The Green Prescription Program for Increasing Physical Activity in Adolescents

Effectiveness of the Green Prescription: The Preventive Role of Health Education

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.

General inclusion criteria

• Adolescents aged 15-17 years.
• Enrollment in a participating secondary school.
• Health status allowing participation in physical activity.
• Stable body weight during the month preceding enrollment (±1 kg).
• Written informed consent from the participant and a parent or legal guardian, as required by local regulations.

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

• Body fat percentage above the age- and sex-specific reference values.
• BMI ≥25 kg/m² (used as an auxiliary screening criterion). Group B - High Screen Time
• Recreational screen time ≥4 hours per day. Group C - Low Social Support
• Low perceived social support assessed using the Student Social Support Scale for Young People (SSYSS).
• Low psychological well-being assessed using the KIDSCREEN-52 questionnaire (boys <37.29; girls <42.64).

Comparison Group (Group D)

• Sufficient physical activity, defined as reporting at least 5 days during the previous week with at least 60 minutes of moderate-to-vigorous physical activity, assessed using the MVPA questionnaire.
• No participation in the Green Prescription intervention.

Exclusion Criteria

• Secondary obesity.
• Acute or chronic medical conditions preventing participation in physical activity.
• Pregnancy or breastfeeding.
• Current psychological or psychiatric diagnosis requiring active treatment.
• Failure to provide written informed consent.