Professor helps track athletes go for the gold

He’s not a coach and he’s never been to the Olympics, but Carolina’s Bing Yu has helped athletes train for eight Summer Games, including the 2016 games in Rio de Janeiro.

Yu is a professor in Division of Physical Therapy as housed in the School of Medicine’s Department of Allied Health Sciences. He uses his expertise in biomechanics to analyze the performance of members of the U.S. Track and Field team and to suggest changes to improve technique and avoid injury. His work with discus thrower Stephanie Brown Trafton helped her win a gold medal in the 2008 Olympics in Beijing.

“Biomechanics is the study of how the human body moves,” Yu said. “People do not realize how science is involved in sports.”

Yu didn’t know about that connection either when he took the entrance exam for college back in China. Both of his parents were doctors, so he figured he would be a doctor, too – a surgeon, he hoped.

He had already ruled out his first career choice, professional athlete. He was too short to compete professionally in his sport of discus throwing, and he had stopped competing in the javelin throw because, ironically, “I injured my elbow because my technique was not right,” he said.

But Yu didn’t go to medical school. When he scored high in math and physics as well as chemistry, the Ministry of Education placed him at Beijing Sport University. His test scores and athletic background made Yu “the best material to study biomechanics,” administrators told him.

He didn’t know what biomechanics was back then, not that it mattered.

“The government has the final say in where you go,” Yu said. “After I started, I liked it, and that’s the best situation. I’m the lucky one.”

Yu began to work with U.S. Olympic athletes when he was a doctoral student at University of Iowa and an assistant to a professor who was doing biomechanics research for the track and field team.

To analyze an athlete’s performance, Yu videotapes the athlete in motion from different angles. Then, back at his office, he reconstructs that motion in a 3-D wireframe animated model that he can rotate in any direction, including from above. Each joint has its own coordinates, which Yu uses to calculate movement. He then compares the athlete’s technique to the wire-frame-diagram model of an elite athlete in the same sport and highlights the differences, frame by frame. The results and recommendations go into a personalized booklet for the athlete and the coaches.

Take Brown Trafton, the discus thrower, for example. Yu noticed that her finish position wasn’t consistent. He pointed to the wire-frame-diagrams that showed how much more an elite athlete twisted her torso compared to Brown Trafton. “If you twist more, you have more room to accelerate the discus,” Yu said. “We figured out that was the problem for Stephanie. That was one of the reasons she could not gain as much speed for the final part of the throw.”

Yu noticed something else about Brown Trafton’s technique. “Every time she had a good throw, she had a very unique finish position,” he said. “We found out some key factors for her to accomplish before the final part of a throw. The key was to have that finish position for every throw.”

When Brown Trafton made her first toss in the 2008 Olympic finals, Yu saw that she was in the correct finish position.

“She did exactly what we said she should do,” Yu said proudly. As the round continued, though, Brown Trafton strayed from the improved technique and her throws fell short. “She tried very hard to improve her performance and she did not do very well. Sometimes they try too hard,” Yu said. But her first toss proved to be good enough for the gold, so the process paid off.

Sometimes coaches inadvertently pass on bad techniques because that’s the way a sport has always been done. In the javelin throw, for instance, many coaches insisted that their athletes keep the left knee straight. But the technique often resulted in an injury to the athlete’s anterior cruciate ligament, a two-inch strip of tissue that controls the back and forth motion of the knee.

“That straight knee landing actually adds a dramatic load to the left knee and the ACL,” Yu said. He discovered that connection watching a competition tape that happened to capture an injury in progress — to a javelin thrower using the straight-knee technique.

Yu used the data for a paper presented to a scientific journal and also presented the findings to coaches. By comparing the injury tape to an elite athlete’s performance, Yu could show that landing with a flexed left knee not only reduced the load on left knee but also improved performance.

Yu worked with male and female discus and javelin throwers at the July 1-10 track and field trials in Eugene, Oregon. He joined the team again at the pre-Olympic training camp July 25-Aug. 10 in Houston, Texas. But he and other scientists won’t be allowed to move into the Olympic village in Rio de Janeiro with the athletes, so Yu will be following the Olympics from home.

At this year’s trials, 2008 gold medalist Brown Trafton had the third best qualifying throw, but placed fifth in the final round. Only the top three finalists make the Olympic team, so Brown Trafton will not be going to her fourth Olympics.

Another discus thrower that Yu worked with closely was defending national champion Gia Lewis-Smallwood. Yu went to her training site in Champaign, Illinois, as she struggled with a March injury, but Lewis-Smallwood could not recover in time to qualify for the Olympics.

Yu’s specialized work with these elite athletes, which is funded by U.S. Track and Field, is only a small part of what he does. Lately his research has focused on the prevention of ACL injuries, especially in young and amateur athletes.

“The soccer moms are so happy we are doing that,” he said. These non-contact injuries can be prevented, with proper techniques. As with the professional athletes, amateurs should keep their knees bent and land softly to avoid tearing the ACL.

Yu is currently working with Duke orthopedic surgeon William Garrett to develop a knee brace that will train athletes to bend their knees. Called a “knee extension constraint brace,” this device keeps the knee from getting locked in a straight position.  “We’re testing it, and a preliminary study has been published,” Yu said. “Now we are doing a bigger scale study.”

The stakes are high, for weekend warriors and the pros. “If you have an ACL injury, you are done,” Yu said.