Inning Limits Don't Prevent MLB Pitching Injuries

Waterloo, Ontario, CANADA

WATERLOO, ON--(Marketwired - April 06, 2015) - Restricting the number of innings young Major League Baseball (MLB) pitchers throw does not prevent injuries, according to new research from the University of Waterloo.

The study, published in the Journal of Sports Medicine and Physical Fitness, also found that gradually increasing the total number of innings pitched per season has no effect on young MLB pitchers' risk of future injury.

"Conventional wisdom among coaches and managers is that restricting innings for young starting pitchers, and slowly increasing the number of innings pitched over several years, gives pitchers' tissues sufficient time to adapt to the workload of a major league season," said Thomas Karakolis, lead investigator on the study. "But all our data shows that these strategies really make no difference in preventing injury."

The study looked at injury rates based on the number of innings pitched and five levels of yearly increases ranging from 10 to 50 innings. A year-over-year increase of 30 innings pitched is often used as the limit for the number of innings a young starting pitcher is allowed to pitch in any given season. The researchers found no consistent correlation between injuries and the number of innings pitched or rate of yearly increase.

"Injury is the result of workload exceeding the capacity of the body's tissues, so while counting innings is a tempting way to measure workload, it's actually a very flawed method," said Karakolis. "If coaches are looking for ways to prevent injury, simply limiting the number of innings is not the answer. They have to look at how hard a pitcher's body is working during each inning, each pitch."

The study suggests that teams need to invest in biomechanical assessments for each pitcher to more effectively prevent injuries. Alternatively, coaches and trainers can develop strength and conditioning programs that build soft tissue capacity during the offseason and promote recovery during the season. Young pitchers have greater ability for tissue adaption than their older counterparts.

Injuries have plagued the MLB in recent years, with more than 25 per cent of pitchers on the disabled list.

"The injury rate for MLB pitchers is nothing short of unacceptable," said Karakolis. "Clearly current methods for preventing injury aren't working. We need a new strategy that will keep pitchers off the disabled list for good."

The study looked at 761 independent pitcher-seasons between 2002 and 2007. All pitchers were under the age of 25 and had pitched at least one third of an inning in major league baseball.

About the University of Waterloo
In just half a century, the University of Waterloo, located at the heart of Canada's technology hub, has become one of Canada's leading comprehensive universities with 35,000 full- and part-time students in undergraduate and graduate programs. A globally focused institution, celebrated as Canada's most innovative university for 23 consecutive years, Waterloo is home to the world's largest post-secondary co-operative education program and encourages enterprising partnerships in learning, research and discovery. In the next decade, the university is committed to building a better future for Canada and the world by championing innovation and collaboration to create solutions relevant to the needs of today and tomorrow. For more information about Waterloo, please visit

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Nick Manning
University of Waterloo

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