To collect real-time data on exposure to acceleration and vibrations, about half of all NASCAR drivers “put instrumented, custom-fit mouthpieces inside their mouths,” explained Joel Stitzel, a professor of biomedical engineering at the Wake Forest University School of Medicine in Winston-Salem, N.C.
This helps researchers collect kinematics of drivers’ experience when performing practice laps or on race day. The results were released in the paper, “Pilot Collection and Evaluation of Head Kinematics in Stock Car Racing,” published in the March 2023 issue of Journal of Biomechanical Engineering.
NASCAR has put a lot of effort into addressing driver safety—especially mitigating injury because of severe crashes. Head and neck restraints have reduced the incidence of severe brain injury, for example.
But while crash safety and reduced numbers of concussions in sport grabs all the headlines, the need to understand the effects of regular and expected environmental exposure to subconcussive head impacts are also a concern.
Moreover, while we may have an abundance of data on the protective equipment that comes into play during a high-speed crash scenario, less is known about what typical high-speed laps during practice and on race day expose drivers to.
To better understand driver exposure and to inform future potential equipment or racing policy, in the past NASCAR and other sports collected data using sensors on helmets and other head gear, skin patches, or even from instruments worn in the ears. But the current strategy has proven to work well in this group to collect accurate and precise information about head kinematics.
Because collecting accurate head kinematics is a vital step in assessing driver safety systems and better understanding exposure to injury risk and environmental factors, “The goal of this work is to collect more accurate on-track driver head kinematics using instrumented mouthpieces and get a better understanding of environmental exposure to accelerations and vibrations during real-life, real-time race day and during practice laps,” explained Stitzel in the paper. Research found that a custom instrumented mouthpiece is an excellent method for collecting accurate head acceleration data.
Researchers at the Wake Forest University School of Medicine collected data from NASCAR drivers to monitor potentially brain-damaging accelerations.
Image credit: Wake Forest University School of Medicine
Six DriversThe ongoing study began using 3D dental scans for six stock car drivers. The team took the detailed scans of the top and bottom of drivers’ mouths to make each of them custom, tight-fitting mouthpieces. Approved by the Wake Forest University School of Medicine Institutional Review Board, the retainer-style devices contained motion-sensing instrumentation and partially covered the palate for direct measurement of skull movements.
The mouthpiece sensors contained a tri-axial accelerometer and an angular rate sensor, and “collected data both in interval mode during practice and impact mode during races,” Stitzel explained. A member of the research team configured and deployed each mouthpiece device at each of four tracks and used a custom-built Android app.
Researchers collected data at a total of nine on-track events: three organizational testing environments, three prerace practices, and three races.
Moreover, at each data collection event, research staff recorded video to identify driver location on the track. This, along with quasi-continuous data collection with the mouthpiece enabled extraction and segmentation of complete laps of kinematic data for analysis.
The final study examined data from a total of 42 complete laps from the NASCAR drivers.
The data set included measurements taken during actual NASCAR races.
Image credit: Getty Images
Other Drivers
This NASCAR-funded study has established the feasibility of using an instrumented mouthpiece to measure head movement with the hope of wider acceptance of the device within the larger population of drivers.
This will allow the sport to better monitor head motion and when the movement exceeds certain thresholds, the mouthpiece records those moments, allowing for analyses and future safety improvements, explained John Patalak, vice president of safety engineering at NASCAR in Concord, N.C.
“Back in 2002 we put incident data recorders in the cars and that allowed us to do much better research and made us smarter,” he said. Fast forward to the technology in the mouthpieces, “it’s a remarkably similar approach. We are measuring the kinematics of the driver during a crash. And that's very informative on our human body modeling efforts and our crash reconstructions. It's the same process. We can compare the data we're getting out of the live human drivers in real crashes with what the crash test dummy's instrumentation is telling us.”
This way NASCAR can improve its test processes, Patalak said, “and how we evaluate safety equipment. We’ve already taken data from mouthpiece sensors where drivers have come back and said, ‘that was a hard hit where that's uncomfortable.’ And we've taken those specific cases and—taking deep dives with the mouthpiece sensor data—to understand what types of movement they had experienced. And then we use that to recreate simpler tests, such as drop or sled testing. This way, we use that data as a basis for the speeds or the angles that we're running and where to make improvements. And we can make those improvements—better solutions—faster and with more confidence.”
Stitzel added, “There are other sports where head kinematics need to be studied,” such as soccer and gymnastics. Stitzel and Jillian Urban, an assistant professor of biomedical engineering at Wake Forest, have a patent pending on the mouthpiece instrumentation.
Cathy Cecere is membership content program manager.
