Major League Baseball pace-of-play rules and their influence on predicted muscle fatigue during simulated baseball games

ABSTRACT

Major League Baseball (MLB) has proposed rule changes to speed up baseball games. Reducing the time between pitches may impair recovery from fatigue. Fatigue is a known precursor to injury and may jeopardise joint stability. This study examined how fatigue accumulated during baseball games and how different pace of play initiatives may influence fatigue. Pitcher data were retrieved from a public database. A predictive model of muscle fatigue estimated muscle fatigue in 8 arm muscles. A self-selected pace (22.7 s), 12 s pace (Rule 8.04 from the MLB) and a 20 s rest (a pitch clock examined in the 2014 Arizona Fall League (AFL)) were examined. Significantly more muscle fatigue existed in both the AFL and Rule 8.04 conditions, when compared to the self-selected pace condition (5.01 ± 1.73%, 3.95 ± 1.20% and 3.70 ± 1.10% MVC force lost, respectively). Elevated levels of muscle fatigue are predicted in the flexor–pronator mass, which is responsible for providing elbow stability. Reduced effectiveness of the flexor–pronator mass may reduce the active contributions to joint rotational stiffness, increasing strain on the ulnar collateral ligament (UCL) and possibly increasing injury risk.

KEYWORDS:

• Muscle fatigue
• baseball
• injury prevention

Acknowledgements

Thanks to Dr Jim Lyons, Dr Jim Potvin and Daanish Mulla for their feedback in the preparation of this manuscript. Thanks to the anonymous reviewers of this manuscript for their valuable contributions.

Disclosure statement

No potential conflict of interest was reported by the authors.