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  • Author: Jacek Stodółka x
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Structural asymmetry of foot arch formation in early school-age children

Summary

Study aim: the purpose of the study was to compare foot shapes in early school-age boys and girls.

Material and methods: the study included 90 boys and 98 girls aged seven to nine years old. The shape of the foot arch was examined using a podoscope. The longitudinal arch was assessed according to the Clarke angle value on the basis of Kasperczyk’s classification. The transverse arch was assessed according to the Wejsflog index. An analysis of variance, a post-hoc LSD test and a chi-square test were performed.

Results: normal transverse arches in both feet appeared in 84% of the examined children. An analysis of the average value of the Wejsflog index showed that it is similar and within limits in all of the test groups indiscriminately when it comes to gender and age. Normally, longitudinal arches in both feet occurr in 44% of children. The average value of Clarke’s index in a test group of school-age girls was within normal range while a functionally flattened foot appeared in the case of seven and eight-year-old boys.

Conclusions: the outcomes of the present study conducted on a randomly chosen group of developing boys and girls show that changes in foot structure are mostly symmetrical in nature (almost 90%), meaning that if the left foot is normal, the right one is normal, too. Gender had no effect on the foot build or arch type in either foot. The right and left feet showed symmetrical structure in the majority of the children.

Open access
Balance Maintenance in the Upright Body Position: Analysis of Autocorrelation

Abstract

The present research aimed to analyze values of the autocorrelation function measured for different time values of ground reaction forces during stable upright standing. It was hypothesized that if recording of force in time depended on the quality and way of regulating force by the central nervous system (as a regulator), then the application of autocorrelation for time series in the analysis of force changes in time function would allow to determine regulator properties and its functioning. The study was performed on 82 subjects (students, athletes, senior and junior soccer players and subjects who suffered from lower limb injuries). The research was conducted with the use of two Kistler force plates and was based on measurements of ground reaction forces taken during a 15 s period of standing upright while relaxed. The results of the autocorrelation function were statistically analyzed. The research revealed a significant correlation between a derivative extreme and velocity of reaching the extreme by the autocorrelation function, described as gradient strength. Low correlation values (all statistically significant) were observed between time of the autocorrelation curve passing through 0 axis and time of reaching the first peak by the said function. Parameters computed on the basis of the autocorrelation function are a reliable means to evaluate the process of flow of stimuli in the nervous system. Significant correlations observed between the parameters of the autocorrelation function indicate that individual parameters provide similar properties of the central nervous system.

Effects of Explosive Type Strength Training on Selected Physical and Technical Performance Characteristics in Middle Distance Running - a Case Report

Abstract

Introduction. Distance running performance is a simple function of developing high speeds and maintaining this speed as long as possible. Thus a correct running technique becomes an important component of performance. Technique is effective if the competitor can reach a better performance result with the same or lower energy consumption. The purpose of this investigation was to examine a six weeks application explosive type strength training on lower extremities power and maximum speed performance improvement in order to facilitate running technique in sub-elite male middle-distance runner. Material and methods. A sub-elite runner performed twice a week special exercises and running drills. He completed a pre and post-training jumping (SJ, CMJ, standing long jump, standing five jump) and speed (20 m from standing and flying start) field tests. For kinematical analysis, a video (SIMI Motion System) of a 10 m sprint from a 20 m flying start was collected. Results. Improvement occurred in all measurements but strong changes were evident in the 10 m from 20 flying start and in stride frequency from 3.90 to 4.01 Hz, due to decreasing of ground contact time from 160 to 156 ms. No strong evidence in the participant's running technique changes. Conclusion. This proved that six weeks of dynamic type strength program seems to improve neuromuscular characteristics of running speed and explosive power and no changes in running technique.

Open access