Drill-Specific Head Impacts in Collegiate Football Practice: Implications for Reducing “Friendly Fire” Exposure

  • Breton M. Asken
  • Zechariah S. Brooke
  • Taylor C. Stevens
  • Paul G. Silvestri
  • Matthew J. Graham
  • Michael S. Jaffee
  • James R. Clugston
Special Issue on the NCAA-DoD CARE Consortium Research


This study investigated drill-specific head impact biomechanics in a Division 1 collegiate football team using the Head Impact Telemetry System (HITS). A total of 32,083 impacts were recorded across 2 years of practices. Precise tracking of instrumented athletes, head impacts, and drill participation allowed quantification of hits sustained per person per minute (H/P/M) for each specific drill. We found significant H/P/M variability between 14 drills and player position, ranging from 0.02 to 0.41 H/P/M for Linemen and 0.01 to 0.15 H/P/M for Non-Linemen. Impact magnitude data are also reported for practice term (Spring, Training Camp, In-Season) and dress-type (Helmets Only, Spyders, Shells, Full Pads). Recommendations for shortening high-risk drills, based on H/P/M drill impact frequencies, suggest possible “friendly fire” reductions of 1000 impacts for Linemen and 300 impacts for Non-Linemen over their collegiate career. Over 80% of potentially avoidable head impacts were attributable to just three drills—“Team Run,” “Move the Field,” and “Team.” Recommending drill-specific modifications based on practical considerations (the drill’s impact frequency, dress-types when performing the drill, and duration) could improve acceptance from coaches and efficiently reduce head impact exposure without drastically altering overall practice structure.


HIT System Subconcussive Concussion Repetitive head impact exposure Football practice drills Impact frequency 



We wish to thank the University of Florida’s University Athletic Association for their continued support of concussion research at the institution. We also thank the student-athletes who participated in this study.

Conflict of interest

The HIT System was purchased with funding provided in part by the Florida High Tech Corridor Council (FHTCC) and Banyan Biomarkers, Inc., with support from the NFL-GE Head Health Challenge. The authors declare no conflicts of interest pertaining to this study. BA received funding support from Banyan Biomarkers, Inc. for efforts related to statistical analysis and manuscript preparation. JC received support through the NCAA-DOD CARE Consortium as site PI (Office of the Assistant Secretary of Defense for Health Affairs through the Psychological Health and Traumatic Brain Injury Program under Award NO W81XWH-14-2- 0151), Banyan Biomarkers, Inc., and the Florida High Tech Corridor.

Supplementary material

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Copyright information

© Biomedical Engineering Society 2018

Authors and Affiliations

  • Breton M. Asken
    • 1
  • Zechariah S. Brooke
    • 2
  • Taylor C. Stevens
    • 3
  • Paul G. Silvestri
    • 2
  • Matthew J. Graham
    • 2
  • Michael S. Jaffee
    • 4
  • James R. Clugston
    • 2
    • 5
  1. 1.Department of Clinical and Health PsychologyUniversity of FloridaGainesvilleUSA
  2. 2.University Athletic AssociationUniversity of FloridaGainesvilleUSA
  3. 3.Applied Physiology and KinesiologyUniversity of FloridaGainesvilleUSA
  4. 4.Department of NeurologyUniversity of FloridaGainesvilleUSA
  5. 5.Department of Community Health and Family MedicineUniversity of FloridaGainesvilleUSA

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