The Medical College of Wisconsin in Milwaukee reports that the height of the pitcher's mound can affect the athlete's throwing arm motion, leaving a pitcher vulnerable to injuries because of stress on the shoulder and elbow.
Dr. William Raasch, the college's associate professor of orthopedic surgery and head team physician for the Milwaukee Brewers, led the study, which was funded by Major League Baseball.
"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," Raasch said. "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 study from last year's spring training found that, compared to flat ground, pitchers using a 10-inch mound experience increased pressure on their shoulder, which could result in injuries such as a torn rotator cuff or labrum.
"The most notable kinematic difference was the increase in shoulder external rotation at foot contact," Raasch said. "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."
While the study did not result in enough data to recommend reducing the 10-inch mound height, which became standard in 1968 and also used in college and high school baseball, Raasch said the findings give trainers information that can help them determine if pitchers would be better off practicing on flat ground, especially after an injury.