title: Impact of 12-s Rule on Performance and Muscle Damage of Baseball Pitchers.
abstract: A recent US Major League Baseball (MLB) rule change requires baseball pitchers to deliver pitches within 12 s.
  
  
  
  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.
  
  
  
  A randomized counterbalanced study.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: 1Athletic 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.
authors.forename: Sun-Chin
authors.initials: SC
authors.lastname: Yang
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Wang
authors.forename: Shin-DA
authors.initials: SD
authors.lastname: Lee
authors.forename: Y U Chung
authors.initials: YU
authors.lastname: Lee
authors.forename: Kuei-Hui
authors.initials: KH
authors.lastname: Chan
authors.forename: Yi-Liang
authors.initials: YL
authors.lastname: Chen
authors.forename: Donovan L
authors.initials: DL
authors.lastname: Fogt
authors.forename: Chia-Hua
authors.initials: CH
authors.lastname: Kuo
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D001484:Baseball / Q000293:injuries* / Q000502:physiology*; D003402:Creatine Kinase / Q000097:blood; D006801:Humans; D016753:Interleukin-10 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000293:injuries* / Q000503:physiopathology*; D063806:Myalgia / Q000209:etiology; D009220:Myositis / Q000097:blood / Q000209:etiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D015850:Interleukin-6; D016753:Interleukin-10; D003402:Creatine Kinase