, between 2–4 times per month, 2–3 times per week, 4 times o more per week)

Other assessments

Students will also be inquired about sociodemographic information to characterize the sample as well for potential adjustments for analysis or to be included in the analysis as potential moderators. In the ePro-Schools assessment battery we will inquire about birthdate, sex, gender, country, town/city, neighbourhood, high school, place of birth, educational level of the parents, perception of economic status, academic level, money available for personal expenses, pathologies in the last 12 months and use of screens [24].

Technical data on intervention uptake (students and teachers)

Another outcome of the study is the uptake of the intervention. For the intervention platform, this includes basic usage data on how often and how participants have used the platform (e.g., number of modules completed, which modules were completed). For the information website, this usage data is comprised of the number and sequence of user visits and the point of access (i.e., the region). This information is essential to evaluate the interactions between usage and effectiveness and to assess the effectiveness of the various modules.

Qualitative interviews

Interviews (1 × 1) and/or focus groups (up to 10 participants) will be conducted with volunteers from all stakeholder groups (adolescents, school staff and families), after the post-intervention questionnaire. These interviews/focus groups will primarily focus on inquiring users in terms of impact, usability, acceptability, appropriateness, feasibility, barriers, and facilitators for implementation.

Statistical analyses

Descriptive analyses will be performed to summarize the sociodemographic variables and scales. Frequencies and percentages will be used for categorical variables, and means, standard deviations (SD), medians, and interquartile ranges (IQR), minimum and maximum for continuous variables. To evaluate baseline differences between the intervention and control groups the Chi-squared test or t-test will be applied.

Effectiveness analysis

The effectiveness evaluation will be conducted based on improvements in physical activity level and dietary habits. Specifically, the primary analysis of effectiveness will be reflected in an increase in physical activity level (total time in physical activity and higher moderate-to-vigorous physical activity), reduction in sedentary behaviour and improvement in dietary habits. In addition, effectiveness will be assessed through improvements in the secondary outcomes, as specified in a preceding section.

A linear mixed-effects model (LMM) will be used to assess the effectiveness of the intervention on continuous outcomes measured across baseline and post-intervention assessment points and a Generalized Estimating Equations (GEE) will be used for categorical outcomes. Adolescents will be nested within schools. A complementary analysis will include all the three time points to evaluate the potential intervention effects at follow-up.

The model will include fixed effects for time, group (intervention vs. control), and their interaction (group × time), which captured the differential change over time attributable to the intervention. The interaction term will be the main parameter of interest for assessing intervention effectiveness. To account for the multilevel design, the model will include a random intercept for each participant to account for repeated measures, and a random intercept for each school to adjust for within-school clustering. Other covariates associated with the outcome may be included in the model as fixed effects, depending on the objective. All models will be adjusted for the sex and age of the student.

The effectiveness analyses will be carried out following the intention to treat principle (ITT). In addition, a complete-case analysis will be conducted as a sensitivity analysis to assess the robustness of the findings. Differences between included and excluded participants will be examined to explore potential bias due to missing data.

Moderator analysis

We will also evaluate whether the intervention effects vary according to certain characteristics such as participants’ sex, socioeconomic status, and physical activity level/nutrition habits at baseline. These analyses will involve testing for statistically significant interaction effects between the intervention and potential moderators within linear mixed models.

Mediation analysis

Mediation analysis will be performed using structural equation modelling (SEM) to assess whether the effect of the intervention on the primary outcome is mediated by one or more intermediate variables (mediators) such as the secondary outcomes or other variables or whether changes in physical activity/nutrition habits mediate the potential effect on health parameters.

All available data will be included under the assumption that data are missing at random (MAR), All statistical tests will be two-sided, and a p-value ≤ 0.05 will be considered indicative of statistical significance. Effect estimates will be reported with corresponding 95% confidence intervals (95%CIs) to indicate the precision of the estimates. The analysis will be done with SAS (version 9.4) and/or R software.

Cost-effectiveness analysis

The economic evaluation will be conducted as a cost-effectiveness analysis. Incremental cost-effectiveness ratios (ICERs) will be estimated using the Child Health Utility 9D index, which measures health-related quality of life. The Child Health Utility 9D will serve as the primary outcome for the cost-effectiveness analysis and may be supplemented by additional mental health and well-being measures, as outlined in the primary and secondary outcomes.

Implementation evaluation

Implementation outcomes will be investigated as perceived acceptability, appropriateness, feasibility of the intervention program among students and school staff assessed during the qualitative interviews at post-intervention. In addition, adoption of the ePro-Schools program will be measured as the uptake of the intervention and the number of strategies implemented at school level. For the intervention platform, the uptake includes basic usage data on how often and how participants have used the platform (e.g., number of modules completed, which modules were completed). For the information website, this usage data is comprised of the number and sequence of user visits and the point of access (i.e., the region). Adoption will be measured throughout the RCT-study period.

Ethics considerations

This study has been elaborated in strict compliance with the ethical principles of the Nuremberg Code (1946), Declaration of Helsinki (1964) and Good Clinical Practice. All data collected for this study will be treated according to the Regulation 2016/679 of the European Parliament and of the Council of April 27, 2016, regarding the protection of natural persons (RGPD) and Organic Law 3/2018, of December 5, on the Protection of Personal Data and Guarantee of Digital Rights (LOPD-GDD). The study was approved by the IDIAP Jordi Gol clinical research ethics committee with registration code 24/099-P.

Participant data will be coded to maintain privacy, with access restricted to authorized personnel. Written consent will be obtained from both adolescents and their parents or legal guardians, as well as teachers. Personal data will be stored securely in encrypted, password-protected files, and shared only when legally required or with authorized researchers. Data will be pseudonymized for internal use, and anonymized data will be shared with non-EU collaborators. The data will be stored for 5 years for study integrity and potential future research. Anonymized data will be kept in a repository for future use. All participants will be informed of their voluntary participation and the right to withdraw at any time.

Discussion

Physical activity and healthy nutrition are key elements in promoting physical and mental health [32–34]. Despite increasing efforts to promote adolescent health, many existing interventions remain limited in scope, effectiveness, and sustainability [35]. The ePro-Schools project was developed to address these gaps by co-designing and evaluating an eHealth platform that integrates evidence-based strategies to promote physical activity and healthy eating within the school context, with the broader aim of supporting adolescents’ mental well-being.

Compared to previous school-based initiatives, ePro-Schools introduces several innovations to enhance the project’s effectiveness. A co-creation process to ensure cultural and contextual fit, an adaptable, modular structure for feasibility and scalability; the integration of evidence-based interventions in digital but also in-person activities; and a dedicated focus on implementation strategies with leadership engagement to support a comprehensive, sustainable approach to promote adolescents’ health.

First, ePro-Schools adopts a co-creation approach with students, teachers, school staff and policy makers to ensure cultural and contextual fit, directly addressing a common limitation in earlier initiatives. Previous programs often lacked contextual fit and scalability, particularly in disadvantaged settings, and few were co-designed with key stakeholders or structured to promote sustained engagement through school integration [35, 36]. Using qualitative research and focus groups, ePro-Schools actively incorporates the real needs and lived experiences of its target users. This participatory method aims to enhance engagement, increase adoption rates, improve cultural relevance, and ensure the feasibility of long-term implementation. By involving adolescents in the project’s design and providing resources that match their interests and needs, the program empowers them to take charge of their own health.

Secondly, the project builds on previous findings that digital tools can be effective in supporting healthy behaviours [37], especially when delivered through accessible platforms and aligned with school infrastructure. Delivering the intervention via a web-based platform helps overcome common barriers in low-resource contexts, such as financial constraints, geographic isolation, and limited access to recreational or nutritional resources [9, 21, 38]. While concerns exist about adolescent screen time, using the internet to deliver trustworthy health information and skills training can turn a potential barrier into a health promotion opportunity,especially when paired with guidance on responsible digital use. Through this accessible, engaging, and culturally tailored eHealth platform, ePro-Schools addresses structural and contextual barriers that often limit the impact of traditional school-based health promotion programs.

Third, the program’s adaptable, modular design is a key component intended to enhance feasibility and scalability across diverse school contexts. Rather than imposing a rigid curriculum, the platform allows families, teachers, and adolescents to select topics most relevant to their goals and circumstances. To further improve efficacy, the digital platform incorporates evidence-based behavioural techniques such as goal-setting, immediate feedback, and self-monitoring [39, 40]. By combining these digital elements with in-person activities, ePro-Schools delivers a hybrid model that integrates seamlessly into daily school routines while minimizing staff burden.

Finally, ePro-Schools integrates implementation planning from the earliest stages of the design. This includes a dedicated implementation package with in-person activities and structured meetings with school principals to identify potential barriers and facilitators to adoption. Embedding these discussions early ensures that the intervention is shaped not only by health promotion goals but also by practical considerations for school integration. Previous studies have noted that many digital health interventions fail to achieve lasting impact due to limited attention to adoption, fidelity, and sustainability [41, 42]. The ePro-Schools hybrid model addresses this gap by aligning digital content with daily school routines and co-designing in-person activities with teachers and students, thereby fostering regular platform use and supporting the program’s integration as a sustainable component of school practice.

From a public health perspective, promoting physical activity and reducing sedentary behaviour during adolescence is crucial both for the prevention of future cardiometabolic diseases and for the promotion of mental health and well-being during this critical developmental period. (1). The ePro-Schools project addresses these challenges through a combined focus on physical activity and healthy nutrition. By fostering healthier daily habits, the program has the potential to reduce health inequalities and reduce risks of depression, anxiety and social isolation, improving overall student’s physical and mental health [33, 43]. Together, these improvements could translate into long-term reductions in medical costs but also enhance educational engagement and academic performance of adolescents [44, 45]. These combined benefits make a strong case for investing in policies that integrate scalable, evidence-based eHealth programs into school systems.

Despite its strengths, the project is expected to face several anticipated challenges. First, recruiting schools and obtaining consent from minors and parents may pose difficulties. However, the project benefits from established collaboration with over 80% of schools in the region through a previous initiative, and direct engagement with school personnel is planned to help overcome this barrier. Second, integrating the intervention into school routines presents logistical challenges. Multicomponent programs require careful coordination to ensure fidelity and minimize disruption. To mitigate this, teachers, school leadership, and health services are actively involved in the co-design and implementation planning. Additionally, targeted dissemination and implementation strategies are planned to enhance engagement across all stakeholder groups. To support sustainability, regular monitoring meetings with participating schools will be held to track progress, identify emerging barriers, and co-develop practical solutions. This iterative feedback process is expected to strengthen the long-term integration of the intervention into school settings.

Authors’ contributions

Conceptualization: RL, JMH, AE, RP, JW, JP, CAS, GS, IG, RK, CV, KK, JVA; Data curation (DESKcohort): AE; Formal analysis (DESKcohort): AE; Funding acquisition: RL, JVA, RP, JW, GS, CAS, IG; Methodology: RL, RP, JW, JP, CAS, GS, IG, RK, CV, KK, MP, JS, JMH, JVA, Project administration: RL, Software: RP, RK, CV, MS, KK; Resources: EM, CAS, GM, RP, RK, CV, Supervision: RL; Visualization: MMM, EM, MG, JVA; Writing-original draft: MMM, EM, RL, MP; Writing – review & editing: EM, MG, MMM, AE, RL, RP, JW, JP, CAS, GS, IG, RK, CV, MS, KK, MP, JS, JMH, GM, RES, MBP, AAM, LE, MMS, GCB, JVA.

Funding

This project received funding from Instituto de Salud Carlos III (ISC-III) under the umbrella of the Partnership Fostering a European Research Area for Health (ERA4Health) (GA N° 101095426 of the EU Horizon Europe Research and Innovation Programme).

The study will be conducted with the support of the Department of Health of the Government of Catalonia, through the 2024 grant call under the Strategic Plan for Research and Innovation in Health (PERIS 2022–2027), in the category of Research Projects focused on primary care, with file code SLT035/24/000054. In addition to the Miguel Servet fellowship (grant CP19/00183) funded by Acción Estratégica de Salud – Instituto de Salud Carlos III, co-funded by European Social Fund “Investing in your future”.

Data availability

The Catalan Institute of Health is responsible and guarantees the protection of the storage, preservation and processing of the data, ensuring its confidentiality. The data will be stored in the Research Support Unit of the Catalan Institute of Health of Central Catalonia. In the event of data petitions by an external research team, data obtained as part of this project will be made available to external investigators to this proposal through a formal Data Transfer Agreement (DTA). In no case will explicit identifiers (e.g. contact information, medical record numbers) be included in analytic files for either internal use or sharing with external collaborators.

Declarations

Ethics approval and consent to participate

The study was approved by the IDIAP Jordi Gol clinical research ethics committee with registration code 24/099-P.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.