BIOMECHANICAL ANALYSIS OF THE PUSH IN FEMALE WEIGHTLIFTERS OF DIFFERENT LEVELS OF FITNESS

Abstract

Introduction. Technical efficiency of the clean and jerk in women’s weightlifting is largely determined by controlling the position of the torso in the sagittal plane during the phases of “failure”, “push-out”, fixation and support of the barbell. Purpose was to determine changes in the angles of inclination of the torso during the performance of the competitive clean and jerk exercise in weightlifters depending on the level of physical fitness in conditions of many years of training. Methods. The study involved 64 female athletes of the first group of weight categories (up to 53 kg), who during four stages (12, 14, 17, 20 years) underwent the educational and training process in sports and youth schools of the cities of Kharkiv and Romny. Biomechanical analysis was carried out by video recording with subsequent frameby- frame processing in Dartfish; the angle of inclination of the torso relative to the horizontal was estimated in ten phases of the clean and jerk with a load of 80% of the maximum lifted weight. Each athlete performed a series of ten repetitions in the recovery state, statistical processing was performed using parametric methods (normality test and Student’s t-test). Results. The results showed a pronounced positive dynamics of angular characteristics with the transition from the junior to the experienced stages. In particular, an increase in the trunk angle was recorded in the starting phases of the pull: F1 – 12,3±1,53° – 25,2±1,58° (t1,4=5,87; p<0,001), F2 – 35,0±3,65° – 68,7±4,73° (t1,4=5,64; p<0,001), while decreases were found in the phases of the second pull and final acceleration: F3 – 94,7±2,65° – 79,8±2,73° (t1,4=3,92; p<0,001), F4 – 105,4±4,89° – 73,8±3,34° (t1,4=5,34; p<0,001). In the “push-out” there was also a decrease in angles: F7 – 92,6±1,08° – 84,7±1,01° (t1,4=5,34; p<0,001), F8 – 79,1±0,34° – 77,3±0,29° (t1,4=3,97; p<0,001), F9 - 90,3±0,86° – 85,0±0,84° (t1,4=4,41; p<0,001), whereas in the final straightening phase an increase was noted: F10 – 82,2±0,85° – 87,6±0,88° (t1,4=4,41; p<0,001). Separately, an increase in the angle during active braking before the push-out was established: F6 – 72,1±0,81° – 77,1±0,79° (t1,4=5,39; p<0,001). In athletes of group IV (stage of preparation for higher achievements), a systemic optimization of angles was recorded: an increase in φ in the starting phases of the pull (F1–F2) and in the final alignment (F10), which reflects a more compact landing and more stable verticalization of the torso (p<0,01–0,001), while a decrease in φ in the phases of the explosion and final acceleration (F3–F4), in the phases of the push and reception (F7–F9) and during “free fall” (F5) indicates more economical body control and more accurate stabilization under load (p<0,05– 0,001). This corresponds to higher technical skill and developed mechanisms of postural coordination. In athletes of group III (stage of specialized basic training), statistically significant (mainly p<0,05–0,01) improvements in angular parameters are observed relative to group I in most phases, which reflects the transition to an “economic” movement profile: a more compact body position in the zones of peak acceleration and barbell reception, smaller horizontal displacements and more stable trunk control. In athletes of group II (stage of preliminary basic training), selective positive changes (individual phases with p<0.05) were recorded – primarily in the phases of “preliminary acceleration” and reception and push, which indicates the formation of the foundations of “pelvis-knee-trunk” coordination and a gradual decrease in excessive angular deviations. In athletes of group I (stage of initial training), most of the indicators were biased or unreliable, however, initial biases were observed towards the alignment of angles in the reception and final straightening phases, which reflects the beginning of mastering the technical structure of the jerk. Originality. For the first time, 10-phase profiles of torso tilt angles in the jerk (80% 1RM) in weightlifters at 4 stages of long-term training are described and indicator phases for assessing/correcting technique are identified. Conclusion. The results obtained confirm the effectiveness of video analysis in Dartfish for phase monitoring of body angles and differentiated technique correction. In practice, it is advisable to select target exercises and control indicators (φ in F1–F4, F7–F10) taking into account the training stage, which allows to increase the stability of the reception, reduce excessive angular deviations and increase the reliability of fixation in the “classical jerk”.