SummaryThe physical education class preparatory grade students have only recreative caracter but it must contribute to increasing the effort capacity of the student The physical education class for preparatory grade students cannot have only a recreative character but it must contribute to increasing the effort capacity of the students’ body which can result into modifocations and adaptations of different organs, systems and apparatuses. Movement games are basic ways of reaching the goals of physical education at this age level (6-7 years old). Children, actively participate in accomplishing the tasks and, because of their somatic and functional particularities, they tend to reach a higher pulse rate than in standard exercises. This is what recommends a closer attention from the teacher in order to graduate effort correctly. The purpose of the present work was to apply a protocol of density in the preparatory school grade for measuring functional density and, implicitely, effort dynamics during that particular class. The hypothesis of the research was to obtain concrete and objective data about the values of cardiac frequency during effort in preparatory school students in order to be able to graduate effort in the future. The experiment took place on November 19th 2013, at "Alexandru Macedonski" Gymnasium School in Craiova at the preparatory school grade A, teacher M.G. The density protocol was applied by the students in their 3rd year study, The Faculty of Letters - Pedagogy Primary and Preparatory School Level, Craiova. The interpretation of the density protocol was about measuring motric, pedagogical and functional density, the values of the cardiac rate by sketching the effort dynamics. All data was given to the teacher, to be rightly informed, and to be able to graduate effort correctly for the children, in the future.