Differences in external loads of different pitch types in Chinese male college baseball players.

Background: In baseball, monitoring player load solely through pitch count and innings overlooks the variability introduced by different pitch types. This study analyzed differences in external load, measured as Player Load, across various pitch types using a GPS-based wearable device. Additionally, the relationship between Player Load and ball velocity was examined. Methods: Data from 320 baseball pitches were collected for experimental analysis. External loads were collected for four pitch types, fastball, changeup, curveball, and slider, using a wearable sensor device that recorded six variables: Maximum Player Load (Max PL), Maximum Rotation (Max Rot), Pitching Hourly Velocity, and Percentage of Acceleration Change in the Three Axes (Up Load %, Side Load %, and Fwd Load %). A one-way ANOVA test was used to assess differences across pitch types, while stepwise multiple regression analyzed the impact of Player Load on pitching speed. Results: Significant differences were observed among pitch types for Max PL, Max Rot, Hourly Speed, Up Load %, and Fwd Load % (p < 0.05), while Side Load % did not show a significant difference (p > 0.05). Stepwise multiple regression indicated that pitching speed was influenced by Max PL, with the equation: mph = 78.816 + 7.001 Max PL, R 2 = 0.192, suggesting that Max PL accounted for 19.2% of the variability in pitching speed. Discussion: External training loads in pitching vary by pitch type, with variable-speed pitches generating higher peak external loads, whereas fastballs are associated with greater ball speeds.