This paper presents selected findings from a wider study on the expression of health within physical education (PE) curricula in secondary schools in England and Wales. The study revealed that the expression of health in PE broadly reflected ideologies associated with promoting "fitness for life" and "fitness for performance" and that representations of both discourses were present, to a lesser or greater extent, in all schools in the study. Curiously, however, rhetorical "fitness for life" discourses were commonly expressed through "fitness for performance" practices in the form of testing and training activities. This paper attempts to explain this mismatch between health-related policy and practice by focusing on what was revealed about the influences on the expression of health in PE. A case study approach was adopted, involving five state secondary schools, three in England and two in Wales. Data sources included health-related school documentation, interviews with PE teachers and observation of a health-related unit of work in one of the schools. The reasons that testing and training activities were the most common contexts for the delivery of health-related learning included the following: conceptual confusion and limited understanding, leading to a belief that training and testing activities are unproblematic and result in increased health, activity and fitness levels; the resolution of pragmatic issues associated with large groups, limited space and minimal equipment as well as preparation for accredited courses in PE; tradition and a desire by teachers to remain with familiar content and teaching approaches, and limited awareness of alternative "fitness for life" pedagogies. This study has served to increase awareness of the influences on and tensions between health-related discourses in secondary school PE curricula in England and Wales and has provided further demonstration of and insight into the complex relationship between health-related policy and practice.