man feeling stressed or scared with tennis racket. (© kues1 - stock.adobe.com)
DALLAS — If you ask someone what sports cause concussions, football or ice hockey are likely at the top of people’s lists. However, that does not mean other sports are safe from head injuries. A new study has found that even getting whacked in the head with a tennis ball has enough power to cause a mild traumatic brain injury.
While the chances of suffering a concussion from this are rare, the research shows it is possible when the velocity of a tennis ball is over 40 meters per second. That’s faster than a cheetah on the run.
People were more likely to sustain a head injury from a tennis ball hitting the side of their head versus their forehead or top of the head. Additionally, the risk of a concussion went up when someone hit the ball at a 90-degree angle compared to a 30 or 60-degree angle. The spinning of the ball, however, did not have an impact on causing a head injury.
“Understanding and protecting against head injuries induced by tennis ball impacts is very important, given that tennis is a worldwide sport with tens of millions of participants every year,” says study co-author Xin-Lin Gao, a mechanical engineering professor at Southern Methodist University, in a media release.
Concussions are considered mild traumatic brain injuries because they typically aren’t life-threatening. However, they can produce discomforting symptoms such as headaches, dizziness, and concentration issues for weeks or months.
The study had two models: a computer-generated tennis ball and an anatomically detailed model of a man’s head. The head model came from the Global Human Body Models Consortium, which creates realistic 3D models of people for crash simulations. It’s a common tool for studying brain injuries from head trauma. While Gao says the results are likely similar for women and children, more research on these two groups is still necessary.
The models allowed the researchers to simulate how a brain would respond when subjected to strong external forces. Several mathematical algorithms helped to create characteristics of the ball and the man’s head. For example, one algorithm tested for rubber elasticity, used to represent brain tissue behavior. All of these measurements gave researchers an opportunity to mimic the force of a tennis ball at different speeds and the site of impact on a player’s head.
In their simulations, they found the speed of the ball was enough to cause brain tissue to bang against the skull, causing a mild concussion. The results were compared and verified by human cadavers with head injuries and observations of people with known concussions.
The study is published in the ASME Journal of Applied Mechanics.
