Biomechanical coordination during counter–movement jump with grasping dumbells

Abstract

The aim of this study was to investigate how grasping dumbbells during a countermovement jump (CMJ) affects kinematic variables like jumping height and arms swinging motion, and kinetic variables like ground reaction force and joint torque components in the lower and upper extremities. Twelve male students participated in this study and performed CMJ with and without grasping dumbbells for 0kg, 1kg, 2kg, 3kg, and 4kg. We captured their CMJ movement using a high-speed camera (300fps) and ground reaction force during CMJ using a force platform (1000Hz). Then, segment and joint angles and torque components in the lower and upper extremities. We found that while no significant changes in jumping height and joint torque in the lower extremity between each dumbbell condition were obtained, significant decreases in the angle at the toe-off, angular displacement during the arm swing phase in the shoulder joint, and some torque components as muscle and Coriolis torques in the shoulder and elbow joints as dumbbell mass increased. On the other hand, contact duration and the impulse of vertical ground reaction force during the ascent phase of jumping were increased. The findings indicate that the shoulder joint responded to the changes in the mass of the dumbbell by decreasing angular displacement and torque components such as muscular and Coriolis torques. If subjects continued CMJ with grasping dumbbells, muscle and Coriolis torques about the shoulder joint would be enhanced, and jumping height would increase.