Study leader Dr. William Raasch of the Medical College of Wisconsin in Milwaukee presented the findings at the 2007 Major League Winter Meetings.

"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 that may result in injury to the shoulder including tearing of the rotator cuff or labrum," Raasch said in a statement.

The study did not result in enough data to recommend reducing the 10-inch mound height, which became standard in 1968, but Raasch said the findings can help trainers determine if pitchers would be better off practicing on flat ground -- especially after an injury.

The researchers observed 20 Major League or NCAA Division I-A pitchers during 2007 spring training in Arizona and at the Froedtert & Medical College Sports Medicine Center in Milwaukee using eight cameras to record the three-dimensional positions of 43 reflective markers on the athletes' bodies as they threw from 10-inch, 8-inch, and 6-inch mounds as well as flat ground.