Flexibility programs are planned, deliberate, and regularly performed sets of exercises designed to progressively increase the range of motion of a joint or series of joints. Flexibility is an important component of health-related physical fitness but one that is often neglected even though it requires a minimal investment in time, effort, and equipment.

Factors that limit joint movement include (1) the bony structure of the joints (the skeleton is established by heredity, but it can be harmed by trauma, disease, calcium deposits, etc.); (2) the amount of tissue (muscle and fat) around and adjacent to the joint; (3) the elasticity of muscles, tendons, and connective tissue; and (4) the skin (scar tissue from surgery or a laceration over a joint may limit movement). Other factors that influence flexibility are age, gender, and level and type of physical activity. Young people are more flexible than adults because tendons lose their elasticity with age. However, inactivity may play a greater role than the aging process in the loss of flexibility because muscles and other soft tissues lose elasticity when not used. Active individuals are usually more flexible than inactive people. Women tend to be more flexible than men because the hormones that permit women’s tissue to stretch during the childbirth process facilitate all body stretching. The range of motion for most movements begins to decline in the mid-20s for men and women. (Complete Assessment Activities 5-1 through 5-4 at the end of this chapter to determine your flexibility.)

Joint flexibility is important for several reasons. Inflexible muscles around the joints limit range of movement, eventually inhibiting activities of daily life. This phenomenon is most frequently seen in older people who have difficulty reaching down to tie their shoes or bending over to get a drink of water from a fountain. Lack of flexibility in the shoulders can affect performance of normal duties, such as changing an overhead light bulb or removing a can of vegetables from a cupboard. Tight muscles may also contribute to joint deterioration by subjecting the bones to excessive pressure, causing pain and abnormalities in joint lubrication. Regular flexibility exercises can improve body posture. Flexibility exercises following aerobic activity reduce muscle soreness.

According to the American College of Sports Medicine (ACSM), stretching exercises may prevent injuries. The supporting data come primarily from observational studies, which are not as definitive as randomized, controlled clinical trials. But, even though scientific evidence does not strongly support flexibility training for injury prevention, sports medicine specialists advocate its use. Based upon the available evidence as well as experience, flexibility exercises help to maintain a full range of joint motion.

Maintenance of flexibility is most important for the prevention of lower-back pain. For example, a sedentary lifestyle characterized by sitting for long periods leads to a loss of flexibility and increases the likelihood of lower-back injury. Flexibility of the hamstring muscles (a group of muscles in the back of the thighs) and the lower-back muscles contributes to good posture. Posture is also improved by the development of strong abdominal muscles and the maintenance of normal body weight. Extra body weight, particularly that which accumulates around the abdominal area, throws the body out of balance and applies a forward force on the lower (lumbar) spinal area, which places extra stress on the lower back.

The benefits of flexibility training are summarized in Just the Facts: Benefits of Flexibility Training. See also Nurturing Your Spirituality: The Ancient Arts of Tai Chi and Yoga.