The higher the pitcher's mound in baseball, the more effective the pitcher -- and the more likely he is to hurt his arm.

The higher the pitcher's mound, the more leverage a pitcher has, and the greater the angle at which the ball crosses the batter's box. This makes it more difficult to hit the ball squarely.

After the 1968 season, which was dominated by pitchers (Boston's Carl Yastrzemski won the American League batting championship that year with the remarkably low batting average of .301), Major League Baseball ordered the pitching mound be lowered from 15 inches to 10 in order to generate more offense. (Fans would rather watch home runs than strikeouts.) High school and college baseball teams also use a 10-inch mound.

Baseball should have lowered the mound to reduce injuries, says Dr. William Raasch. Dr. Raasch is a professor of orthopedic surgery at the Medical College of Wisconsin, and the head team physician for the Milwaukee Brewers.

Dr. Raasch and his associates recently completed a study, financed by Major League Baseball, of the stress throwing from the mound places on a pitcher's arm.

Researchers used eight digital cameras to capture the pitching motion of 20 pitchers from 10-inch, 8-inch, and 6-inch mounds, and flat ground.

"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," Dr. Raasch said.

The greater stress increases the likelihood of tearing the rotator cuff (the muscles and tendons in your shoulder that connect the upper arm bone to the shoulder blade) or labrum (a cuff of cartilage that forms a cup for the end of the arm bone to move within). These are serious injuries that require surgery and long-term rehabilitation, and often can end a pitcher's career.

The study didn't produce enough data for him to recommend that the pitcher's mound be reduced further, Dr. Raasch said. But pitchers, he said, would be better off practicing on flat ground, especially if they are recovering from an injury. Pitchers shouldn't fear that the gain in safety would be offset by a decline in performance.

Nolan Ryan was one of the greatest and most durable pitchers of all time, pitching well past the age of 40, Dr. Raasch noted.

"He liked to throw on flat ground in his waning years," Dr. Raasch said. "I think others might follow his lead."