UD alum performs shoulder research on Phillies pitchers
Steve Thomas


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9:57 a.m., May 13, 2010----Modern health science researchers are increasingly interested in taking their work from “bench to bedside.” For Stephen Thomas, who recently completed his doctorate at the University of Delaware, the path is actually from the bench to the bullpen.

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Under the advisement of Buz Swanik, associate professor in the Department of Kinesiology and Applied Physiology, Thomas's doctoral research addressed adaptations in the shoulder due to repetitive stress and the role of these changes in overuse injuries.

Thomas recently spent several days with the Philadelphia Phillies pitching staff, where he took measurements of the shoulder joint capsule and the humerus, the bone in the upper arm. The data will be compared with post-season measurements to enable the researchers -- and the team's athletic trainers -- to assess changes over time. The results may serve as the foundation for helping pitchers to avoid injury by modifying their throwing strategy.

“Pitchers have been known to develop adaptations on their throwing arm due to the repetitive stress of throwing a baseball at 90 miles per hour,” Thomas says. “For several years, we have observed that pitchers exhibit an increase in external rotation, which is the rotating back part of the throw, and a decrease in internal rotation, or the rotating forward part of the throw after the ball has left the hand. Clinicians have believed that many of the overuse shoulder injuries we commonly see are due to the large amount of external rotation.

“However, clinicians have recently been examining the deceleration phase of the throw, when a large amount of energy needs to be absorbed to bring the arm to a complete stop after the ball leaves the pitcher's hand. This task is accomplished primarily by the rotator cuff in the back of the shoulder. We believe that over the course of a game, the rotator cuff muscles fatigue, so the joint capsule has to aid in slowing the arm down. The capsule adapts to the repetitive stress placed on it by creating more tissue, or becoming thicker. The thickness accounts for the loss of internal rotation that has been observed in throwers for years.”

Another adaptation that has recently been identified is humeral retroversion, which is a twisting of the humerus, a condition seen in children as young as 6 or 7 years old due to the throwing motion. “It is important to quantify this,” Thomas says, “since the change in motion may be due to these changes in the bone.”

Thomas made his first connection with the Phillies as an undergraduate at Temple University, when he served an internship with the team and met Jeff Cooper, long-time athletic trainer for the Phils and a 1975 graduate of the University of Delaware. The two kept in touch, and Cooper expressed an interest in having Thomas bring his work to the Phillies pitching staff.

“We hope to identify injuries that occur throughout the season and see whether there is a link between those injuries and the physical changes we're measuring,” Thomas says. “Our overall goal is to help clinicians become better at preventing injury in the first place.”

“We also plan on getting performance data from the pitchers to see whether these changes also play a role in performance. This may help pitching coaches determine when a player needs a couple of days off to be more aggressive with his rehab. We're excited to have the opportunity to collect data on athletes of this caliber and in the long run help players of all ages stay healthy and have fun playing the great sport of baseball.”

Thomas earned bachelor's and master's degrees in athletic training at Temple University. He is now a postdoctoral researcher at the University of Pennsylvania in the McKay Orthopaedic Research Laboratory.

Article by Diane Kukich