70 research outputs found

    The influence of Si/Al ratio on the distribution of OH groups in zeolites with MWW topology

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    A series of MWW-type zeolites of increasing Si/Al ratio were investigated with respect to their acidic properties. Concentration of the Brønsted acid centers located at the external crystal surface was invariant for the entire series. Ethanol conversion to ethyl-tert-butyl ether, proceeding only at the external surface, was also constant. The OH groups in MWW zeolites were found to be homogeneous with proton affinity value equal to 1142.7 kJ/mol

    Wheelchair Basketball Competition Heart Rate Profile According to Players’ Functional Classification, Tournament Level, Game Type, Game Quarter and Playing Time

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    Heart rate is a popular parameter observed in team sports to plan training sessions with regard to load and sport specificity. Wheelchair basketball is an intermittent team game for physically impaired players. The study aim was to define heart rate profile of wheelchair basketball players in terms of their functional classification (category A: 1.0–2.5 points, category B: 3.0–4.5 points), tournament level (championships and friendly games), game type (close, balanced, and unbalanced), game quarter (1st, 2nd, 3rd, and 4th) and playing time (40–59%, 60–79%, and 80–100% in a quarter). Heart rate of 18 wheelchair basketball players was monitored in 22 games in four different tournaments, i.e., European Championships 2017, World Championships 2018, two friendly international tournaments of national teams (2017 and 2018). Heart rate (HRmean, HRpeak, %HRpeak, HRR, and %HRR) was monitored by Polar Team Pro (Kempele, Finland) during playing time on the court. Timeouts, quarter breaks, a half break, time on a bench were not taken into account in HR monitoring. The Kolmogorov–Smirnov test, the Mann–Whitney U test and the Kruskal–Wallis test were used. Fourteen players divided according to the classification into category A and B were included in the final calculations (n = 457 cases). Significantly higher HRmean, %HRpeak, HRpeak, and %HRR were noted among category B players, and higher %HRpeak and %HRR among category A players at the highest tournament level compared to friendly games. There were significant differences in %HRR and the percentage of time spent in HR zone I between the players with different playing time (40–59% versus 60–79%) in category B. No significant differences in HR were noted between four quarters. Among category A players, differences in HR in zone II were observed. Among category B players, statistically significant differences in % HRpeak, the percentage of time spent in HR zones I, II, III, and %HRR between close, balanced and unbalanced games were found. In conclusion, the intermittent nature of wheelchair basketball was confirmed. Monitoring heart rate in a game could be helpful in creating exercises with proper loads for better physical preparation of wheelchair basketball players. High intensity training sessions would be more beneficial in preparing players for game demands

    Laboratory and Non-laboratory Assessment of Anaerobic Performance of Elite Male Wheelchair Basketball Athletes

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    Wheelchair basketball is an adaptive Paralympic sport and wheelchair basketball players are under classification in sport. Coaches are looking for useful assessment tools (field-based tests) to evaluate players’ anaerobic performance (anaerobic capacity). The aim of this study was to assess the validity of field-based tests for anaerobic performance evaluation for two functional categories of wheelchair basketball players and to create a calculator to predict mean or peak power on the basis of the selected field-based test results. Sixty-one elite male wheelchair basketball players performed the Wingate Anaerobic Test and the following field-based tests: 3 m sprint, 5 m sprint, 10 m sprint, 20 m sprint, basketball chest pass test, medicine ball (3 kg) chest pass test, bilateral handgrip, 3-6-9 m drill test, 30-s sprint test, agility drill test and 10 × 5 m sprint test. The participants were divided into two functional categories: A (classes from 1.0 to 2.5; n = 29) and B (classes from 3.0 to 4.5; n = 32) according to the International Wheelchair Basketball Federation rules. The large effect size (Cohen’s d > 0.5) was found in four tests (3 m sprint, 5 m sprint, basketball chest pass test, medicine ball chest pass test; ES 0.90, 0.53, –0.96, –1.05). There were differences between category A and category B players regarding mean power, peak power and relative peak power. Peak power correlated with four tests, while mean power correlated with eight out of eleven tests. The formulas for estimating peak power or mean power in category A and B players were created separately. All the analyses confirmed that 3 m sprint, 5 m sprint, 10 m sprint, 20 m sprint, agility drill test, bilateral handgrip, 3-6-9 m drill test, 30-s sprint test, basketball chest pass test and medicine ball chest pass test are valid for non-laboratory anaerobic performance evaluation. Using the four formulas as a tool to predict mean or peak power on the basis of the selected field-based test results and functional categories will be helpful and will allow coaches and players to prepare pre-season, post-season and in-season conditioning exercises in wheelchair basketball

    The international wheelchair basketball federation’s classification system: the participants’ perspective

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    The purpose of this exploratory study was to evaluate opinions of elite athletes, coaches and classifiers regarding the International Wheelchair Basketball Federation’s (IWBF) functional classification system. We were also interested in the athletes’ perspective regarding potential changes to the classification system. In addition, we compared the generalized opinions reported by the athletes to those of coaches and classification officers. This survey was administered during the Wheelchair Basketball Gold Cup (Amsterdam, 2006). Seventy-nine athletes, 50 men and 29 women, as well as 12 coaches and 14 classifiers completed the survey. The first part of the survey addressed demographic characteristics of the participants. The second part focused on their opinions regarding the current classification system. Based on the survey responses, athletes reported that the IWBF classification system is generally satisfactory. However, athletes as well as coaches and classification officers did report some specific concerns about this classification system. These concerns included changes in an athlete classification, athlete cheating and communication between classifiers and athletes. Athletes, coaches and classifiers, as the wheelchair basketball’s primary constituent groups, have a vested interest in the evolution of the game and should be included in the evaluation and modifications to the functional classification system. This study has demonstrated that a classification specific survey could provide useful information and insight into the perspectives of these constituent groups

    Reliability of measurement of active trunk movement in wheelchair basketball players.

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    The study aim was to assess the reliability to active trunk movements measurement in four sitting positions in wheelchair basketball players and to check their trunk movements in these positions. Eighteen volunteer wheelchair basketball athletes, with a minimum of five years' training experience, were asked to perform the maximum range of active trunk movement in three planes in four sitting positions (in a sports wheelchair with straps, without straps, on a table with feet on the floor, on a table without foot support). The range of movement was measured by the Kinect for Windows V2 sensor twice (with one-week interval). To assess the reliability, different statistical methods were used for each movement: significance of differences between the results (p-value), interclass correlation coefficient (ICC) and minimal detectable change (MDC). The limits of agreement analysis (LOA) were calculated. Differences between trunk movements in four positions were checked by the MANOVA (Wilk's Lambda and ETA2 were calculated if data were normally distributed). The significance level was set at α .05, no differences between the results, "very good"ICC, between .96-.99). In the position with straps, the trunk movement was significantly bigger than in other positions (p .05). The Kinect for Windows V2 sensor measured active trunk movement in a reliable manner and it can be recommended as a reliable tool for measuring trunk function. Utilizing straps by wheelchair basketball players increases their trunk movement
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