The sport of soccer features countless moments where movement and judgment calls happen in less than a second.
For athletes, what separates the good from the great — and the elite on the FIFA World Cup stage — is the brain’s basal ganglia, a group of brain structures linked together to handle complex processes that affect a person’s body.
“The main thing (athletes) possess is very detailed models of how to interact in any situation,” said Eric Yttri, a Carnegie Mellon University professor who studies biomedical engineering and neuroscience.
“There is some truth in the adage, you can’t teach an old dog new tricks,” he said. “Early in life, the brain is good at creating connections, physical connections called synapses. At a young age, learning and creating these physical connections lays the groundwork for the rest of their career.”
As the FIFA World Cup runs through July 19 across the U.S., Canada and Mexico, people across the world are enjoying the fast-paced and fluid nature of soccer. In Pittsburgh, a team of experts are scrutinizing the biomechanics behind the complex plays.
Yttri notes that often, FIFA boasts storylines of an old veteran challenged by a new, upstart star in matches. It’s pretty even as to who will emerge victorious. But Yttri notes older players benefit from experience when it comes to close plays.
“In the sports world, we think of practicing. In the neuroscience world, we think of, ‘fire together, wire together’ ” Yttri said. “The more times you try something with different scenarios, every time you practice a different scenario, neurons fire together. More practice across more diverse scenarios lead to a richer, more diverse repertoire and greater control.”
Reinforced learning also helps the most elite players in soccer when it comes to the sport’s uncertainties, like facing off against different opponents, unexpected ball bounces and weather conditions.
“You will learn a model of all of these scenarios and pick and choose what’s best. If you don’t have as much experience to choose from, you’ll be slower to adapt and tune movements,” Yttri said. “With more experience, you’ve seen more and you can be more efficient in how you apply your knowledge.”
Players aren’t the only ones on the pitch grappling with split-second decisions. Referees also are in a situation where they need to react quickly — but more importantly, correctly, Yttri said.
The same mechanism exists for athletes, said Yttri, himself a former high school soccer official.
“The tradeoff the brain’s basal ganglia has to go through is on a knife’s edge,” he said. “If a referee waits one second, two seconds to make a decision, that doesn’t matter. The crucial thing is that it’s correct. If you’re sprinting and face an uncertain situation, should I veer left or right, that tradeoff is acting impulsively or waiting to make a better decision. Sometimes you have to abandon thinking with hesitation and go with decades of practice.”
Eni Halilaj is an engineering professor at CMU who specializes in biomechanics of movement. She works on wearable sensors to study how athletes move.
Professional soccer players, on average, suffer one to two injuries per season. Common injuries include muscle and ankle sprains.
“They’re asking more of their bodies,” Halilaj said. “In elite athletes, injuries happen even in peak conditions because they’re operating near the limits of human performance.”
Less common, but more detrimental, are tears to the ACL, a knee ligament.
“It can be career-ending for some people,” she said. “What we’re trying to do in research is better understand and tailor recovery so athletes can return to sport as safely as possible.”
That’s where Halilaj sees potential with wearable sensors to better support decisions about rehabilitation and safe return to play.
Researchers hope more personalized rehabilitation informed by wearable sensors eventually could shorten recovery times and lower the risk of reinjury.
“My hopes are that wearable sensors will be used more for performance optimization in the future,” Halilaj said. “Current wearable devices can estimate movement quantity but are less capable of providing information on movement quality. We are focusing on quality to help athletes, coaches and clinicians make better decisions.”