1. Office for Sport Concussion Research, University of Arkansas , Fayetteville, AR 72701, USA
2. Department of Orthopaedic Surgery, UPMC Sports Medicine Concussion Program , Pittsburgh, PA 15260, USA
3. Inova Sports Medicine Concussion Program , Fairfax, VA 22031, USA
4. UPMC Rehabilitation Institute , Pittsburgh, PA 15203, USA
5. College of Osteopathic Medicine, University of New England , Biddeford, ME 04005, USA
6. Department of Physical Therapy, University of Pittsburgh , Pittsburgh, PA 15260, USA
7. Department of Orthopaedic Surgery, University of Pittsburgh , Pittsburgh, PA 15260, USA