1. J.K. Tilson, PT, DPT, NCS, is Assistant Professor of Research Physical Therapy, Division of Biokinesiology and Physical Therapy, University of Southern California, 1540 E Alcazar St, CHP 155, Los Angeles, CA 90089 (USA).
2. K.J. Sullivan, PT, PhD, FAHA, is Associate Professor of Clinical Physical Therapy, Division of Biokinesiology and Physical Therapy, and Associate Chair and Director, Doctor of Physical Therapy Program, University of Southern California.
3. S.Y. Cen, PhD, is Assistant Professor of Research, Division of Biokinesiology and Physical Therapy, University of Southern California.
4. D.K. Rose, PT, PhD, is Research Assistant Professor, Department of Physical Therapy, University of Florida, Gainesville, Florida.
5. C.H. Koradia, PT, is Physical Therapist, First Class Physical Therapy, Brooklyn, NY. At the time of the study, she was an MS student in the Graduate Program in Biokinesiology and Physical Therapy, University of Southern California.
6. S.P. Azen, PhD, is Professor and Co-Director of Biostatistics, Division of Biostatistics, Department of Preventive Medicine, Keck School of Medicine, University of Southern California.
7. P.W. Duncan, PT, PhD, FAHA, FAPTA, is Professor and Bette Busch Maniscalco Research Fellow, Division of Doctor of Physical Therapy, Department of Community and Family Medicine; Professor, School of Nursing; and Senior Fellow, Center for the Study of Aging and Human Development, Duke University, Durham, North Carolina.