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213 Development of a protocol to evaluate baseball pitcher’s workload and prevention of injury
  1. Jason L Zaremski,
  2. Pazik N Marrisa,
  3. Horodyski MaryBeth
  1. University of Florida, Gainesville, Florida, USA


Background Pitch counts are one measure of workload in baseball. Newer research indicates pitch counts underestimate true total workload. Thus, current monitoring systems gauging throwing injury threshold may be considered inadequate.

Objective Develop a novel technique to determine workload in baseball pitchers to provide an implementable method for prevention of throwing related injuries.

Design Prospective observational study

Setting Academic medical center and community baseball fields.

Participants Pitchers aged 13–18 from the 2019 to 2021 seasons.

Assessment of Risk Factors The independent variable was innings pitched, grouped by 1–2 innings, 3–4 innings, 5–6 innings, and 7 innings.

Main Outcome Measurements Workload percent, calculated by multiplying volume of total gameday pitches by intensity, was the primary measure. Intensity was determined by maximum pre-season velocity compared to game velocity of pitches thrown. Velocity was measured during a preseason practice and the first 10 pitches of each inning. Total gameday pitches included bullpen, warm-up, and game pitches.

Results 147 total pitcher outings, 42 total pitchers, 4 pitching related injuries. Total game pitch counts ranged from 17 to 219 (mean 78.8, SD 38.7). Velocity ranged from 74.4 to 136.5 km/hour. Intensity ranged from 0.68 to 1.26 with a mean of 1.0 (SD 0.09). ANOVA was completed with significant differences noted for total pitches (p<0.001) and workload percent (p<0.001). Post hoc analyses for total pitches and workload percent resulted in significant differences (p<0.001) between all inning groupings except innings 5–6 compared to inning 7.

Conclusions Our workload model indicated that workload and pitch counts are associated. As we gather more data (2022 season), if workload and injuries are significantly associated, then by extension total gameday pitch count would become a correlate to workload and injuries. Workload monitoring using our system may lead to prevention of injuries in baseball pitchers.

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