Rest Day Requirements Have a Greater Effect on Season-Long Workload Expenditure by High School Pitchers than Pitch Count Limits: Implications for High School State Pitch Count Regulations
Authors: Manzi Joseph , Kunze Kyle , Estrada Jennifer , Dowling Brittany , Mcelheny Kathryn , Dines Joshua , Carr James 
Published: July 2021

Objectives: High school baseball pitch count limits vary widely by state; however, it is unknown how these variations impact cumulative elbow varus torque (EVT) throughout a season. Specifically, pitch count limits are a popular method for preventing overuse in youth baseball players, but rest day requirements for different pitch count limits are often highly variable and less frequently analyzed. Therefore, the objectives of the current study were to (1) investigate variations in pitch count rules across all 50 states, (2) calculate maximum game, monthly and season-long EVT across all pitch count limits, and (3) calculate EVT across all pitch count limits after adjusting for rest days required by each state. We hypothesized that the number of required rest days based on gameday pitch count limits would lead to large variations in cumulative EVT workload over the course of a season. Methods: Pitch count allowances and required rest days for high school baseball pitchers were recorded from the athletic association website of each state. The Motus Global database was queried for all high school pitchers. Average EVT for game pitches was quantified and used to calculate cumulative game, weekly, monthly, and season EVT during a projected 3-month season for each maximum pitch count limit assuming a three-day rest period. Values were subsequently recalculated for each group of states based on pitch count allowances and actual required rest days. Results: The Motus Global database provided 65,928 pitches from 45 high school pitchers with an average age of 16.9 ± 0.8 years. Average EVT per pitch was 45.04 ± 10.46 N•m. High school baseball is not a sanctioned sport in 2 states (Montana and Wyoming), leaving 48 states for analysis. The most common midseason maximum pitch count limit was 110 pitches (19 states, range 100-125 pitches), and the most common required rest days was 4 days (24 states, range 0-5 days) (Table 1). Assuming three-days rest between maximum pitch outings, there was a 20% difference in cumulative EVT during a season between 100 and 125 maximum pitches. When maximum pitch counts were projected with required rest days, allowing a maximum of 140 pitches in a 4 day span without a specific rest day requirement resulted in the most EVT during a season (Nevada), followed by allowing a maximum pitch count of 125 pitches with a rest requirement of 3 days (Louisiana/Ohio, Figure 1). Pennsylvania and Wisconsin allowed the least amount of pitches (i.e. 100 pitches) with the shortest required rest days (i.e. 3 days), resulting in the lowest EVT for a game and week but the sixth highest season EVT. Conversely, South Carolina allowed 110 pitches but required the most rest days (5 days), resulting in the lowest season EVT. Overall, there was a 48.8% difference in EVT during a season between the most and least restrictive states. A greater seasonal EVT in the lowest pitch count range with 1 required rest day compared to the highest pitch range was observed in 28 states (58%). Average seasonal workload of every pitch count range per required rest days for all states is summarized in Figure 2. This generally demonstrates an inverse trend with a 30% greater EVT differential between the lowest pitch range with one required rest day and the highest pitch range with 5 required rest days. Only 1 state had equal seasonal EVT at both maximum and minimal pitch ranges (Pennsylvania). Conclusions: There is wide variability in pitch count rules between states. Required rest days are often an underappreciated aspect of pitch count rules, yet they may influence season-long EVT more than maximum pitch count allowances. For example, the maximal seasonal EVT did not occur at maximal pitch limits for the majority of states. Instead, it most frequently occurred at the lowest pitch count allowance with 1 rest day (58% of states). A primary example is Indiana, which has a 20% greater potential seasonal EVT in the lowest pitch range (36-60 pitches, 1 rest day requirement) compared to its maximal pitch limit (101-120 pitches, 4 rest day requirement). Pitch count rules should be analyzed to ensure that projected workload across all pitch count and rest day allowances are proportional. Therefore, standardization of pitch count rules across states should be considered with increased emphasis on rest day restrictions. [Table: see text]