An interventional study of Green Prescription (Teacher-Led) and Green Prescription (Interdisciplinary) in Social Support, Screen Time and Physical Inactivity, sponsored by Poznan University of Physical Education. Completed at 1 site in Poland. Open to participants aged 15 Years to 17 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-18.
Sponsored by Poznan University of Physical Education · Not applicable, Interventional, and Prevention
This study evaluated the effectiveness of the Green Prescription, a school-based behavioral intervention that incorporated health education, designed to increase physical activity among adolescents aged 15-17 years who were insufficiently active.
Participants received individualized written physical activity recommendations together with motivational support to encourage gradual increases in leisure-time physical activity. The intervention was tailored to three target groups: adolescents with overweight or obesity, excessive screen time, or low perceived social support.
The study consisted of two sequential cohorts. In the first cohort, the Green Prescription was delivered by a physical education teacher. In the second cohort, the intervention was delivered by a physical education teacher supported by an interdisciplinary team consisting of a dietitian, psychologist, special education teacher, and physiotherapist.
Physical activity and other health-related outcomes were assessed at baseline, immediately after the 12-week intervention, and six months later.
The study evaluated the effectiveness of the Green Prescription in each intervention group and determined whether the interdisciplinary delivery model resulted in greater improvements in physical activity and healthy lifestyle behaviors than the teacher-led model.
Regular physical activity during adolescence contributes to physical, mental, and social well-being. Despite well-established health benefits, many adolescents do not achieve recommended levels of physical activity. Schools provide an important setting for implementing behavioral interventions that encourage lifelong healthy habits.
The Green Prescription was a school-based behavioral intervention that incorporated health education to promote leisure-time physical activity among adolescents with insufficient physical activity. The intervention combined individualized written physical activity recommendations with health education and regular motivational support. Activity goals were tailored to each participant and were progressively increased throughout the intervention.
The study consisted of two sequential cohorts. Participants with insufficient physical activity were assigned to one of three intervention groups according to their primary risk factor: overweight or obesity, excessive screen time, or low perceived social support. Each intervention group followed the same Green Prescription framework while receiving recommendations and educational materials tailored to its primary risk factor. Adolescents with sufficient physical activity served as a comparison group and did not receive the intervention.
In the first cohort, the Green Prescription was delivered by a physical education teacher. In the second cohort, the intervention was delivered by a physical education teacher supported by an interdisciplinary team consisting of a dietitian, psychologist, special education teacher, and physiotherapist. Each cohort included three parallel intervention groups and one comparison group, allowing evaluation of both the effectiveness of the Green Prescription within each target group and the added value of the interdisciplinary delivery model.
Outcomes were assessed at baseline, immediately after the 12-week intervention, and six months after completion of the intervention. The study evaluated both the immediate and sustained effects of the Green Prescription on physical activity and related health outcomes.
General inclusion criteria
Intervention Groups (A-C)
Participants were eligible if they met all of the following criteria:
- Insufficient physical activity, defined as reporting fewer than 5 days during the previous week with at least 60 minutes of moderate-to-vigorous physical activity, assessed using the MVPA questionnaire.
and met one of the following group-specific criteria:
Group A - Overweight or Obesity
Comparison Group (Group D)
Exclusion Criteria
Adolescents with insufficient physical activity and overweight or obesity participated in the first study cohort. Participants received the Green Prescription delivered by a physical education teacher. The intervention included individualized physical activity recommendations, motivational support, and educational materials focused on increasing physical activity and improving weight-related health behaviors.
Behavioral: Green Prescription (Teacher-Led)
Adolescents with insufficient physical activity and excessive screen time participated in the first study cohort. Participants received the Green Prescription delivered by a physical education teacher. The intervention included individualized physical activity recommendations, motivational support, and educational materials focused on increasing physical activity and reducing recreational screen time.
Behavioral: Green Prescription (Teacher-Led)
Adolescents with insufficient physical activity and low perceived social support participated in the first study cohort. Participants received the Green Prescription delivered by a physical education teacher. The intervention included individualized physical activity recommendations, motivational support, and educational materials focused on increasing physical activity and strengthening social support for active lifestyles.
Behavioral: Green Prescription (Teacher-Led)
Adolescents with sufficient physical activity participated in the first study cohort. Participants completed the same assessments as the intervention groups but did not receive the Green Prescription intervention.
Adolescents with insufficient physical activity and overweight or obesity participated in the second study cohort. Participants received the Green Prescription delivered by a physical education teacher with support from an interdisciplinary team consisting of a dietitian, psychologist, special education teacher, and physiotherapist. The intervention included individualized physical activity recommendations, motivational support, and educational materials focused on increasing physical activity and improving weight-related health behaviors.
Behavioral: Green Prescription (Interdisciplinary)
Adolescents with insufficient physical activity and excessive screen time participated in the second study cohort. Participants received the Green Prescription delivered by a physical education teacher with support from an interdisciplinary team consisting of a dietitian, psychologist, special education teacher, and physiotherapist. The intervention included individualized physical activity recommendations, motivational support, and educational materials focused on increasing physical activity and reducing recreational screen time.
Behavioral: Green Prescription (Interdisciplinary)
Adolescents with insufficient physical activity and low perceived social support participated in the second study cohort. Participants received the Green Prescription delivered by a physical education teacher with support from an interdisciplinary team consisting of a dietitian, psychologist, special education teacher, and physiotherapist. The intervention included individualized physical activity recommendations, motivational support, and educational materials focused on increasing physical activity and strengthening social support for active lifestyles.
Behavioral: Green Prescription (Interdisciplinary)
Adolescents with sufficient physical activity participated in the second study cohort. Participants completed the same assessments as the intervention groups but did not receive the Green Prescription intervention.
The Green Prescription is a school-based behavioral intervention incorporating health education to promote leisure-time physical activity among adolescents with insufficient physical activity. The intervention includes individualized weekly written physical activity recommendations, educational materials, and weekly motivational support, supplemented by additional support when required, delivered by a physical education teacher over a 12-week period. All participants follow the same Green Prescription framework, with group-specific objectives, physical activity recommendations, and educational materials tailored to their primary risk profile (overweight or obesity, excessive recreational screen time, or low perceived social support). Activities were adapted to group needs and recommended PA levels. Written recommendations and educational materials were delivered electronically.
The Green Prescription is a school-based behavioral intervention incorporating health education to promote leisure-time physical activity among adolescents with insufficient physical activity. The intervention includes individualized weekly written physical activity recommendations, educational materials, and weekly motivational support, supplemented by additional support when required, over a 12-week period. The intervention is delivered by a physical education teacher together with an interdisciplinary team consisting of a dietitian, psychologist, special education teacher, and physiotherapist. All participants follow the same Green Prescription framework, with group-specific objectives, physical activity recommendations, and educational materials tailored to their primary risk profile (overweight or obesity, excessive screen time, or low perceived social support). Written recommendations and educational materials were delivered electronically.
Change in Moderate-to-Vigorous Physical Activity (MVPA) Screening Score
Self-reported physical activity was assessed using the MVPA screening measure. Participants reported the number of days on which they engaged in at least 60 minutes of moderate-to-vigorous physical activity (1) during the previous week (P1) and (2) during a typical week (P2). The MVPA screening score was calculated as the mean of the two responses: (P1 + P2) / 2, with a possible range of 0-7 days. Higher scores indicate a greater number of days with at least 60 minutes of MVPA.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Mean Daily Step Count (Huawei Watch Fit SE)
Objective physical activity assessed using Huawei Watch Fit SE. Participants wore the device for a 7-day baseline monitoring period, continuously throughout the 12-week intervention, for a 7-day post-intervention monitoring period, and for a 7-day monitoring period at the 6-month follow-up. The primary outcome is the mean daily step count derived from the monitoring periods used for outcome assessment.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Body Mass Index (BMI)
Body Mass Index (BMI) was calculated from measured body weight and height as weight in kilograms divided by height in meters squared (kg/m²). Weight and height were combined to derive a single reported BMI value; the reported unit of measure was kg/m².
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Waist Circumference
Waist circumference was measured in centimetres (cm) and reported as a single waist circumference value in cm at each assessment point.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Hip Circumference
Hip circumference measured in centimetres (cm).
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Body Fat Percentage
Body fat percentage (FatP) assessed using Tanita bioelectrical impedance analysis.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Fat Mass
Fat mass (FatM) measured using Tanita bioelectrical impedance analysis.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Fat-Free Mass
Fat-free mass (FFM) measured using Tanita bioelectrical impedance analysis.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Total Body Water
Total body water (TBW) assessed using Tanita bioelectrical impedance analysis.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Predicted Muscle Mass
Predicted muscle mass (PMM) measured using Tanita bioelectrical impedance analysis.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Screen Time
Screen time was assessed using selected items from the Health Behaviour in School-aged Children (HBSC) questionnaire and average daily active screen time recorded from participants' smartphones.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Sleep Duration
Sleep duration assessed using Huawei Watch Fit SE. The outcome is the mean total sleep duration derived from 7-day monitoring periods.
Time frame: Baseline (7-day monitoring period), immediately after the 12-week intervention (7-day monitoring period), and 6 months after completion of the intervention (7-day monitoring period).
Change in Perceived Social Support
Perceived Social Support assessed using the Short Scale of Youth's Social Support Assessment (SSYSS). Total scores range from 1.0 to 4.0, with higher scores indicating higher perceived support.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Change in Health-Related Quality of Life
Health-related quality of life assessed using the KIDSCREEN-52 questionnaire. Total scores range from 23.3 to 100.0, with higher scores indicating better health-related quality of life.
Time frame: Baseline, immediately after the 12-week intervention, and 6 months after completion of the intervention.
Plan to share: No — Individual participant data (IPD) will not be shared because the study involved minors, and no data-sharing plan was included in the study protocol or participant consent procedures.
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Poznan University of Physical Education