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Higher Pitching Mounds Mean More Injuries For Baseball Players

For the third year in a row, American professional baseball's major leagues opened their season in Japan. Baseball is becoming more popular there, as well as in Korea, and it remains popular throughout Latin America. But with the spread of baseball comes the potential for new types of injury. Rose Hoban explains.

William Raasch is an orthopedic surgeon at the Medical College of Wisconsin. He's also the doctor for the Milwaukee Brewers baseball team, and works with injured pitchers, helping them rehabilitate. He noticed that when they pitched on flat ground, they had few problems. But as they began throwing from the 25-centimeter high pitcher's mound, they started to have more problems.

So, Raasch analyzed the problem using something called a 'motion analysis system.' It's the same process computer programmers use to create video games. "This is a system where you put a number of reflective markers on certain sites of the body, and then basically you have eight digital cameras that record those markers," he explains. "Systems like this have been around for a while. The one we utilize is sort of a state-of-the-art system. We use more markers than most previous studies had used and … so we got lots and lots of information."

Raasch and his colleagues took that information about the movements and the motions, and calculated the stresses that occur on the shoulder and the elbow. They recorded data from pitchers throwing on flat ground, then on mounds that were 15 centimeters high, 20 centimeters high and the regulation 25 centimeters mound.

Powerful computers took all that information and processed it to find where stresses occur on the shoulder and elbow, and when they occur.

"We found that, really, the major difference was at that cocking phase, when the arm was brought all the waaaaay back behind the body," Raasch says, "which is actually one of the positions that's the most stressful part on the shoulder." The researchers saw differences in two of the stresses. "One was what we call adduction torque, the ability to pull that arm down, and the other was what we call superior sheer. In other words, the ball of the arm bone was being forced downward and the body was trying to control and keep the shoulder in place by pulling upwards."

Raasch also found stresses on the elbow and changes in the timing of the throw. These were all most pronounced when the pitcher was standing on a mound. They decreased when pitchers threw from flat ground. But Raasch didn't see any difference in the speed of the ball when pitchers threw from different heights.

"This data is beginning to show us that if someone is throwing the baseball, and they're putting a lot of stress on the shoulder, well, it just makes sense that if you stress something a lot, it may break," Raasch says.

The 25 centimeter mound is used throughout the world as the standard in major leagues, minor leagues and collegiate athletics. In the United States, that height became the standard in 1968. Mounds used to be even higher.

Raasch isn't sure what will happen with his research now and he's continuing to collect data. He says someday, perhaps, this information might change the way pitchers throw, it might change the heights of pitchers' mounds or it might just help doctors treat pitchers who inevitably get injured.

Raasch presented his research at a meeting of the Major League Baseball Team Physicians Association and the Professional Baseball Athletic Trainers Society.