A.N. Beleva¹
PhD N.B. Novikova^1
1Saint-Petersburg scientific-research institute for physical culture, St. Petersburg

Introduction. Repulsion is one of the key technical elements of ski jumping, largely determining the range and quality of flight. The level of technical preparedness of ski jumpers is most often assessed by the compliance of kinematic indicators with model requirements [1], but in order to assess the timeliness and accuracy of the application of efforts, it is necessary to determine the dynamic characteristics of repulsion [2].
The aim of the study is to identify the dynamic characteristics of repulsion in simulated exercises and real conditions of ski jumping.
Methodology and organization of the study. To compare the repulsion technique in ski jumping (K-40) in and simulation exercises of ski jumpers (N=7) aged 12-14, the dynamic characteristics of repulsion were recorded using an in-shoe pedograph F-scan. The mobile equipment of the in-shoe pedograph F-scan allows you to register the magnitude of timeliness and effort, the symmetry of the distribution of forces and the trajectory of the center of mass during repulsion on the separation table in a ski jump and in various conditions of performing simulation exercises.
The results of the study and their discussion. Significant differences in the technique of repulsion in ski jumping and simulation exercises have been identified. At the moment of reaching the peak of repulsion in simulation exercises, the reaction force of the support increases by about 2.5 times, and in ski jumping – by 1.25 times. The average duration of repulsion of young ski jumpers on a springboard is 0.23 ± 0.02 s, in exercises simulating repulsion from the acceleration rack - 0.42 ± 0.06 s, from the starting bench – 0.53± 0.10 s, in an exercise with repulsion on a rolling cart – 0.39 ± 0.05 s. A significant asymmetry of the effort of the right and left legs in pushing off on the springboard and in simulation exercises was revealed, which may be a consequence of an imbalance in the tone of the flexor and extensor muscles.
Young ski jumpers exhibit statistically significantly higher values of the total peak force in imitation of repulsion from the acceleration rack (104.58±23.04 kg), from the starting bench (90.32±18.37 kg) and on a rolling cart (96.27±24.62 kg), compared with ski jumping (70.98±39.90 kg).
Conclusion. The study of the dynamic characteristics of repulsion in ski jumping and simulation exercises showed the presence of motor asymmetry of the right and left feet, early transfer of body weight to the front of the feet, untimely manifestation of peak repulsion efforts. Significant differences in the reaction time and strength of the support during repulsion in all exercise variants have been determined. The data obtained indicate that the internal structure of the movements of young jumpers does not meet the modern requirements of ski jumping.

Keywords: ski jumping, simulation exercises, young ski jumpers, dynamic characteristics, technique.

References

1. Zebzeev V.V. Model of training young ski jumpers based on kinematic indicators of jumping technique / V.V. Zebzeev // Fizicheskaya kul'tura: vospitanie, obrazovanie, trenirovka.  2018.  No. 3.  pp. 38-39.
2. Virmavirta M. Ski jumping: aerodynamics and kinematics of takeoff and flight // Handbook of human movement. – URL: https://www.researchgate.net/publication/318466808_Ski_Jumping_Aerodynam... (accessed 06/15/2023).