This study will collect information on the different ways people control limb and body movements. This information will be used to develop a database on normal movements and adaptive movements of people who have diseases that affect the way they move. The database will serve as a tool to improve diagnosis and treatment of patients with movement-related problems.

Volunteers over the age of 4 who have normal movement patterns or who have developed different ways to perform movement tasks may be eligible for this study. A physical therapist will screen candidates to determine their strength, flexibility and range of motion of joints.

Participants will be asked to perform movements such as walking, walking up or down stairs, standing quietly or reaching for an object. For the test, the arms and legs are wrapped with a soft, rubber-like material to which small plastic reflective balls are attached. A piece of firm material called a shell may be attached to the rubber sleeves or other areas of the body. Then the volunteer performs the specified task several times while special cameras record the movement. The cameras only record the positions of the reflective balls during movement, not the person's face or body. Electrical activity in the muscles also may be measured, using small metal electrodes attached to the surface of the skin with an adhesive bandage.