Risk of Brain Injury from Disc Strikes Is “Negligible,” New Research Finds

By Josh Woods, PhD ~

Life is inherently risky. And if you play sports, injury risk lurks around every corner. Even athletes of esports, who compete while sitting down, face significant health problems.

Though seen by some as a whimsical game, disc golf can be a menace to the flesh. Having dealt with several problems myself, I reviewed research on the prevalence of disc golf injuries in two previous posts in Parked—one with an early interview with Disc Golf Strong and the other on stretching. Simply throwing a disc repeatedly, sans ankle turns or catastrophic falls, can wreak havoc on the fibrous tissues that connect muscle to bone.

But there’s one risk that stands above the rest in disc golf land. The mere thought of getting hit in the head by a high-speed driver sends shivers down the spines of the uninsured. If you spend time on disc golf social media, you’ve probably seen the grisly results of a disc strike. Back in 2015, for instance, a woman was blinded in one eye by a disc in Polliwog Park in Southern California.

I’ve spent several hours searching multiple media sources, attempting to quantify the number of such strikes. My only conclusions are that severe disc strikes are rare and that assessing this risk is remarkably difficult.

But one group of researchers recently set out to learn more about the potential harms caused by impacts from discs to the head. Led by Dr. Justin Menickelli, President of the PDGA Board of Directors, the researchers devised an experiment to determine whether flying discs can cause structural head injuries. The study was recently published in the peer-reviewed, academic journal Sports Biomechanics. Read it here.

As illustrated in the video below, the laboratory that carried out the experiment used an air cannon to shoot discs at a male headform. Imagine the head of a crash-test dummy rigged with expensive instruments that measure whether a flying disc can cause internal brain damage.

Video provided to Parked by Justin Menickelli.

The study’s impact measures included “peak resultant linear acceleration, peak resultant angular acceleration, HIC and SI.” In an interview with Parked, Menickelli explained that these indicators have been used in impact tests of other types of sporting equipment, such as baseballs and softballs, and for assessing helmet and airbag safety.

“Peak resultant acceleration, both linear and angular, are essentially the changes in velocity of your head during impact, as when a disc hits it, or when a football player’s helmeted head hits another helmeted head,” said Menickelli.

The HIC and SI measures use the acceleration metrics to estimate the likelihood of a closed head injury, such as a concussion. “Establishing concussion risk based on HIC and SI remains an emerging science,” Menickelli said. “Some people may show concussive symptoms at relatively low HIC and SI scores, while others may show no symptoms at all despite the occurrence of an injury.”

The researchers hypothesized that the risk of concussions from disc strikes depends on the characteristics of the disc and its speed at impact. Two different types of discs were used in the experiment: a putter (Gateway Wizard) and a driver (Innova Destroyer). The discs were propelled by the air cannon at two different speeds (40 mph and 60 mph). They also tested the effects of the disc’s stiffness (rigid versus flexible).

As expected, the study found that “discs traveling at a higher velocity, that have greater mass, of the driver disc type, and are less flexible will generate higher head impact metrics than discs that do not have these traits.”

The fact that you’re better off getting hit by a Wizard than a Destroyer will not surprise many disc golfers. But the study’s general findings are important. Menickelli and colleagues concluded that the likelihood of a disc causing a severe internal head injury is minimal.

They wrote: “While the potential for conflict between disc golfers and other park users may exist, the findings of this study should nonetheless be encouraging to recreation park directors interested in installing a disc golf course as it is reasonable to assume that the likelihood of sustaining a structural head injury from being struck with a baseball is greater than from being struck with a golf disc at the same velocity.”

The study further explained that when a baseball traveling at 60 mph hits a person in the head, the relevant impact metric (HIC value) ranges from 241 to 247. When a disc hits someone’s head, the HIC values range from 0.6 to 11.5. “These low HIC values are so far below the current regulatory limits in automotive crash severities as to be considered negligible,” the authors stated.

While the study concluded that discs pose a lower risk than other types of sports equipment, it did not suggest that disc golf is safe. Disc strikes can cause significant pain and result in serious harm to a person’s skin, eyes and other facial features. As noted in the study, “rules and regulations should be posted to inform park users of the risks of flying discs.”

Menickelli and his colleagues have established a crucial starting point for the discussion of disc golf safety. If courses continue to proliferate across the world, park departments and community stakeholders will increasingly ask questions about the risks associated with disc golf. This new study provides a few precise and reliable answers.

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Parked is made possible in part by a grant from the Professional Disc Golf Association.