Assessment of some characteristics of the motor actions of the exercise “pushing two weights in a long cycle” based on biomechanical control

Relevance. Kettlebell lifting is a relatively new sport that has not been extensively studied. However, a long-term analysis of official national and international competition records indicates a steady increase in the number of participants and improvement in athletic performance across all weight categories. Analysis of scientific literature on kettlebell lifting, particularly the exercise «pushing two kettlebells in a long cycle», reveals a limited number of studies on this topic. The kinematic features of motor actions during various stages of a competitive lift have not been well-researched, which highlights the importance of further investigation. The aim of the study was to evaluate the kinematic characteristics of the knee joint flexion angle during a pushing two-weight exercise in a long cycle, to compare angle values in key phases of the cycle among athletes of different levels of athletic fitness and weight categories, and to assess angle dynamics as fatigue accumulates during competitive performance. Methods. 132 athletes (average age 24.6 ± 3.8 years; training experience 7.2 ± 2.9 years) were examined. To conduct the study, we used methods of biomechanical analysis of motor actions, including video recording of competitive exercises during official competitions and subsequent analysis of the video using the KINOVEA program. We analyzed the angles of knee joint flexion in all 10 motor phases of the cycle. For each athlete, we processed five full cycles. The systematic error of the method was 0.5 degrees. Results. Based on the findings of the study, the phase composition of the exercise was identified, and the angles of knee joint bending in various motor phases were analyzed. Statistically significant differences were found in the values of knee joint flexion angle during the squat phase among athletes of different fitness levels (H=18.7; p<0.001) and weight categories (H=12.8; p<0.01). The dynamics of increasing squat depth as fatigue develops towards the end of competition time (p<0.05) was also revealed. Footwork is crucial for the performance of competitive exercises, and the values of bending angles of knee joints determine the rationality of technique for its execution. During the squat phase, the angle of knee bending can range from 110°–130°, depending on the weight and speed characteristics of the athlete. Upon standing, the legs are straightened, forming an angle of 170°–180°. This provides short-term relaxation for the thigh muscles. The angle of flexion at the knee joints changes dynamically, with multiple repetitions occurring. Excessive bending of the knees or insufficient straightening of the legs during the squatting phase can increase the energy cost of lifting weights. Conclusion. The analysis of kinematic characteristics such as the angle of knee flexion and the time it takes to change the angle shows that they are informative indicators and can be used as markers for biomechanical control in athletic training. These quantitative patterns can be used to automatically recognize movement phases and classify technical errors, which can help in the development of automated training support systems.