When Amanda Esquivel, assistant professor of mechanical engineering at UM-Dearborn, began planning her latest study comparing head acceleration in boys and girls lacrosse players, she knew that one of her first challenges would involve a fundamental technical problem. Unlike their male counterparts, female lacrosse players do not wear helmets. This quickly precluded the use of the established helmet-mounted sensor systems that had already been developed to study headbutts in soccer players.
Instead, she bought a headband-mounted system that athletes could strap on with their goggles on — which sounds like a simple solution. Except that when using another sensor that had never been called into research service in this way, her team had to validate it properly so they could get the kind of data they were looking for.
“When you put a sensor in a helmet or headband, you’re really measuring what’s going on inside the helmet or headband — not what’s going on in the middle of the head,” Esquivel said.
To circumvent this problem, they first outfitted the head of a crash test dummy with the sensors mounted on the headband and a second set of sensors in the center of the head. The team then subjected the dummy to all sorts of impacts. Finally, with a little mathematical modeling, they correlated the information from the two sensors – so the data coming from the outside would be a decent surrogate for the inside.
Even then, Esquivel says this type of modeling “isn’t perfect.” And she’s quick to point out that even after you’ve gone to all the trouble of validating the sensors and collecting data on real athletes, you’ve still only put a few bricks in the wall that the Researchers ultimately hope to build. This, of course, determines the impact of such effects on our brains and eventually sets some prescribed thresholds for athletes.
Such is the nature of sports injury research today, where many big conclusions may be decades away and breakthroughs come in small chunks rather than big dramatic leaps. Still, wearable sensors could prove to be a game-changing innovation. Compared to football, which now has 20 years of research, Esquivel says helmetless sports, women’s sports and youth sports are underexplored areas and the new technology could allow researchers to address all sorts of important questions. “It’s important to remember that even if we were able to draw conclusions from what we’ve learned in 20 years of studying adult male football players, it still wouldn’t necessarily tell us everything we do.” For example, football players or lacrosse players need to know about men – or children who play the same sports.”
In addition to expanding studies to other sports, the wearable technology could help researchers study a broader range of sports injuries. For example, one of Esquivel’s most recent projects is a collaboration with James Ashton-Miller, Professor of Mechanical Engineering Research at UM, who is studying one of the more common catastrophic knee injuries in sports. So far, it has often been assumed that a cruciate ligament tear is an acute injury caused by a single serious event that damages the ligament. But in research using cadavers, Ashton-Miller showed that cruciate ligament tears can sometimes result from cumulative stress on a ligament.
Now Esquivel and Ashton-Miller are preparing a study that would use the wearable sensor system to study the same questions in live athletes. “You can’t just extrapolate from what you see on cadavers to what you see on living people, because the body always repairs itself,” says Esquivel. “But if we were observing a similar phenomenon, our goal would be to figure out what would be a dangerous stress cycle for an ACL, and possibly even identify actions or movements that specifically contribute to that type of stress.”
Ultimately, if they could draw conclusions through this new study, it could be used as the basis for an early warning system, giving athletes a warning to rest and recover; or it could simply help coaches and coaches minimize movements in practice that can lead to cruciate ligament overuse injuries.
Such a breakthrough, says Esquivel, is still a few steps away. But in a field where headline conclusions are earned with one small study at a time, each step naturally counts as a step in the right direction.