1. a Department of Physical Therapy , University of Evansville , Evansville, IN, USA
2. b Center for Physical Ergonomics, Liberty Mutual Research Institute for Safety , Hopkinton, MA, USA
3. c Department of Environmental Health , Harvard School of Public Health , Boston, MA, USA
4. d Department of Orthopaedic Surgery , Brigham and Women's Hospital and Harvard Medical School , Boston, MA, USA