Abstract
In brief: Despite 15 years of research on exercise compliance, supervised exercise programs typically have dropout rates of 50%. Researchers have used entry profiles and theories from behavioral psychology in efforts to predict and prevent dropout, with limited success. A possible key to the puzzle is that, contrary to a common assumption, exercise may be a unique health behavior, not subject to precisely the same prompts and reinforcements as other health habits. Other problems with past research include imprecise terminology, unstandardized measures, and a failure to adjust methods to suit specific populations and circumstances. Needed for a better understanding of exercise compliance are new definitions, new methods, and broader perspectives.