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Impact of 12-s Rule on Performance and Muscle Damage of Baseball Pitchers
Sun-Chin Yang1, Chia-Chi Wang, Shin-DA Lee
11Athletic Department, Shih Hsin University Taipei, TAIWAN; 2Graduate Institute of Athletics and Coaching Science, National Taiwan Sport University, Tao Yuan County, TAIWAN; 3Athletic Department, National Taipei University of Business, Taipei, TAIWAN; 4Department of Physical Therapy and Graduate Institute of Rehabilitation Science, China Medical University, TAIWAN; 5Department of Occupational Therapy, Asia University, Taichung, TAIWAN; 6Athletic Department, Vanung University, Taoyuan, TAIWAN; 7Department of Sports Sciences, University of Taipei, Taipei, TAIWAN; and 8Department of Kinesiology, Health, and Nutrition, The University of Texas at San Antonio, San Antonio, TX.
Introduction:
A recent US Major League Baseball (MLB) rule change requires baseball pitchers to deliver pitches within 12 s.
Purposes:
To examine the effect of three between-pitch rest intervals on throwing performance during a simulated seven-inning game and muscle damage during postgame recovery.
Design:
A randomized counterbalanced study.
Methods:
Seven intercollegiate pitchers threw 15 pitches per inning for seven innings with rest interval trials of 8, 12, and 20 s between pitches and 5 min between innings. Pitchers threw aimed fastballs at their best effort. Trials were separated by ≥2 wk.
Results:
Progressive decreases in pitching speed and accuracy below baseline (first inning of 20-s trial) occurred after fourth inning during the 8-s and 12-s trials, but not the 20-s trial. Plasma creatine kinase elevated 48 h later for the 8-s and 12-s trials (+105% and +75%, P < 0.01), but not the 20-s trial (+26%, no significance). A transient interleukin (IL)-6 surges immediately after the game for the 8- and 12-s trials (+265%, +128%, P < 0.01) above baseline. IL-6 reversed below the level of 20-s trial at 48 h after game, whereas IL-10 increased significantly above the level of 20-s trial.
Conclusions:
Under the same pitching load, decreasing rest interval from 20 to 12 s or less results in an early-onset performance loss during a game and increases in muscle damage and inflammation for more than 2 d after a game. Our data do not favor the current rule change in concern of keeping musculoskeletal health of pitchers.
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