In the rapidly changing society of the late nineteenth century, American medical theory and practice functioned as a social force to shape and limit the ways in which females viewed their physical potential. This paper analyzes the social and physical expectations which were elaborated for and experienced by middleclass urban females throughout their life span, identifies the kinds of exercise prescriptions which were promoted by doctors to assist women in fulfilling these expectations at different life stages and points out the underlying significance of these prescriptions in defining and perpetuating notions of females' limited physical capabilities. For late nineteenth century women, two significant influences upon their body behavior were: the physical realities of sickness and early death which modified, or curtailed female energy and physical capacity; and the discursive practices of medical experts and scientists concerning the identification and etiology of female ill-health and disease and their agreed upon therapies for assisting women to maintain, or regain their health. An understanding of the disease model which informed medical prescriptions for exercise explains, in part, why physicians concentrated their efforts upon women's reproductive capacity and lifestyle habits rather than upon the widespread and devastating diseases that look such a toll upon women before the turn of the twentieth century.