Abstract：This study evaluated the effects of passive muscle contraction recovery treatments, namely whole body vibration (WBV) and electromuscular stimulation (EMS) on average pitch speed, rating of perceived exertion (RPE), heart rate (HR), and blood lactate concentration of baseball pitchers during a simulated game. Nine Taiwan Division I intercollegiate baseball pitchers (starting pitchers) volunteered for this study. All pitchers received 3 recovery treatments: WBV, EMS, and control (CON) in a counter balance order. A within-subject crossover design was employed, and each experiment was separated by a 7-day interval. Pitch speed during a simulated game (pitcher performed 5 innings; 20-pitch counts per inning) was recorded. During each experiment, the pitcher received 1 of the 3 recovery treatments after each inning: WBV for 6 min (frequency: 50, 40, and 30 Hz applied for 2 min in sequences separately; amplitude: 1.5 mm), EMS for 6 min (frequency: 9, 8, and 7 Hz applied for 2 min in separate sequences), and CON (resting for 6 min). Changes in HR, RPE, and blood lactic acid (BLa) were recorded before and after recovery treatments. The results of the present study indicated that average pitch speed of WBV was significantly higher than EMS and CON. In addition, the concentrations of BLa in WBV and EMS were significantly lower than CON at post-measurement, but no significant difference between WBV and EMS. Furthermore, RPE in WBV was significantly lower than CON. The results suggest that WBV and EMS as passive muscle contraction recovery methods can decrease fatigue index (BLa levels) between innings during a simulated pitching game, but the WBV can improves pitching performance more effectively. (Full text)