Monitoring pitching load and lower-limb fatigue in collegiate baseball: A simulated-game comparison across competitive levels

This study examined whether baseball pitchers at different competitive levels exhibit distinct fatigue patterns in ball speed and lower-limb neuromuscular function during a prolonged simulated game. Twenty right-handed collegiate pitchers (ten Division I, ten Division II) completed a seven-inning simulated game, throwing 15 fastballs per inning. Ball speed was recorded for every pitch, and countermovement jump (CMJ) and rating of perceived exertion (RPE) were assessed pre-game and between innings. A mixed-design ANOVA (Group × Inning) was used to analyze ball speed, CMJ variables, and RPE. Ball speed showed a significant Group × Inning interaction ( p = .04): Division I pitchers displayed only a small, non-significant decline across innings (Δ = −2.88%), whereas Division II pitchers demonstrated a significant reduction beginning in the third inning (Δ = −5.73%). In contrast, key CMJ mechanical variables showed significant main effects of Inning, with similar declines in both groups, and RPE increased progressively. These findings indicate that extended pitching induces comparable lower-limb neuromuscular fatigue across competitive levels, but only lower-level pitchers express this fatigue as an early decline in ball speed. CMJ may therefore serve as a sensitive, objective tool to complement ball speed when monitoring fatigue and managing pitching workload.