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

Peak Horizontal Ground Reaction Forces and Impulse Correlate with Segmental Energy Flow in Youth Baseball Pitchers

The purpose of this study was to determine associations between horizontal ground reaction force (GRF) kinetics and energy flow (EF) variables in youth baseball players. Twenty-four youth baseball players pitched fastballs in an indoor laboratory while motion capture and force plate data were collected. Horizontal GRF variables were extracted (peak GRF and GRF impulse) while EF was calculated by integrating magnitudes of mechanical powers transferred into and out of the pelvis, trunk, and arm segments via joint force power (JFP) and joint moment power (JMP) components. Peak propulsive GRF of the drive (back) leg correlated with EF into proximal segments, whereas peak braking GRF of the stride (lead) leg correlated with EF into distal segments. Furthermore, peak GRF of the drive leg and GRF impulse of both legs correlated with the JFP components of EF into the pelvis and trunk segments. In contrast, peak GRF and GRF impulse of the stride leg both correlated with the JMP components of EF into the arm segment. These results suggest that horizontal GRF impulse from the drive and stride leg contribute to EF between major segments of the lower and upper extremity. In addition, these results also suggest that propulsion kinetics of the drive leg play a role in transferring linear power via the pelvis and trunk segments in the throwing direction of the pitch, whereas braking kinetics of the stride leg play a role in creating rotational power that is transferred between the trunk and arm segment via the shoulder joint