Introduction: Mobility, play and physical activity in childhood and early childhood will play a decisive role in the mental and physical health of individuals. So we intend in this study Investigating the amount of physical activity and its effect on the physical composition and mental health of elementary school students in Nahavand city.

Material & Methods: The research is a descriptive survey, the statistical population included all male students aged 12 to 15 studying in the primary education level of Nahavand city, using the cluster sampling method and 50 people as a statistical sample. considered. The mental health evaluation questionnaires of children and adolescents aged 6 to 14 years (1984) and the questionnaire of international physical activities of children and adolescents were used. In order to analyze the data, Pearson and Spearman correlation coefficients were used.

Results: Statistically, high physical activity had a significant (inverse and negative) relationship with mental and physical health components (weight, body mass index, hip-to-hip ratio, body mass) P<0.05. Also, average physical activity only had a significant relationship (inverse and negative) with changes in body mass, P<0.05. In the third group (low physical activity), the level of activity had no significant relationship with any of the studied changes.

Conclusion: Based on this research, it seems that with the increase of physical activity in students, which is done in the form of daily games, a combination of physical improvement and the level of their mental health increases.