1. Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA Lindsay
2. Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
3. Applied Biomechanics Research Laboratory, Department of Kinesiology, College for Health, Community and Policy, The University of Texas at San Antonio, San Antonio, Texas, USA
4. Division of Biostatistics, Institute for Health and Equity, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
5. Division of Biostatistics, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
6. University of Michigan Concussion Center, University of Michigan, Ann Arbor, Michigan, USA
7. Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana, USA
8. Department of Physical Medicine and Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
9. Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA
10. Department of Athletics, School of Behavioral and Applied Sciences, Azusa Pacific University, Azusa, California, USA
11. Department of Exercise and Sport Science, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
12. Institute for Critical Technology and Applied Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
13. Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware, USA
14. Department of Exercise Science, California Lutheran University, Thousand Oaks, California, USA
15. Department of Family and Community Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA
16. Departments of Family Medicine and Orthopaedic Surgery, University of California, Los Angeles, Los Angeles, California, USA
17. Departments of Orthopaedic Surgery and Rehabilitation Medicine and Pediatrics, University of Chicago, Chicago, Illinois, USA
18. Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
19. School of Applied Health, California State Polytechnic University, Humboldt, Arcata, California, USA
20. Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
21. Department of Community Health and Family Medicine, University of Florida, Gainesville, Florida, USA
22. Orthopaedic and Sports Medicine Research, United States Military Academy, West Point, New York, USA
23. Division of Adolescent Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, USA
24. Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, Michigan, USA
25. School of Optometry, Indiana University Bloomington, Bloomington, Indiana, USA
26. Department of Athletics, United States Air Force Academy, Air Force Academy, Colorado, USA
27. Investigation performed at the Medical College of Wisconsin, Milwaukee, Wisconsin, USA