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Youth Baseball Pitching Study Shows Overuse is Primary Cause of Arm Injuries

No Proof Curve Balls are More Dangerous than Other Pitches

A five-year study, recently concluded by the Department of Exercise and Sport Science at the University of North Carolina, found that the primary cause of arm injuries in youth baseball players was overuse. It also failed to show an increased risk of arm injury due to breaking pitches, such as curve balls.

“Some within the baseball community have advocated for a ban on curveballs,” Stephen D. Keener, President and Chief Executive Officer for Little League Baseball and Softball, said. “However, the study conclusions do not clearly support such a ban.

“Furthermore, a ban on breaking balls would not be simple to put into practice,” Mr. Keener said. “With such a wide range of aptitude and ability, it’s practically impossible to judge if any youth pitcher intended to throw a curveball or if that’s just how the ball came out of the pitcher’s hand. To task our dedicated volunteers with judging the type of pitch thrown is not only unfair, it would be impractical.”

Little League Baseball and Softball, the largest youth sports organization in the world, in collaboration with USA Baseball, the governing body of amateur baseball in the United States, and the Department of Exercise and Sport Science at the University of North Carolina in Chapel Hill, conducted the study of pitching arm injuries in youth baseball.

Funding for the five-year study, which begin in 2006, was provided through a grant from the Yawkey Foundations.

“We are proud to support this study and recognize the need to further our understanding of the causes of arm injuries in youth baseball and the importance of protecting the health and wellbeing of its players,” James Healey, President of the Yawkey Foundations, said. “Little League’s ability to provide healthy opportunities for youth is important to the future of the sport and the Yawkey Foundations are pleased to be involved.”

The aim of the study, the first substantive research done in this area, was to describe the incidence and prevalence of pitching arm injuries and examine the risk factors.

The study used three different test groups – Little League pitchers (ages 8-13); high school-aged pitchers; and college-aged pitchers. The Little League test group consisted of 410 players who were followed for four years between 2006 and 2010. The test group from the high school level was made up of 293 players who were recruited in 2007 and followed for additional years. The college test group consisted of 629 players that were followed for two years beginning in 2008.

The pitchers were surveyed each year to assess their pitching methods, techniques, pain presence and injury occurrence. The factors acquired from the surveys were then analyzed to assess which of those factors influenced pitching injury risk.

The study produced several findings including the following:

  1. The relationship between age, type of pitch and injury risk is complex, but there was no clear evidence that throwing breaking pitches at an early age was an injury risk factor; and;
  2. The data showed the primary cause of arm injuries is overuse, not the type of pitch.

The study’s principal investigators were: Frederick O. Mueller, Ph.D., Dept. of Exercise and Sport Science, University of North Carolina; Stephen W. Marshall, Ph.D., Department of Epidemiology, University of North Carolina; and the late Dr. Barry Goldberg, a former member of the Little League International Board of Directors, and Director of Sports Medicine for Yale University’s Health Services, who championed this study.

In 2008, Little League Baseball became the first national youth baseball organization to adopt the pitch count, instead of the number of innings pitched, as the basis for its pitching rules.

“Even if Little League were to find a practical way to ban curveballs in our program, they would remain a part of the game for children playing outside our program, as they have been for decades,” Mr. Keener, a Little League graduate, said. “For coaches and parents, armed with the information in this report, the decision on when and how to teach the curveball is a matter of preference and education.”

Little League has relied on the expert advice and counsel of Dr. James Andrews, Founder and Medical Director of the American Sports Medicine Institute (ASMI); and Dr. Glenn Fleisig, Research Director at ASMI for the development of its groundbreaking pitch count rules. Dr. Andrews, who currently serves on the Little League International Board of Directors, and Dr. Fleisig are two of the world’s most knowledgeable and respected authorities on pitching injuries.