Results
A total of 24 elementary schools with 2095 children were screened for eligibility. After excluding 63 children who were unable to participate on 2 or more school days, were unsuitable for physical activity, or refused to provide informed consent, 2032 children (1040 girls [51.2%] and 992 boys (48.8%) with a mean (SD) age of 9.22 [0.62] years) were included and randomized to the intervention group (12 schools with 1012 children) or the control group (12 schools with 1020 children). Of these children, 1903 (93.7%) completed the follow-up visit and 129 (6.3%) were lost to follow-up due to school transfer or leave of absence (