Straight ahead running demands a certain amount of agility for rapid stride turnover. Agility involves rapid change of limb position or rapid change of direction, and it requires mobility in the soft tissues that surround a joint. The greater the agility one possesses, the greater the ability to accelerate rapidly or to maneuver around or over an obstacle. 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.