Energy Flow Analysis to Investigate Youth Pitching Velocity and Efficiency.

Purpose: The purposes of this study were 1) to investigate the transfer of energy through the kinetic chain by youth baseball pitchers during the pitching motion and 2) to provide insight into how the total magnitude of energy flow and its linear and rotational components relate to both velocity and joint torque per unit increment of pitch velocity (joint load efficiency).

Methods: Twenty-four youth baseball pitchers participated in this study. Data collection occurred in an indoor research laboratory equipped with a 14-camera infrared motion capture system and an instrumented pitcher's mound with embedded force plates. Energy flow was calculated by integrating power transfer into and out of each segment. The magnitudes of key instances of energy flow were compared to pitch velocity and velocity-normalized joint torques using simple linear regressions.

Results: All of the energy flow variables calculated had a significant correlation to pitch velocity. Energy flow into the arm from the trunk had the strongest correlation to velocity of any variable investigated (r = 0.900, P = 0.000). The total magnitude of energy flow into the trunk had a significant correlation to increased horizontal shoulder adduction efficiency and shoulder internal rotation efficiency. The magnitude of energy flow into the trunk by only joint forces had a significant correlation to increased horizontal shoulder adduction efficiency, shoulder internal rotation efficiency, and elbow varus efficiency.

Conclusions: Energy flow analysis is an effective tool providing quantitative assessment of the kinetic chain to gain a deeper understanding of how energy moves through an athlete, and how specific pitching mechanics impact this movement. The results of this study support the importance of generating energy flow throughout the body to produce high velocities and energy flow through the trunk to increase pitch efficiency.