Recognized side effects on health associated with sports participation in youth include overtraining, doping, and exposure to harassment and violence. Many of these effects originate in contexts where young athletes are beginning to make decisions about their sports practices on their own. This study sets out to explore knowledge and reasoning about health among adolescent athletes and to describe how health knowledge management structures are associated with different social systems. Qualitative data were collected from focus groups involving 65 young Swedish athletes aged 16-17years. The participants knowledge and reasoning about health were examined using a deductive thematic analysis, categories from Blooms taxonomy of educational objectives, and Luhmanns social systems theory. The meaning of health was found to have a dynamic character for the young athletes, associated with constantly striving to satisfy immediate needs and fulfill short-time life goals. The athletes thinking about health was associated with a pragmatic health-as-a-resource perspective, characterized by group self-comparisons, rapid cognitive processing, and opportunistic substitutions. They expressed a particular interest in experiential learning and personally relevant procedural knowledge, and they perceived that their factual knowledge about health was saturated. The results of this study add emphasis to the importance of involving adolescent sportspersons in the development of health education programs and contextualizing the programs to the athletes specific age and social environment.