Jo Jan 23, 2024

Barbell’s trajectory and other kinematic properties such as velocity and acceleration are the most important parameters for weightlifting technique, so they have been investigated by several researchers.

Because weightlifter’s bad motion could cause certain variation in barbell trajectory, studies on optimizing the barbell trajectory have been conducted.

Some optimization algorithms including genetic algorithm and optimal control theory were applied to optimization of barbell trajectory during snatch lift with optimization parameters defined as the sum of actuating torques of all joints. What is more, previous works were limited to 5 segments without considering the head of a lifter’s model and to adoption of statistical data for physical properties of human body.

Jon Min Hyok, a researcher at the Faculty of Shipbuilding and Ocean Engineering, has developed a kinematic model of 6 segments and proposed a method for optimization of barbell’s trajectory based on the kinematic model.

The six segments are shin, thigh, trunk, upper arm, forearm and head which accounts for about 10 percent of body weight and is considered as one segment of one degree of freedom. He obtained the physical properties of the model such as mass, barycenter and inertia moment of every part of body from anthropometry, not statistical data, which were used to make a model by Solidworks and calculated. In addition, for optimization of barbell trajectory, he formulated an optimal control problem so that the actuating torques of joints are minimized and solved it by Pontryagin Maximum Principle (PMP).

The results obtained by the proposed method are in good agreement with ones given by analysis of lifter’s actual performances, so it will give help with weightlifting training.