1. Department of Rehabilitation Medicine, University of Washington, Box 356490, 1959 NE Pacific St, Seattle, WA 98194-6490, USA; and Department of Health Services, University of Washington, Seattle, Washington, USA
2. Department of Rehabilitation Medicine, University of Washington, Seattle, Washington, USA
3. Department of Physical Therapy, Wichita State University, Wichita, Kansas, USA
4. Department of Physical Therapy, California State University, Long Beach, Long Beach, California, USA