A number of factors may limit the ability of a joint to move through a full, unrestricted range of motion. The bony structure may restrict the endpoint in the range. An elbow that has been fractured through the joint may deposit excess caldum in the joint space, causing the joint to lose its ability to fully extend. However, in many instances bony prominences stop movements at normal endpoints in the range.
Excessive fat may also limit the ability to move through a full range of motion. An athlete who has a large amount of fat on the abdomen may have severely restricted trunk flexion when asked to bend forward and touch the toes. The fat may act as a wedge between two lever arms, restricting movement wherever it is found. Skin might also be responsible for limiting movement. For example, an athlete who has had some type of injury or surgery involving a tearing incision or laceration of the skin, particularly over a joint, will have inelastic scar tissue formed at that site. This scar tissue is incapable of stretching with joint movement. Muscles and their tendons, along with their surrounding fascial sheaths, are most often responsible for Limiting range of motion. When performing stretching exercises for the purpose of improving flexibility about a particular joint, one is attempting to take advantage of the highly elastic properties of a muscle. Over time it is possible to increase the elasticity, or the length that a given muscle can be stretched. Athletes who have a good deal of movement at a particular joint tend to have highly elastic and flexible muscles. Connective tissue surrounding the joints, such as ligaments on the joint capsule, may be subject to contractions. Ligaments and joint capsules do have some elasticity; however, if a joint is immobilized for a period of time, these structures tend to lose some elasticity and shorten. This condition is most commonly seen after surgical repair of an unstable joint, but it can also result from long periods of inactivity.
It is also possible for an athlete to have relatively slack ligaments and joint capsules. These individuals are generally referred to as being loose - jointed. Examples of this would be an elbow or knee that hyperextends beyond 180 degrees Frequently there is instability associated with loose - jointedness that may present as great a problem in movement as ligamentous or capsular contractures.
Skin contractures caused by scarring, ligaments, joint capsules, and musculotendinous units are each capable of improving elasticity to varying degrees through stretching over lime. With the exception of bony structure, age, and gender, all the other factors that limit flexibility may be altered to increase range of joint motion.
