Flexibility is the anatomical range of movement in a joint or series of joints, and length in muscles that cross the joints to induce a bending movement or motion. Flexibility varies between individuals, particularly in terms of differences in muscle length of multi-joint muscles. Flexibility in some joints can be increased to a certain degree by exercise, with stretching a common exercise component to maintain or improve flexibility. Limberness is the condition of having flexibility to a positive or superior degree, which is also spoken of as a person having flexibility or being flexible. Anatomical elements Joints The joints in a human body are surrounded by synovial membranes and articular cartilage which cover, cushion and nourish the joint and surfaces of each. Increasing muscular elasticity of the joint's range of mobility increases flexibility. Ligaments Ligaments are composed of two different tissues: white and yellow. The white fibrous tissues are not stretchy, but are extremely strong so that even if the bone were fractured the tissue would remain in place. The white tissue allows subjective freedom of movement. The yellow elastic tissue can be stretched considerably and return to its original length. Tendons Tendons are not elastic and are even less stretchy. Tendons are categorized as a connective tissue. Connective tissue supports, surrounds, and binds the muscle fibres. They contain both elastic and non-elastic tissue. Areolar tissue The areolar tissue is permeable and is extensively distributed throughout the body. This tissue acts as a general binder for all other tissues. Muscle tissue Muscle tissue is made of a stretchy material. It is arranged in bundles of parallel fibres. Stretch receptors Stretch receptors have two parts: Spindle cells and Golgi tendons. Spindle cells, located in the center of a muscle, send messages for the muscle to contract. On the other hand, Golgi tendon receptors are located near the end of a muscle fiber and send messages for the muscle to relax. As these receptors are trained through continual use, stretching becomes easier. When reflexes that inhibit flexibility are released the splits then become easier to perform. The splits use the body's complete range of motion and provide a complete stretch. Stretching Flexibility is improved by stretching. Stretching should only be started when muscles are warm and the body temperature is raised. To be effective while stretching, force applied to the body must be held just beyond a feeling of pain and needs