Three types of dense fibrous connective tissue are described: articular cartilage; tendon; and ligament; and the characteristics of each are related to its function. Articular cartilage is the smooth covering over the surface of bone at joints, and is comprised of up to 80 percent water. This smooth covering serves to decrease the friction between the surfaces in synovial joints, and it serves as a cushioning and shock absorbing surface in the joints of the lower limb. Overuse activities and the aging process will cause damage to articular cartilage, producing pain, loss of joint mobility, and eventual damage to bone. Tendons and ligaments are similar in structure, being comprised primarily of collagen fibers arranged in parallel bundles. These collagen fibers are embedded in a fluid matrix, along with chonrocytes and proteoglycan molecules. Overuse activities and the aging process will cause inflammation and weakness of the collagen bundles, resulting in strain injuries or chronic inflammation. Strenuous training programs which include eccentric exercise and deceleration activities may strengthen ligaments and tendons and prevent injuries. (Author/JD)