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Characterizing head acceleration events in Stock Car Auto Racing by head kinematics derived Principal Direction of
Cole D Smith1,2, Zoie R Mink1,2, N Stewart Pritchard1,2
1Department of Biomedical Engineering, Wake Forest School of Medicine, Winston-Salem, North Carolina.
Traffic Injury Prevention
|May 28, 2026
Summary
Head impact directionality (PDOF) significantly affects NASCAR driver exposure. Right side impacts are most frequent and high magnitude, while frontal oblique impacts cause greater brain tissue deformation, informing targeted safety improvements.
Area of Science:
- Biomechanics
- Motorsports Safety
- Neurotrauma
Background:
- Drivers face non-concussive head acceleration events (HAEs) despite safety advances.
- Understanding impact direction is crucial for mitigating head injury risks in racing.
Purpose of the Study:
- To evaluate if the Principal Direction of Force (PDOF) influences head impact exposure in NASCAR Cup Series drivers.
- To analyze the relationship between impact direction and head kinematics during racing events.
Main Methods:
- Collected head kinematic data from 20 NASCAR drivers using instrumented mouthpiece sensors.
- Analyzed 4,478 head impacts, categorizing them by event type, track, and eight PDOF directions.
- Utilized mixed-effects models to assess associations between PDOF and head kinematics, including peak linear/rotational acceleration and Diffuse Axonal Multi-Axis General Evaluation (DAMAGE).
Main Results:
- Right side impacts were most frequent (55.3%) and had high magnitudes for linear and rotational acceleration.
- Frontal, right side, and rear impacts showed greater peak linear acceleration than left side and oblique impacts.
- Frontal oblique impacts demonstrated the highest magnitudes for rotational velocity and DAMAGE, indicating greater brain tissue deformation.
Conclusions:
- Principal Direction of Force (PDOF) is associated with head impact frequency and magnitude in NASCAR drivers.
- Findings highlight the importance of impact directionality in assessing head injury risk.
- Results offer a framework for developing targeted safety interventions in motorsports and contact sports.
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