'Windmill' pitch a risk to softball pitchers' arms
NEW YORK (Reuters Health) - The "windmill" motion used in fast-pitch softball puts pitchers at risk for injuries to the biceps muscle, a new study suggests.
Softball pitching has traditionally been seen as less stressful to the arm than the overhand pitching used in baseball. However, recent studies have suggested that college and professional softball pitchers run a high risk of chronic shoulder pain.
The new study, published in the American Journal of Sports Medicine, suggests that strain placed on the biceps muscle, which connects with tendons in the shoulder, may be to blame.
"The conventional belief has been that the underhand throwing motion of softball places little stress on the arm," senior researcher Dr. Nikhil Verma, a sports medicine specialist at Rush University in Chicago, said in a written statement. "But that is not the case."
Understanding how pitchers' shoulder pain originates may help doctors and trainers develop better ways of preventing and treating it, according to Verma and his colleagues.
For their study, the researchers analyzed the pitching motions of seven college and professional softball players. They used a technique called surface electromyography, which uses electrodes placed on the skin, to collect information on muscle firing patterns during each pitch.
The women perform both standard windmill pitches -- where the arm whips in a full circle ending with an underhand pitch to the plate -- and overhand pitches like those used in baseball.
Verma's team found that compared with the overhand pitch, the windmill variety produced a much greater force in the biceps. The muscle was maximally contracted as the pitcher's arm swooped downward, just before releasing the ball.
"The greatest impact is on the biceps, as the muscle first accelerates the arm and then puts on the brakes, after transferring force to the ball," Verma explained.
The findings help explain why shoulder pain -- and, in particular, pain in the front of the shoulder -- is so common in softball pitchers, according to the researchers.
"This study helps explain the etiology of that shoulder pain," Verma said, "and may help doctors devise better treatment and prevention strategies."
SOURCE: American Journal of Sports Medicine, March 2009.
