How pitching changes little leaguers'...( At this year's Little League World S...),Health

At this year's Little League World Series, new rules for the first time forced players to limit the number of times pitchers could throw the ball, and coaches had to strategize how pitchers were used more carefully.

Under the old system, a pitcher age 12 and under could throw up to six innings per week and six innings per game. But in response to an increase in reported cases of young pitchers experiencing arm and shoulder problems, this year the Little League instituted pitch limits rather than innings limits, and required specific rest periods when a pitcher reached the threshold of pitches delivered in a day. Under the new rules, anyone who throws more than 20 pitches in a day needs to rest a day before he can pitch again. If pitchers throw 85 pitches in a day, they must rest at least three days before pitching again.

When Dr. Scott Mair and colleagues at the University of Kentucky began research into what throwing really does to young arms and shoulders seven years ago, they had many questions about those physical changes since most research until then had focused only on adult players. Now that their research is complete, Mair has those answers, along with one surprising finding.

To evaluate these adaptive changes, the study followed 32 male baseball players between 13 and 21 years of age for six years to study changes in the shoulder's range of motion and strength, along with any growth plate changes shown by X-ray images.

What the researchers found was that repeated pitching does cause changes in the upper arm bone and soft tissue in the shoulders of young baseball players, but that these types of changes generally help protect players from injury, so it's not necessarily a bad thing. Mair said these changes may actually allow for better throwing velocity and less injuries to the shoulder.

"However," he cautioned, "pitching too much and playing year-round can push those adaptive changes to the point of injury
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