Most pediatric populations do not meet the physical activity (PA) recommendations set by international organizations. The effectiveness of casual PA advice provided during medical consultations has not been adequately assessed for its role in fostering this healthy habit. This study aims to evaluate the effectiveness of medical prescriptions for PA in increasing PA levels in children compared to standard health advice (HA), as well as measuring the effectiveness of these recommendations in reducing daily screen time (ST) in the pediatric population. A randomized controlled clinical trial with parallel groups was conducted, including 130 participants aged 6 to 14 years. Data on PA levels (duration and intensity), ST, and anthropometric measures were collected via questionnaire. Participants were divided into two groups: HA (3 minutes) and medical prescription of exercise [MPE] (10 minutes). PA levels were assessed at 3 and 12 months, with results recorded using the same questionnaire. A multivariate data analysis was performed. Further research is needed to develop effective and sustainable public health interventions to prevent long-term sedentary behavior in children.

• Both HA and MPE interventions could effectively increase children's PA duration and intensity, resulting in a higher PA classification range.
• An inverse relationship may be identified between ST and PA, suggesting that reducing ST could encourage healthier habits in children.
• Pediatricians play a pivotal role in promoting lifestyle changes through brief yet targeted interventions, significantly influencing children's PA levels and reducing ST. These findings highlight the need for further research to optimize public health initiatives within pediatric care.

Inclusion Criteria:

We included pediatric patients between 6 and 14 years of age who were part of two pediatric PC groups of an urban health centre in Granada (Spain) who attended a face-to-face consultation of any type.

Exclusion Criteria:

chronic or complex pathology preventing moderate or intense physical activity or those who did not give consent

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restrictive block randomization conducted using STATA version 16 software. Those within the intervention group received an individualized MPE, while participants in the control group received brief HA. To avoid classification bias in terms of PA level measurement, both the randomly selected intervention (HA and MPE) and the subsequent data collection (baseline, at 3 months and 12 months) were performed by the same blinded investigator, ensuring data consistency and validity. Participants did not know which intervention they were receiving as they did not know the actual recomendations in pediatric patients about exercise and screen time