Adaptations of Cartilage to Anaerobic Training

The following is an exclusive excerpt from the book  Essentials of Strength Training and Conditioning-4th Edition With Web Resource, published by Human Kinetics. All text and images provided by Human Kinetics.

Cartilage is a dense connective tissue capable of withstanding considerable force without damage to its structure. The main functions of cartilage are to:

• provide a smooth joint articulating surface,
• act as a shock absorber for forces directed through the joint, and
• aid in the attachment of connective tissue to the skeleton.

A feature unique to cartilage is that it lacks its own blood supply and must depend on diffusion of oxygen and nutrients from synovial fluid (which is why cartilage does not easily repair itself following injury). Two primary types of cartilage are significant in relation to physical activity. Hyaline cartilage (articular cartilage) is found on the articulating surfaces of bones. Fibrous cartilage is a very tough form of cartilage found in the intervertebral disks of the spine and at the junctions where tendons attach to bone.

The fact that articular cartilage gets its nutrient supply via diffusion from synovial fluid provides a link for joint mobility to joint health. Movement about a joint creates changes in pressure in the joint capsule that drive nutrients from the synovial fluid toward the articular cartilage of the joint (180). Immobilization of a joint prevents proper diffusion of oxygen and essential nutrients throughout the joint. This results in the death of the healthy cells within cartilage, called chondrocytes, and a resorption of the cartilage matrix (195). Current understanding indicates that human cartilage undergoes atrophy, or thinning, when external loading is removed (e.g., postoperative immobilization and paraplegia). However, the effect that increased external loading has on average cartilage thickness remains to be fully elucidated (46). In any case, it is likely that genetic contribution plays a greater role in determining cartilage morphology.