Active Voice: Major League Baseball’s New Rule & Injury Risk for Pitchers

By Chia-Hua Kuo, Ph.D., FACSM

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.

Chia-Hua Kuo, Ph.D., FACSM, is a professor and researcher at the University of Taipei in Taipei, Taiwan. His research is mainly focused on muscle inflammation under exercise challenges and its role in metabolic aging.

This commentary presents Dr. Kuo’s views on the topic related to a research article that he and his colleagues authored. Their research article appears in the December 2016 issue of
Medicine & Science in Sports & Exercise® (MSSE).

Between the years 2004 and 2014, the average length of Major League Baseball (MLB) games in the U.S. increased by more than 25 minutes. Recently, MLB made a rule modification to cut down the length of time between pitches — requiring the interval to be shortened from 20 to 12 seconds! This new policy, within one year, decreased the time of an average game from three hours and eight minutes (in 2014) to two hours and 56 minutes.

The downside of the rule modification is that the between-pitch recovery time for pitchers now is shortened by roughly 40 percent. While the rule doesn’t directly affect the overall pitcher throwing load during a game, cumulative throwing fatigue of pitchers could result due to insufficient recovery. It is imperative to establish the scientific basis for this rule change so that policymakers can include consideration of implications for musculoskeletal health of the pitchers. Thus, we designed a counter-balanced crossover study to evaluate the impact of increasing pitching pace on pitchers’ performance and muscle damage during and 72 hours after a simulated seven-inning game. Our findings, published in the December 2016 issue of MSSE, show early onset of fatigue during the game, followed by protracted elevations in muscle damage (plasma creatine kinase) and inflammation markers. We compared effects in the simulated game setting using three different rest intervals between pitches: eight, twelve or 20 seconds. There were negligible increases in these adverse markers when pitchers rested for 20 seconds between pitches, in compliance to the original rule. This result suggests that about 20 seconds of recovery time between pitches is safe for pitchers. However, when recovery time was limited to 12 seconds between pitches, we found that the post-game muscle damage and inflammation persisted for a longer time.

Fatigue, muscle damage and inflammation can substantially weaken proprioception, joint stability and kinematics of pitchers. Thus, this new rule might increase the risk of more severe overuse-type injury throughout a pitcher’s career. With high pitching pace, early replacement by relief pitchers during a game or providing a longer recovery time for pitchers after a game may be needed to protect pitchers from accumulated muscle damage, as well as preserve their potential for maintaining performance and contributing to the success of the team.

MLB is the world leader in professional baseball due to its large market size. This rule change may soon have a global ramification to rule makers from other professional baseball institutions. Given that pitchers are valuable assets in baseball at any level, we recommend that MLB reconsider the rule modification in concern for pitchers’ musculoskeletal health and professional longevity.