Author Contributions: Dr Tucker had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Tucker, Vogel, Lincoln, Dunn, Allen, Castle, Heyer, Pellman, Strollo, Wilson, Yates.
Acquisition of data: Tucker, Vogel, Lincoln, Dunn, Ahrensfield, Allen, Castle, Heyer, Yates.
Analysis and interpretation of data: Tucker, Vogel, Lincoln, Dunn, Ahrensfield, Castle, Heyer, Pellman, Strollo, Wilson.
Drafting of the manuscript: Tucker, Vogel, Lincoln, Dunn, Pellman, Strollo, Wilson, Yates.
Critical revision of the manuscript for important intellectual content: Tucker, Vogel, Lincoln, Dunn, Ahrensfield, Allen, Castle, Heyer, Pellman, Strollo, Wilson, Yates.
Statistical analysis: Lincoln, Dunn.
Obtained funding: Tucker, Lincoln, Dunn, Pellman, Yates.
Administrative, technical, or material support: Tucker, Vogel, Lincoln, Dunn, Ahrensfield, Allen, Castle, Heyer, Pellman, Strollo, Wilson, Yates.
Study supervision: Tucker, Vogel, Lincoln, Dunn, Allen, Yates.
Financial Disclosures: None reported.
Funding/Support: This study was funded by the National Football League (NFL).
Role of the Sponsors: The NFL had no role in the design and conduct of the study, in the collection, analysis, and interpretation of the data, or in the preparation, review, or approval of the manuscript. Assistance in study design was provided by Elizabeth A. Carter, MPH, and Jianhui Zhu, MD, PhD (Medstar Research Institute, Washington, DC), and by Jason G. Umans, MD, PhD (Penn Medical Lab of MedStar Research Institute, Washington, DC).
Additional Contributions: We thank Henry R. Black, MD (New York University Medical Center), for substantive critical review of the manuscript; Marty Lauzon, ATC, and Ron Medlin, MS, ATC (members of the NFL Subcommittee on Cardiovascular Health), for assistance in data collection; the athletic training staffs of the 12 participating teams; and the head athletic trainers and medical team physicians (Bill Tessendorf, MA, ATC; Thomas White, MD; Bud Carpenter, ATC; Ryan Vermillion, ATC; Howard Katz, MD; Tim Bream, ATC; Chris Hanks, ATC; Keith Burch, MD; Al Bellamy, MS, ATC; Dean L. Kleinschmidt, ATC; James Muntz, MD; Kevin Bastin, ATC; Douglas W. Robertson, MD; Hunter Smith, MA, ATC; Dave Hammer, ATC; David T. Murray, MD; Michael D. Ryan, PT, ATC, PES; Gary W. Dorshimer, MD; Rick Burkholder, ATC; Chris Peduzzi, ATC; John A. Norwig, ATC; Daniel Garza, MD; J. D. Ferguson, MS, ATC; Anthony Casolaro, MD; John Burrell, ATC; Bubba Tyer, ATC; John Mellody, MS, ATC; Sam Ramsden, ATC), and numerous assistant athletic trainers from each team. We also thank the NFL Commissioner's Office; the NFL Players Association; the late Gene Upshaw; Thom Mayer, MD; and the participating NFL teams (the Baltimore Ravens, Buffalo Bills, Carolina Panthers, Chicago Bears, Detroit Lions, Houston Texans, Indianapolis Colts, Jacksonville Jaguars, Philadelphia Eagles, Pittsburgh Steelers, San Francisco 49ers, and Washington Redskins). Lyn Camire, MA, ELS (Department of Orthopaedics, Union Memorial Hospital, Baltimore, Maryland), contributed to the writing and editing of this manuscript and was compensated for her contribution. For all others acknowledged, no compensation was received.