The objectives were two: a) to examine the impact of active breaks (AB) on the physical activity (PA) of year-2 students during their lessons, recess, and after school, and b) to analyze possible PA compensatory declines during the day. 46 schoolchildren (28 girls) aged between 7-8 years participated. A quasi[1]experimental design was carried out with pretest and posttest measurements. The experimental group (n=22) received an AB program developed by the teachers and students. PA was recorded using accelerometers. The repeated measures ANOVAs found significant effects on moderate and vigorous PA (MVPA) and very vigorous PA in favor of the experimental group. The increase was 71’23”/week (14’17”/day) of MVPA and 10’03”/week (2’01”/day) of very vigorous PA. In the experimental group, there was a decrease (6’54”/week) in MVPA during their recess. Nevertheless, the sedentary activity time during classes was reduced by 73’30”/week. In conclusion, involving both teachers and students in the designing of AB can be an effective way to increase student PA.