1. Department of Biomedical Engineering, Division of Geriatric Medicine, Muscle Mechanics Laboratory, University of Michigan, Ann Arbor, Michigan.
2. Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, Michigan.
3. Muscle Mechanics Laboratory, University of Michigan, Ann Arbor, Michigan.
4. Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan.
5. Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan.