Dynamics of muscle electric activity parameters and maximum power characteristics in different phases of performance of weightlifting snatch

Weightlifting exercises are coordinately complex, speed and power based movements, which simultaneously combine the maximum muscle work with different contraction types and limit the result with special functional features of the neuromuscular apparatus. According to modern views, indicators of biomechanics of the motor act and electromyographic characteristics of leading muscles during performance of the act show different aspects of the same process of contraction and can be used as criteria for an evaluation of muscle efforts and the functional state of the neuromuscular apparatus. The objective of this study is to identify special features of dynamics of muscle electric activity parameters and maximum power characteristics in different phases of weightlifting snatch. The study involved 35 male elite weightlifters with the Master of Sports qualification. The study was conducted with the BTS Motion System (made by BTS Bioengineering, Italy). A computer program was developed to analyze the technique of the snatch (the certificate RU 2020660142 from 28.08.2020). The study included registration and following analysis of biomechanical (dynamic, kinematic) and electromyographic indicators during performance of the snatch by athletes with 80% intensity of the maximum weight directly during the training session. Features of dynamics of muscles’ electric activity parameters and maximum power characteristics, which are significantly changing in different phases of performance of the snatch, were revealed in the study. Pull phases are characterized by the increase of muscle tension, muscle work in the concentric dynamic contraction. Snatch phases are characterized by the maximum power of muscle tension and the speed of its dynamics according to both biomechanical features and electrical processes in muscles: a maximum tension and high frequency of impulsion of motor units of extensor muscles were noted. Squat phases are characterized by the decrease of muscle tension and speed of its changing, muscle work in the combined type of contraction, including eccentric and static types. High, but not maximum indicators of power and tension of muscles characterize phases of standing-up. It was revealed that the eccentric muscle contraption, according to EMG indicators, is manifested in the decrease of both amplitude and frequency characteristics. The concluded study allowed to present data characterizing biomechanics of the motor act and special physiological features of leading muscles’ work of elite weightlifters during performance of the exercise. Power and electromyographic parameters in various types of muscle work in different phases of the snatch were determined.