Elasticity of the muscles, tendons, and ligaments allows not only for controlled quick movements, but for avoidance of muscle pulls. Manual stretching exercises can increase the stretch tolerance of muscles and connective tissue, adapting them for the demands of sport. Flexibility refers to the ability of soft tissue to relax and yield to stretch forces. Flexibility exercises are designed to increase range of motion or to maintain normal range of motion. Flexibility can be limited by bone structure or by soft tissues such as the muscles and their fascial sheaths, the joint capsule, or the tendons.
Soft tissue stretching can bring about significant changes in joint mobility.
Besides being an important part of conditioning for sports participation, flexibility exercises are a necessary part of rehabilitation from injury. Prolonged stall rest or wearing a splint or cast results in shortening of the tissues around a joint. Trauma causes protective muscle splitting, which can result in muscle fiber shortening if allowed to persist. Muscle strength is lost when soft tissue adaptively shortens over time. The muscle is tight, yet functionally weak and no longer capable of strong or ballistic contraction.