After the walking test is completed, subjects' leg muscle strength is measured with a special device while they perform three activities. First, they sit on a special chair with their leg and foot placed in an apparatus that measures their strength, then lie on their back, then on their stomach, and then stand on one foot holding a bar to balance during part of one activity. During the activities, their reflexes are tested, they are asked to move their legs, and their legs are moved for them.