Conditioning of cartilage during normal activities is an important factor in the development of osteoarthritis.

Mechanical factors have long been implicated in the aetiology of osteoarthritis (OA). The two most popular hypotheses regarding the mechanism of cartilage damage are: the application of too high a stress and the mechanism of fatigue. Mechanical failure in any material, however, can be caused by either or both of these mechanisms. It is hypothesized that, because cartilage is a living tissue, the threshold at which it fails by either mechanism is regulated by the prevalent stresses arising in a joint. As these stresses are determined by activities and lifestyles, a low failure threshold can be the result of prolonged periods of low-level activity, which, if interrupted with short periods of intense activities, can subject weakened cartilage to damaging stresses. Were this hypothesis proven, it would address difficulties encountered with these hypotheses and explain some clinical observations. It would also have implications for the activities and lifestyles of individuals.