Pitchers Need Limits on Innings

To prevent serious arm injuries, young baseball pitchers should pitch no more than 100 innings a year, researchers said.

In a 10-year prospective study, boys who pitched more than 100 innings were almost four times more likely to undergo elbow or shoulder surgery or to retire because of injury, according to Dr. Glenn Fleisig, of the American Sports Medicine Institute in Birmingham, Ala., and colleagues.

The cumulative rate of serious injury was 14 percent in those who exceeded that number and 4 percent in those who did not, the researchers reported in the February issue of the American Journal of Sports Medicine.

“On the basis of these findings and review of the literature, we recommend that pitchers in high school and younger pitch no more than 100 innings in competition in any calendar year,” Fleisig and his colleagues wrote.

“Young pitchers who have not developed should be limited to even less, and no pitcher should continue to pitch when fatigued.”

In recent years, researchers have detected an increase in the numbers of younger pitchers who require shoulder and elbow surgery, including ulnar collateral ligament reconstruction, or Tommy John surgery.

Many doctors believe that the trend is related to the growth of year-round baseball leagues and showcases for professional scouts, which reduces the amount of downtime pitchers would normally have in the off-season.

A 1999 study linked the number of pitches thrown to elbow and shoulder pain — assumed to be a predictor of future injury. That and similar studies led youth baseball organizations, including Little League Baseball, to replace innings limits with pitch counts.

But no studies had established a relationship between throwing volume and injury risk.

To explore the risk factors for serious arm injuries — those requiring surgery or those resulting in retirement — Fleisig and his colleagues followed 481 male pitchers ages 9 to 14 for 10 years using annual telephone interviews; about two were still pitching in the final year of the study.

The researchers focused on total innings pitched in the previous year rather than pitch counts because most youth players and their families do not keep track of the numbers of balls thrown.

During the study, three of the boys had elbow surgery, seven had shoulder surgery, and 14 retired because of a throwing injury, resulting in a 10-year rate of serious injury of 5 percent.

The average age at the time of surgery was 17, and two boys underwent surgery before they turned 13.

The only significant risk factor for serious injury was pitching more than 100 innings in a calendar year.

There was a trend toward a greater likelihood of serious injury in boys who played both pitcher and catcher during the study period (11 percent versus 4 percent), but it fell short of statistical significance because of the small sample size, according to Fleisig and his colleagues.

“A baseball player may play multiple positions, but we discourage an individual from playing both pitcher and catcher,” they wrote.