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 Four male collegiate Division I baseball players from China (age: 18.5 ± 0.58 years, height: 181.00 ± 6.83 cm, weight: 78.00 ± 5.48 kg) participated in this study. 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 Kruskal-Wallis non-parametric 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 % (p0.05). Stepwise multiple regression indicated that pitching speed was influenced by Max PL, with the equation: mph = 78.816 + 7.001 Max PL, R2 = 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.