Despite growing numbers of references to Vygotsky’s historical-cultural framework in the international literature, the interventionist principles of his methodology and relationship to practice remain implicit or absent in the literature. The objective of this article is to present a framework for intervention and research rooted in Vygotsky’s framework and one that mobilizes cross self-confrontations. This Vygotskian methodology is part of an intervention in response to a request from a regional taekwondo league, following a change in the application of fighting rules. This article demonstrates how this methodology enables the development of techniques and the analysis of development processes simultaneously. The results illustrate the advancement of athletes’ techniques through the progressive instrumentalization of biomechanical data. The Vygotskian methodology empowers athletes to assume an active role in the analysis of their techniques, thereby facilitating their development. In other words, the principle mobilized here is not to describe technique qualitatively, but to bring about qualitative changes. This is achieved by developing the athlete’s activity through the use of biomechanics as a means of deliberation, comparison, controversy, astonishment, dialog and reworking techniques.