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AAOS Now

Published 4/1/2011
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Lisa Weisenberger

Limiting the pitch count for young athletes

For years, sports medicine professionals have been concerned about youth pitching injuries and the stress the motion causes on developing bones and muscles. According to the results of “Risk of Serious Injury for Young Baseball Players: A 10-Year Prospective Study,” those concerns are valid. The study, published in the March 2011 issue of The American Journal of Sports Medicine, found that participants who pitched more than 100 innings in a year were 3.5 times more likely to be injured.

“The study proved a direct link between innings pitched in youth and adolescent baseball and serious pitching injuries,” said lead researcher, Glenn S. Fleisig, PhD, of the American Sports Medicine Institute in Birmingham, Ala. The study followed 481 healthy male pitchers, aged 9 to 14 years, from 1999–2008. Each participant was interviewed annually about his baseball activity over the previous 12 months: what positions he played, how many innings he pitched, what types of pitches he threw, what teams (spring, summer, fall, winter) he played on, and if he participated in baseball showcases. Each player was also asked if he had an elbow or shoulder injury that led to surgery or retirement from baseball.

Of the 481 participants, 29 pitched 100 or more innings during a single year, and 4 of them (14 percent) sustained an injury that led to surgery or retirement from the sport. Among the 452 players who pitched fewer than 100 innings a year, 20 (4 percent) sustained such an injury.

During the 10-year span, 5 percent of the entire cohort sustained a serious injury resulting in surgery or retirement. Three participants had elbow surgery and seven had shoulder surgery. Two of the boys in the study had surgery before their 13th birthday. In addition, 14 boys retired due to a throwing injury. Only 2.2 percent were still pitching by the 10th year of the study.

“It is a tough balancing act for adults to give their young athletes as much opportunity as possible to develop skills and strength without exposing them to increased risk of overuse injury,” said Dr. Fleisig. “Based on this study, we recommend that pitchers in high school and younger pitch no more than 100 innings in competition in any calendar year. Some pitchers need to be limited even more, because no pitcher should continue to pitch when fatigued.”

The study also looked at the trend of playing pitcher and catcher in the same game, which did appear to double or triple a player’s risk of injury, but the trend was not statistically significant. The study also could not determine whether starting to pitch curveballs before age 13 increased the risk of injury.

“This study highlights the need for parents and coaches to monitor the amount of pitching for the long-term success and health of these young athletes,” said Dr. Fleisigo. “Education through campaigns like STOP Sports Injuries is an excellent first step.”

More information about STOP (Sports Trauma and Overuse Prevention) can be found at www.stopsportsinjuries.org

Dr. Fleisig’s coauthors for “Risk of Serious Injury for Young Baseball Pitchers: A 10-Year Prospective Study” (Am J Sports Med 2011;39:253) are James R. Andrews, MD; Gary R. Cutter, PhD; Adam Weber, BS; Jeremy Loftice, BS; Chris McMichael, MPH; Nina Hassell, MPH; and Stephen Lyman, PhD. The first year of this study was funded by a grant from USA Baseball.

Disclosure information: Dr. Andrews—Biomet Sports Medicine; Biomet; Bauerfiend; Theralase; MiMedx; Physiotherapy Associates; Patient Connection; Connective Orthopaedics; FastHealth Corporation; AOSSM; Physiotherapy Associates; Dr. Lyman—International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine; American Journal of Orthopedics; Dr. Fleisig—American Journal of Orthopedics; the other authors report no disclosures.

Lisa Weisenberger is director of communications for the AOSSM. She can be reached at lisa@aossm.org

Additional Resource:
Risk of Serious Injury for Young Baseball Pitchers

Bottom line

  • This prospective cohort study showed a cumulative incidence of injury of 5 percent during a 10-year period for boys who start pitching at the youth level.
  • Players who pitched more than 100 innings in at least one calendar year had 3.5 times as much chance of serious injury as those who pitched fewer than 100 innings.
  • The study’s limitations include small sample size, limited geographic coverage area, and narrow definition of injury, to the exclusion of other potential risk factors.