1. N.G. Kutner, PhD, is Professor of Rehabilitation Medicine, Emory University School of Medicine, 1441 Clifton Rd NE, Atlanta, GA 30322 (USA).
2. R. Zhang, MS, is Senior Associate, Biostatistics and Bioinformatics, Rollins School of Public Health, Atlanta, Georgia.
3. A.J. Butler, PT, PhD, FAHA, is Associate Professor of Rehabilitation Medicine, Emory University School of Medicine.
4. S.L. Wolf, PT, PhD, FAPTA, FAHA, is Professor of Rehabilitation Medicine and Cell Biology, Emory University School of Medicine.
5. J.L. Alberts, PhD, is Associate Professor of Biomedical Engineering, Cleveland Clinic Foundation, and Cleveland FES Center, L. Stokes Cleveland VA Medical Center, Cleveland, Ohio.