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Asymmetry of lower limb strength and jumping ability of young soccer players

Rutkowska-Kucharska Alicja

Acta of Bioengineering and Biomechanics

2020

Vol. 22, no. 1

79--85

The aim of this study was to evaluate the potential correlation between asymmetry of lower limb muscle torque, asymmetry of vertical ground reaction force during take-off in young soccer players and their jumping abilities. Methods: Twenty-three young soccer player (16.9 ± 0.64 years old) participated in measurements. An isokinetic dynamometer, the Biodex System, was applied to test muscle torque (PT) of the knee flexors and extensors. The vertical ground reaction force (vGRF) was recorded from two Kistler plates. Jumping abilities were assessed with the horizontal (HJ) and vertical jump (VJ) tests. The asymmetry index (AI) was used to assess the asymmetry of the limbs. Results: The asymmetry index showed the highest asymmetry (over 10%) for the PT under static conditions for knee flexors and extensors. The correlation (–0.432, p = 0.038) was found between the asymmetry of vGRF and the height of the VJ. There was no correlation between the muscle torque and the height of the vertical jump. However, a correlation between the HJ length and muscle torque for flexors and extensors of the right and left lower limb was found. Conclusions: The asymmetry of the muscle torque of the flexors and extensors of the knee joint does not correlate with the results of both jumping ability tests. There was a statistically significant correlation between the vGRF asymmetry index during take-off and the height of the VJ. In the HJ, such a relationship was not found.

Stabilometric profile of handstand technique in male gymnasts

Sobera Małgorzata, Serafin Ryszard, Rutkowska-Kucharska Alicja

Acta of Bioengineering and Biomechanics

2019

Vol. 21, no. 1

63--71

This study aimed to determine the characteristic features of handstand posture control associated with a high level of ability among male gymnasts. Methods: 8 acrobatic gymnasts (4 more and 4 less experienced) participated in the study. They performed a 10-second handstand five times with each hand positioned on one AccuSway (AMTI) force platform and the other hand on the second. Body sway changes were recorded in time series: centre of pressure (COP) and components of the ground reaction force (GRF) (vertical, medial-lateral and anterior-posterior). The COP amplitude and average of GRF components, the index of frequency (by Fast Fourier Transform) for the right and left hand were calculated. Results: More experienced gymnasts performing a handstand concentrate mainly on minimizing anterior-posterior body sway with minimum medial-lateral body sway. Less experienced gymnasts’ pressure exerted on a surface by the hands is irregular in a medial-lateral direction. More experienced gymnasts control body position in the handstand and show less variation of body sway compared to less experienced gymnasts. More experienced gymnasts revealed lower frequency of body sway in the handstand compared to less experienced gymnasts. Conclusion: The stabilometric profile of more experienced gymnasts means the better posture control in handstand. The minimizing of body sway is compensated by exerting more force on a floor surface and the less experienced athletes cannot do that even after several years of training. The gymnasts of both groups, during standing on their hands, put more load on the right hand.