This study, rooted in physical and sport education, contemplates the body development process of high school students who have started a learning sequence of step practising, within the framework of the CP5 – own competence n° 5. Starting from a holistic approach of the body, which is simultaneously living, experienced and described, the porosity between those three dimensions is deciphered for six high school students. The exploration paths of this thesis are articulated around an epistemological rooting in emersiology, where crossed scientific observations offer an opportunity at tackling the student’s body experience, so as to set up new educational and professional paths for the student to be aware of his/her own body. Several access paths, with self-confronting over a background of audiovisual traces in the first and third persons, and measuring the heart beatings via a cardio frequency-meter, contribute to defining the high school student’s capacity body. The nature of the knowledge built upand updated in the course of the classes speaks in favor of the sensitive perception’s acuity, as a complement to an intense practicing whose aim is to improve the aerobics capabilities. The different results illustrate the way in which the high school student’s esthesiological repertory increases his/her interoceptive cartography, by activation and sensitive awakening, while displaying as a consequence the building up of perceptive know-hows. By questioning two differentiating teaching paths through how his/her effort is felt, the high school students’ esthesiological and sensitive heterogeneity is revealed. While making it possible to singularly assess the living body’s capabilities through the high school student’s aerobics performance in step, these research works incite teachers to co-build an attentive listening attitude towards their bodies by the students, so that their trust in what they experiment is better and favorable to the development of their persons.