Lukášek, M., & Kalichová, M. (2015). Injury risks of heading in young football players. J. Hum. Sport Exerc., 9(Proc1), pp.S490-S499. The aim of the research is to contribute to findings concerning increasingly acute problems connected with heading in football. Unlike most of available studies where heading with adults is dealt with, our study focuses primarily on heading with children. 16 children aged 10, weighing 36.2 ± 4.7 kg took part in the research. Each tested person executed headings of a ball dropped from 0 m (3.13 m/s), 1 m (4.43 m/s) and 1,5 m (5.43 m/s) ie. 3 headings in total. The total number of tests was 48. A triaxial accelerometer (1000 Hz) was used in the measurements. As presumed, with increasing drop-height the head acceleration increased on impact. With drop-height of 0.5 m we recorded 59.4±15.8 m·s-2, with 1 m we measured 76.4±15 m·s-2 and 100.1±25 m·s-2 from 1.5 m. These acceleration values do not pose danger if individual, however, we came to conclusion that repeated impacts, especially those of higher speed, may lead to functional problems of a child's brain.

Purpose: Change of direction speed (CODS) and reactive agility (RAG) are important qual-ities in futsal, but studies rarely examined the predictors of these conditioning capacities in players of advanced level. This study aimed to evaluate predictive validity of certain an-thropometric and conditioning capacities in evaluation of futsal specific CODS and RAG in top-level players. Methods: The sample comprised 54 male players from Croatia and Bosnia and Herzegovina, members of teams competing at the highest national rank, including national champions for the 2017–2018 competitive season in both countries. The variables comprised set of pre-dictors (body mass, body height, triceps skinfold, reactive strength index [RSI], sprint 10 m [S10M], and broad jump [BJ]; and four criteria: futsal specific CODS and RAG, performed with and without dribbling (CODS_D, CODS_WD, RAG_D, RAG_WD). To identify the asso-ciation between variables Pearson’s correlation and multiple regressions were calculated. Results: Observed predictors explained statistically significant (p < 0.05) percentage of vari-ance for all four criteria (Rsq: 0.28, 0.30, 0.23 and 0.25, for CODS_WD, CODS_D, RAG_WD, RAG_D, respectively). Body mass was significant predictor for all criteria (Beta: 0.35–0.51), with poorer performances in heavier players. In both performances which involved dribbling, significant predictors was RSI (Beta: −0.27 and −0.31 for CODS_D and RAG_D, respective-ly), with superior performances in players with better RSI. The S10M and BJ were not identi-fied as being significantly correlated to studied RAG and CODS performances. Conclusion: Study confirmed specific influence of studied predictors of futsal specific CODS and RAG with consistent negative influence of body mass on studied performances. Almost certainly this can be explained by specifics of RAG and CODS execution. Specifically, tests are performed over relatively small distances, with several changes of direction, which clear-ly mimic the futsal specific performances. Although sprint performance is often observed as important determinant of CODS and RAG, herein we did not confirm its predictive validity in explanation of futsal specific CODS and RAG. Future studies should evaluate other poten-tially important predictors of these capacities in futsal.

Purpose: Classical ballet, Slovakian folklore dance, and sport dance training differ in their way how to master the art of dance; however, postural control is essential for the correct exe-cution of complex movements used in all types of dance. The aim of this study was to analyse the differences in static postural control between classical ballet dancers, Slovakian folklore dancers and sport dancers and to analyse the effect of body mass, body height and toe grip strength on postural control. Methods: 68 dancers, between 17 to 28 years of age, participated in this study: 21 dancers from Slovakian folklore dance group VSLPT Poľana Brno (12 females, 9 males), 22 dancers from Brno Dance conservatory (16 females, 6 males) and 25 sport dancers competing at Brno Dance Open 2019 (12 females, 13 males). All participants were asked to stand upright, barefooted, arms along the body, both feet on the Emed-at platform (Novel GmbH, Germany) for 10 seconds with their eyes open to obtain the length of COP line (cm), average velocity of COP (cm/s), the elliptic area (mm2) and numerical eccentricity of the ellipse. The toe grip strength was measured for each foot when sitting using toe grip dynamometer (Takei Scien-tific Instruments, Niigata, Japan). To analyse the effect of dance style, to grip strength, body mass, body height, and gender on postural control variables, Kruskal Wallis test, and Spear-man Rank Order Correlation were used. Results: Abetter postural stability measured by the length and average velocity of COP was observed in sport dancers, compared to classical ballet and Slovakian folklore dancers. Sport dancers are used to a greater load on the forefoot and to a special foot roll-of pattern when dancing, which may lead together with a constantly changing environment during competi-tions to their enhanced postural stability. Despite the differences in dance training and dance footwear of female and male dancers (high-heel shoes in sport and Slovakian folklore female dancers, pointe shoes in female ballet dancers), no statistically significant difference in pos-tural variables between genders was observed. Similarly, in analysed dancers, no effect of age, body mass, and body weight on postural control were observed. The toe grip strength was not observed to affect the postural variables in this study. The greatest toe grip strength was observed in female ballet dancers, despite their younger age. Ballet dance training in-cludes repetitive exercises focused on foot and toes such as battement tendu or demi-pointe and en pointe positions probably resulting in the greater strength of the toes. Conclusion: In this study, better postural stability measured by the length and average ve-locity of COP was observed in sport dancers, compared to classical ballet and Slovakian folklore dancers. In analysed dancers, no effect of body mass, body weight, gender, and toe grip strength on postural control variables was observed. Future studies focused on postural stability changes in non-dancers after a sport dance, classical ballet and Slovakian folklore dance training program would provide additional knowledge about the process how each type of dance enhance the balance and other coordinative skills.

Purpose: The purpose of this study was to analyse differences in postural stability between athletes with ID competing in Alpine and Cross country (XC) skiing to assess the effect of special sports training on postural stability in persons with ID. Methods: Athletes with ID were divided into four groups by their discipline: Alpine skiers (n = 9), XC skiers 2.5 to 10 km (n = 10), XC skiers 500 to 1000 m (n = 18) and XC skiers 50 and 100 m (n = 10). All participants were asked to stand barefooted on the Zebris FDM platform (Medical GmbH, Germany) with their eyes open and closed. To compare differences between groups one-way ANOVA with Tukey HSD test was used. To compare the difference between the eyes open and closed, t-test was used. Results: Statistical analysis showed no significant differences between Alpine and XC skiers in analysed variables. The analysis of COP velocity showed superior postural stability in XC skiers 2.5 to 10 km compared to XC skiers 500 and 1000 m. In XC skiers 500 and 1000 m, XC skiers 2.5 to 10 km and Alpine skiers a significant increase in COP velocity was observed when having the eyes closed. In XC skiers 50 and 100 m, no statistically significant differences between the eyes open and closed conditions were observed. Conclusions: Despite different sports training, no difference between Alpine and XC skiers in postural stability was observed. When comparing XC skiers, better postural stability was observed in skiers running longer distances, suggesting that this sports training enhances balance skills needed in everyday life.

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