1. Department of Physical Medicine and Rehabilitation, Physical Therapy Program, University of Colorado, Aurora, CO, USA
2. Department of Physical Therapy and Rehabilitation Science, University of Montana, Missoula, MT, USA
3. Department of Clinical and Scientific Affairs, Hanger Clinic, Austin, TX, USA
4. Department of Biomechanics, University of Nebraska at Omaha, Omaha, NE, USA
5. Department of Physical Therapy and Rehabilitation Science, University of California, San Francisco, San Francisco, CA, USA
6. Division of Geriatrics, University of California, San Francisco, San Francisco, CA, USA
7. Department of Orthopedics, University of Colorado, Aurora, CO, USA
8. Department of Geriatrics, Geriatric Research, Education, and Clinical Center, VA Eastern Colorado Healthcare System, Aurora, CO, USA