Recreational exercise has achieved great popularity. Possible benefits to participants include increased longevity, decreased risk of cardiovascular disease, improved psychological well-being, and greater fitness. An important but yet unanswered concern is whether exercise or physical overuse conditions play a role in the pathogenesis of OA. In humans, anecdotal observations have suggested relationships between recreational activities and degenerative joint disease. The few controlled studies that exist, however, reported have indicated that exercise need not be deleterious to joints. Available data may be interpreted to suggest that reasonable recreational exercise--carried out within limits of comfort, putting joints through normal motions, and without underlying joint abnormality--need not inevitably lead to joint injury, even over many years. Finally, we are witnessing thoughtful re-evaluation of physical exercise as a therapeutic modality for arthritis patients. It is possible that certain patients may achieve psychological and clinical benefit from selected exercise programs.