Background: Movement is key in physical education, but the educational value of moving is sometimes obscure. In Sweden, recent school reforms have endeavoured to introduce social constructionist concepts of knowledge and learning into physical education, where the movement capabilities of students are in focus. However, this means introducing a host of new and untested concepts to the physical education teacher community. Purpose: The purpose of this article is to explore how Swedish physical education teachers reason about helping their students develop movement capability. Participants, setting and research design: The data are taken from a research project conducted in eight Swedish secondary schools called "Physical education and health--a subject for learning?" in which students and teachers were interviewed and physical education lessons were videorecorded. This article draws on data from interviews with the eight participating teachers, five men and three women. The teachers were interviewed partly using a stimulated recall technique where the teachers were asked to comment on video clips from physical education lessons where they themselves act as teachers. Data analysis: A discourse analysis was conducted with a particular focus on the ensemble of more or less regulated, deliberate and finalised ways of doing things that characterise the eight teachers' approach to helping the students develop their movement capabilities. Findings: The interviews indicate that an "activation discourse" ("trying out" and "being active") dominates the teachers' ways of reasoning about their task (a focal discourse). When the teachers were specifically asked about how they can help the students improve their movement capacities, a "sport discourse" (a referential discourse) was expressed. This discourse, which is based on the standards of excellence of different sports, conditions what the teachers see as (im)possible to do due to time limitations and a wish not to criticise the students publicly. The mandated holistic "social constructionist discourse" about knowledge and learning becomes obscure (an intruder discourse) in the sense that the teachers interpret it from the point of view of a dualist discourse, where "knowledge" (theory) and "skill" (practice) are divided. Conclusions: Physical education teachers recoil from the task of developing the students' movement capabilities due to certain conditions of impossibility related to the discursive terrain they are moving in. The teachers see as their primary objective the promotion of physical activity--now and in the future; they conceptualise movement capability in such a way that emphasising the latter would jeopardise their possibilities of realising the primary objective. Should the aim be to reinforce the social constructionist national curriculum, where capability to move is suggested to be an attempt at formulating a concept of knowledge that includes both propositional and procedural aspects and which is not based on the standards of excellence of either sport techniques or motor ability, then teachers will need support to interpret the national curriculum from a social constructionist perspective. Further, alternative standards of excellence as well as a vocabulary for articulating these will have to be developed.