[The effects of exercise on articular cartilage]

The effect of exercise on articular cartilage has been assessed on animal models and on humans using various imaging techniques. Joint cartilage, whose water content decreases itself thanks to its unique permeable medium, maintains load distribution and joint function together with the synovial fluid under physiologic conditions and sports activities. The adaptive capacity of joint cartilage is limited under various conditions such as excessive load bearing or prolonged immobilization; however, when these factors are reversed deformed cartilage returns to its former state under normal conditions. Due to its adverse effect on joint cartilage, immobilization period following cartilage damage or operation should be as short as possible for wound healing. It is reported that exercise contributes to cartilage healing and reduces risk for injury, and that moderate exercise can even decrease the number of cases requiring arthroplasty. Conversely, excessive (harsh) exercise may be associated with increased cartilage damage or degenerative changes. Despite the presence of osteophytic changes in joint cartilage of athletes performing mild sports activities, these may not result in osteoarthritis due to the adaptive feature of joint cartilage. In contrast, the risk for osteoarthritis is increased in professional sportsmen exposed to acute repetitive impact and torsional loading. This article reviews the influence of controlled, passive-active exercise on healing, and on the development of osteoarthritis and the short- and long-term changes in articular cartilage associated with exercise and participation in sports of different duration and intensity.