1. Worcester Polytechnic Institute, Worcester, Massachusetts, USA.
2. Spaulding Rehabilitation Hospital, Charlestown, Massachusetts, USA.
3. University of Colorado School of Medicine, Aurora, Colorado, USA.
4. Department of Orthopaedic Surgery, Stanford University, Stanford, California, USA.
5. Stanford Medical Center, Redwood City, California, USA.
6. Department of Orthopaedic Surgery, University of California, Los Angeles, Santa Monica, California, USA.
7. Human Performance Laboratory, Stanford University, Stanford, California, USA.