The present study aims to establish the relationship between subjective perception of effort with the objective measurement of effort through accelerometer; as well as to contrast the perception of physical effort that schoolchildren have of their Physical Education classes and that of teachers who teach them. Seven monitored Physical Education classes were monitored, where they participated 56 (21 school children, 35 girls) between 9 and 12 years of age (M = 11.2 DS=0.72), and 5 teachers (age M =33.2 SD=4.26). We used the "Scale of measurement of perceived exertion (EPInfant)" validated for the Chilean school population; while for the objective measurement of the effort it was considered the level of physical activity through accelerometer, measured through devices Bioharness, Zephyr T. The students expressed a perception of less effort (M=3.4=1.49) in relation to their Physical Education Teachers (M=4.6=0.50) was statistically significant differences, whereas the correlation analysis between levels of physical activity and perception of effort resulted in that there is a weak but statistically significant correlation (r=0,338, p=0.011) between both variables. These results continue the trend evidenced in the few studies that have addressed this issue, and it is estimated that the perception of effort has potential as an evaluation tool; however it is necessary to reaffirm the evidence of its usefulness in Physical Education classes.
