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: 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.

Sports performance is influenced by a many of factors that can be characterised as its rela-tively independent – although synergetic – components. The most frequently mentioned are the fitness, somatic, tactical, mental and technical factors of sports performance. The subject of interest in sport is the process of monitoring and evaluating the level of these individual factors, i.e. the diagnostics of sports performance. When diagnosing the level of performance prerequi-site for tennis, it is recommended to use those diagnostic methods that focus on tennis-specific performance prerequisites. Analyses of modern tennis show speed (reaction, action), strength (explosive), strength endurance and specific coordination abilities to be the most important motor prerequisites. Diagnostics of the motor prerequisites of an athlete are often performed in practice employing motor tests and test batteries. Methods of evaluating the results obtained are generally based on the probability approach, though an alternative is provided by a method based on the theory of fuzzy logic. The aim of the research was to use the theory of fuzzy logic in evaluating the level of performance prerequisites and compare evaluation results by using of a classical discrete approach and a fuzzy approach. The two approaches are evaluated and compared using the results of testing of a group of 15–16-year old tennis players (n = 203, age M ± SD = 15.97 ± 0.57 years, height M ± SD = 181.9 ± 6.8 cm, weight M ± SD = 71.6 ± 8.6 kg) who took part in regular testing conducted by the Czech Tennis Association in the years 2000–2018 using the TENDIAG1 test battery. STATISTICA12 software was used for the anal-ysis of data using a probability approach. FuzzME software was used for analysis using of a fuzzy approach. The testing of research data (the Kolmogorov-Smirnov test) demonstrated the normal distribution of the frequency of the results of individual tests in the test battery. The level of agreement of the results (the Pearson correlation coeficient) obtained by the two approach-es (the discrete and the fuzzy approaches) was high both from the effect size (ES, large) and statistical significance points of view (r = 0.89, p = 0.05). The evaluation of the effect size (ES) of the differences between the mean values of the results obtained by the two approaches us-ing the Cohen’s d did not demonstrate any substantively significant difference (d = 0.16). For a more detailed analysis, two subsets were selected from the original group of tennis players. They consisted of players with an overall evaluation (probability approach) of 4–5 points and 8–9 points, respectively. The level of agreement between the results in the subgroup with the evaluation 4–5 points was low from both the effect size (ES, small) and statistical significance points of view (r = 0.15, p = 0.05), while the agreement in the subgroup with the evaluation of 8–9 points was at a medium level in terms of the effect size (ES, medium) and statistically insignificant (r = 0.47, p = 0.05). The effect size (ES) assessment of the differences between mean values of the results obtained by the two approaches did not demonstrate any effect (d = 0.12) in the group with the overall score of 4–5 points, and a large effect (d = 0.89, large) in the group with an overall score of 8–9 points. Despite the similarity of the results obtained by the probability and fuzzy methods, it was shown that the fuzzy approach enables a finer dif-ferentiation of the level of fitness prerequisites in players on the evaluation boundaries. Since that the results for individual items in the TENDIAG1 test battery indicate the level of individual performance prerequisites, the use of different weighting criteria may be considered for future evaluation using the fuzzy approach. For this approach, the use of the point method, a paired comparison method or the Saaty method can be considered for the identification and calcula-tion of individual subtests weighting.

The issue of the Relative Age Effect (RAE) has been monitored in the field of sports for more than 30 years. Its theoretical framework is based on the premise that during the pubescent period athletes born at the beginning of the year experience earlier biological acceleration re-sulting in a higher level of physiological, mental, morphological and psychological attributes than their later-born peers. A number of publications show that this temporary advantage often manifests itself in elite competitions at the junior level, but gradually disappears during the transition to professional senior competitions. The aim of this work was to determine the level of the RAE in the elite 100 ATP tennis players (ATP Rankings) in 2016–2018. To assess the influence of the RAE, the Chi-Squared (ꭕ2) test in the variant of Goodness of Fit was used for the assessment of the conformity of expected and observed frequency distribution due to the categorical character of the research data and the large sample size. The Cohen’s w val-ue calculation was used to assess the effect size (ES, since it is not a random representative selection of elements of the research set) of the ꭕ2 test values. The odds ratio (OR) was used to assess the chance of players from the Q individual quarters to get among the best 100 players. The results show that, in terms of effect size (ES), the effect of birth date in all the Top 100 players is small (w = .22) during the entire observed period 2016–2018; the influence of RAE is therefore dismissed. The ES in the individual years is again small (w = .21–.25); the influence of RAE is also dismissed. In analysing the effect of birth date, the mean rate of effect size was found in tennis players in positions 1 to 25 (w = .46) as well as in tennis play-ers in positions 51 to 75 (w = .37); the RAE influence is therefore not rejected. Only a small measure of effect size was found between positions 26 to 50 and 76 to 100 (w = .21–.25); the RAE influence is rejected. No statistically significant difference has been found between the observed and expected distribution of birth date between the observed quarters of the year (odds ratio test, p > .05) and it has not, therefore, been proven that tennis players from any of the quarters Q –Q had a better chance of getting among the Top 100 tennis players. It can be concluded that professional senior tennis had not shown the RAE influence to the extent usual in junior categories during the observed period of 2016–2018.

Aplikace fuzzy teorie v diagnostice výkonnostních předpokladů v tenisu Application of fuzzy theory in diagnosis of performance preconditions in tennis