level of physical activity and screen time among iranian children and adolescents at the national and provincial level: the caspian-iv study

background: there are few epidemiological reports on adherence to physical activity (pa) and screen-time (st) recommendations among iranian children and adolescents at the provincial level. we used nationally representative data to provide recent prevalence estimates of iranian children who met the recommendations for pa and st.   methods: this nationwide study was conducted among 14,880 students aged 6-18 years from 30 provinces of iran. the frequency of the recommended level for pa (>1 hours/week) and st (<2 hours/day) and different combinations of pa and st was determined in the studied population.   results: in this study, 13,486 students (response rate: 90.6%) were studied. overall, 18.62%, 34.11%, 50.66% and 9.63% of the students reported high st, low level of pa, high tv watching and high computer working, respectively. the frequency of the recommended level of pa and st was 53.92%. of the studied population, 6.63% had low pa and high st. paradox combinations of low pa and low st and moderate/high pa and high st was prevalent among 27.47% and 6.26% of the children and adolescents. the lowest and highest frequency of recommended level of pa and st was 38.9% and 65%, respectively. the lowest and highest frequency of low pa and high st was 1.87% and 13.77%, respectively.   conclusion: the results of this study revealed that the frequency of low pa was high and that approximately 46% of the students did not meet the recommended level of pa and st. the findings indicated that preparing facilities for improving pa level among children should be the main priority in our future interventions in this field.