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Height of Pitcher's Mound Can Strain Shoulders

WEDNESDAY March 26, 2008 -- The height of a pitcher's mound can influence the risk of stress-related elbow and shoulder injuries, suggests a study led by the head team physician for the Milwaukee Brewers.

The study included 20 pitchers from Major League Baseball organizations and Milwaukee-area NCAA Division I-A college teams.

"Our researchers employed a motion analysis system using eight digital cameras that recorded the three-dimensional positions of 43 reflective markers placed on the athletes' bodies," study leader Dr. William Raasch, an associate professor of orthopedic surgery at the Medical College of Wisconsin in Milwaukee, said in a prepared statement. "Then we analyzed the pitching motion at mound heights of the regulation 10 inches, along with eight-inch and six-inch mounds, as well as having the athletes throw from flat ground."

The researchers examined pitching motion position and velocity, along with the forces and torques generated at the shoulder and elbow.

"We found that compared to flat ground, pitchers using a 10-inch mound experience an increase in superior shear and adduction torque in the shoulder -- meaning there's a greater amount of stress on the joint surface and surrounding structures," Raasch said.

"That greater stress may result in injury to the shoulder including tearing of the rotator cuff or labrum, which may result in surgery and long-term rehabilitation. It also can make it difficult for the athlete to replicate the same throw and develop a consistent strike," he said.

He and his colleagues found that the "most notable kinematic difference was the increase in shoulder external rotation at foot contact. This probably represents a change in the timing of the foot contact relative to arm position, because the foot lands earlier in the pitch delivery during flat ground throwing than with a slope."

This study didn't provide enough data to make a recommendation on whether the standard 10-inch mound height should be changed, but the findings do offer trainers information that may help them determine if pitchers should practice on flat ground, especially after an injury, Raasch said.

The study, funded by Major League Baseball (MLB), was presented at a joint session of the Major League Baseball Team Physicians Association and Professional Baseball Athletic Trainers Society, held at the MLB winter meetings.

More information

The American Academy of Orthopaedic Surgeons has more about throwing-related injuries in the elbow.

Posted: March 2008


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