The fitness industry is now a globally popular enterprise. In addition, there are several visible governmental campaigns to improve physical activity levels in Europe, North America as well Australia and New Zealand. With these developments, the interest in studying exercise as social, cultural, and political issue has also increased. In this chapter, I propose first to map how sociological research on fitness and exercise has evolved, theoretically and methodologically, since the early 1990s. Acknowledging the multiplicity of approaches, I then highlight how critical theory, particularly, has advanced how we know about and practice fitness. Finally, I compare and contrast the impact of critical research with poststructuralist research to assess how different knowledges might produce social change through exercise and fitness.