Lower extremity plyometric training reduces elbow varus torque and increases ball velocity in adolescent baseball pitchers.

OBJECTIVES

This study examined the effects of lower-extremity plyometric training and balance training on pitching-related kinetics, performance, and lower-extremity function in adolescent baseball pitchers.

DESIGN

Cluster-randomized controlled trial.

METHODS

Sixty adolescent baseball pitchers were allocated to a plyometric training group, balance training group, or control group and completed a six-week intervention. Primary outcomes were elbow varus torque, ball velocity, and arm speed during pitching. Secondary outcomes included dynamic and static balance and lower-extremity power assessed using a countermovement jump.

RESULTS

Elbow varus torque demonstrated a significant Group × Time interaction and decreased significantly only in the plyometric training group (-12.8 N·m; ~23%), whereas no significant changes were observed in the balance training group or control group. Ball velocity increased in both intervention groups (plyometric training group: +4.2 km/h; balance training group: +2.6 km/h), with no changes in arm speed across groups. Countermovement jump-derived concentric-phase lower-extremity power improved only in the plyometric training group, reflected by significant increases in propulsive force, propulsive impulse, and jump height. Dynamic balance improved in both intervention groups, whereas static balance improved significantly only in the balance training group; no meaningful changes were observed in the control group.

CONCLUSIONS

These findings indicate that lower-extremity plyometric training enhances throwing performance while attenuating elbow loading, potentially through combined improvements in lower-extremity force-generating capacity and postural control. Therefore, lower-extremity plyometric training may represent an effective strategy for enhancing throwing performance while mitigating mechanical stress at the elbow in adolescent baseball pitchers.