Evaluating Segmental Contribution To Whole-body Center Of Mass Movement In Sub-maximal Overhand Throwing.

Abstract

Recent advancements in wearable technology have allowed kinematic data collection in field-based settings, improving the ecological validity of research investigations. The wrench notation and quaternion algebra inverse dynamics technique does not require the integration of force platform data, therefore may allow field-based computation of joint kinetics for various sport movements, including overhand throwing. In order to apply this technique efficiently, it is important to understand segmental contributions to whole-body center of mass (CoM) movement. PURPOSE: Evaluate segmental contribution to the estimation of whole-body CoM movement both proximal and distal to the throwing elbow. METHODS: Three right-handed, male club baseball players performed forty trials of sub-maximal overhand throwing. Position data for each trial were acquired using a 3-d optical motion capture system and infrared reflective markers placed according to standard body segment parameter recommendations. From position data, segmental and whole-body CoM were computed for body mass positioned proximal and distal to the throwing elbow. Root Mean Squared Error (RMSE) values were computed using time-series position data between each segment CoM and whole-body CoM. Two one-way ANOVAs were performed on RMSE values in the x (direction of throw), y (perpendicular to the throw), and z (vertical) directions. To evaluate the movement of mass proximal to the throwing elbow, twelve body segments were included as levels within a single segment factor. To evaluate the movement of mass distal to the throwing elbow, two segments were included as levels within a single segment factor. RESULTS: Main effects of segment were observed for RMSE in the x, y, and z directions (p = < 0.001 - 0.001). Trunk RMSE in the x, y, and z directions (x: 40.5 ± 7.4 mm, y: 28.9 ± 5.2 mm, z: 9.5 ± 4.0 mm) was significantly lower versus all other segments proximal to the throwing elbow (p = < 0.001 - 0.028). Right forearm RMSE in the x, y, and z directions (x: 28.9 ± 3.3 mm, y: 22.6 ± 2.3 mm, z: 31.7 ± 1.0 mm) was significantly lower versus the right hand (p = < 0.001 - 0.001). CONCLUSION: During an overhand throwing task, the results suggest that CoM movement of the trunk and throwing forearm pattern closely with the movement of whole-body CoM located proximal and distal to the throwing elbow.