Left-handed Players Research Articles

Performance of Elite Women's Singles Badminton Players: The Influence of Left-Handed Players.

The purpose of the study was to analyze the influence of left-handed athletes on the opponent (right-handed players) of elite badminton women's singles. The study selected a total of 40 women's singles matches played by elite female players: twenty matches (42 games, n = 42) were played between left-handed and right-handed players and twenty matches (44 games, n = 44) were played between two right-handed players. There were significant (p < 0.05) differences in hitting positions, techniques, routes and landing points. No significant (p > 0.05) differences were found in scores per game and frequency distribution of rally outcomes. In conclusion, the details of technical and tactical application were different in two game forms, the main impact of the left-handed player on the opponent's (right-handed player) game was a decrease in the opponent's stroke in the overhead, an increase in the number of drives, predominance of small slashes and a decrease in big slashes.

Identity Formation of Left-Handed Athletes: Focusing on the Process and Change

This study analyzed the social process of identity formation in left-handed athletes. It used convenience and snowball sampling methods for in-depth interviews and recruited participants through a network of left-handed athletes who nurtured an interest in academic research and expressed willingness to participate. The results of this study are as follows. First, left-handed athletes experienced social discrimination and disadvantage due to prejudice against left-handed people before starting sports. Through the social discrimination and disadvantage, they unknowingly developed a negative view of left-handers and experienced a socially isolated phenomenon. Second, left-handed players discovered a new self as they start exercising. They experienced the advantage of being a left-handed player in a sporting event and were recognized as useful players on the team. Third, left-handed athletes who demonstrate excellent skills in athletics received a lot of attention from peers and parents even after they enter society, served as role models, and were recognized for their abilities. Through this process, left-handed athletes can lead a dignified life as members of society with confidence as left-handed athletes. This study is significant in that it analyzes the socialization process of identity formation experienced by left-handed athletes as they start exercising.

Kinematic differences between left- and right-handed cricket fast bowlers during the bowling action.

Despite differences between left- and right-handed athletes in other sports, minimal evidence exists regarding biomechanical similarities and differences between left- and right-handed cricket fast bowlers performing an equivalent task. This study aimed to compare the kinematics between left and right-handed fast bowlers performing an equivalent task (i.e. bowling 'over the wicket' to a batter of the same handedness as the bowler). Full body, three-dimensional kinematic data for six left-handed and 20 right-handed adolescent, male, fast bowlers were collected using the Xsens inertial measurement system. Time-normalised joint and segment angle time histories from back foot contact to follow-through ground contacts were compared between groups via statistical parametric mapping. Whole movement and subphase durations were also compared. Left-handed players displayed significantly more trunk flexion from 49%-56% of the total movement (ball release occurred at 54%; p = 0.037) and had shorter back foot contact durations on average (0.153 vs 0.177 s; p = 0.036) compared to right-handed players. Left- and right-handed bowlers displayed similar sagittal plane kinematics but appeared to use non-sagittal plane movements differently around the time of ball release. The kinematic differences identified in this study can inform future research investigating the effect of hand dominance on bowling performance and injury risk.

Influence of functional asymmetry on performance of technical actions at freestyle wrestlers

Purpose: to reveal the influence of functional asymmetry on the performance of technical actions in freestyle wrestlers. Material and methods. Analysis of scientific and methodical literature and Internet sources; pedagogical testing; pedagogical experiment; methods of mathematical statistics. The profile of functional asymmetry of the brain in freestyle wrestlers was determined. We used the tapping test by E. Ilyin, tests to determine motor and visual asymmetry and dynamometry. According to the results of the tapping test, E. Ilyin, the coefficient of functional asymmetry was calculated based on the working capacity of the left and right hands. 24 freestyle wrestlers aged 18-21 took part in the study. Results: during the previous study it was found that wrestlers mainly perform technical actions in one direction. A sportsman at the initial stage of training must learn techniques in both directions. However, at the stage of maximum realization of individual capabilities this rule should not always be observed. Since the majority of respondents suggested that in order to improve sports results it is necessary to strengthen the asymmetry of the wrestler, a set of special exercises was applied in the experimental group. In the given complex the accentuated performance of basic technical actions in a convenient way, individual dosage of exercises on development of flexibility, force, and also static endurance on the leading side was provided. After conducting the pedagogical experiment, we again conducted educational and training matches and analyzed them according to the indicators that were interesting to us. Having processed the results obtained after conducting the pedagogical experiment, we reached the following conclusions. In the control group, the increase in results for all indicators was: «right-handed people to the right» - 4,4 %; «right-handed to the left» - 0,8 %; «left-handed to the right» - 3,9 %; «left-handed to the left» - 10,9 %. In the experimental group, according to the same indicators, we observed the following increase in results: «right-handed to the right» - 13,5 %; «right-handed to the left» - 0,4 %; «left-handed to the right» - 0,5 %; «left-handed to the left» - 18,7 %. The conducted statistical processing made it possible to establish that there was a reliable increase in technical actions in the convenient direction for both right-handed and left-handed players. Summarizing the results of the pedagogical experiment, we can come to the conclusion that the use of a set of exercises embedded in the accented execution of technical processes in the leading direction contributes to the increase in results and the increase in the efficiency of the execution of technical processes. Conclusions. The analysis of the distribution of the individual profile of functional asymmetry in freestyle wrestlers showed that among the 24 wrestlers we studied aged 18-21 years, the right-sided profile of functional asymmetry predominates – 66 % of wrestlers, the left-sided profile of functional asymmetry has 20 % of wrestlers, the rest 14 % are ambidexters. The presence of a connection between the performance of a technical action and the profile of functional asymmetry in wrestlers was revealed: athletes perform technical actions in the leading direction more often and more efficiently. The use of a complex of exercises aimed at increasing asymmetry contributes to the growth of technical processes, and more pronounced in the leading direction. Thus, the increase in the control group «right-handed to the right» was 4,4 %, «left-handed to the left» - 10,9 %, in the experimental group – 13,5 % and 18,7 %, respectively.

Heatmap Analysis to Differentiate Diverse Player Types in Table Tennis—A Training and Tactical Strategy Development Potential

(1) Background: Computer-based analyses have been widely used to study aspects of various team and racket sports. However, such analyses have so far eluded table tennis, except in special competition forms, under fixed laboratory conditions or have only tracked the ball. The aim was to detect a basic, global, positional behavior, independent of the score. (2) Methods: We investigated the player position of professional male table tennis players with respect to handedness (right/left), playing system (offensive/defensive) and racket holding (shakehand/penholder) to determine the applicability of automated analysis systems. We used existing video data of competitive matches (N = 198 sets; 2006–2020) and transliterated them into an x–y coordinate system. From this, we were able to conduct a heatmap analysis for different types of players. (3) Results: The comparison between right- and left-handed players resulted in a significant difference in the positioning of the x coordinate (D = 0.5663; p = 0.001). Both groups positioned themselves on average in their own backhanded half of the table (Re: x = −0.22 m, Li: x = 0.39 m). (4) Conclusions: Our results have yielded valuable insights into the importance of analyzing positional behavior in a differentiated manner depending on handedness, playing strategy and racket holding posture.

Teaching Ergonomic Training Skills to Reduce the Fall Risk in an Elderly Patient - A Case Study

Background: Ergonomics is a study in the efficiency of movement. This can be an important tool when examining a patient to determine what a root cause of a patient’s dysfunction is. And then, what can be done to resolve that dysfunction. Accepting a patient’s medical diagnosis, age, or self-report as to what their problem is, may not be the best measure of a patient’s loss of function. This is especially true when the clinician may be biased against a patient due to their advanced age. Case Description: The following is a case report of a 68-year-old man named ‘Casey’ (not his real name), who was diagnosed with vertigo and with shoulder pain due to arthritis. Casey had fallen several times in the recent past and his physician had advised him to stop playing sports to protect him from injury. The shoulder evaluation was revealing for loss of motion and weakness. However, Casey’s balance and coordination skills were primarily intact. There did not seem an obvious cause for a history of falling. On taking Casey out to the parking lot, he could easily field, catch, and throw a ball without difficulty. It was noted that Casey was left handed and further noted that he had recently started playing third base. As a left handed player, Casey needed to pivot almost 180 degrees every time he threw the ball to first base. This was a difficult movement pattern for Casey, and he lost his balance every time he had to field a ball, pivot 180 degrees and throw the ball to ‘first base’. It was likely that Casey did not have as much of a problem with vertigo as he did with learning an efficient movement pattern that would allow him to play third base as a left handed player. Casey was seen 5 times in physical therapy and was taught lower extremity movement patterns so he could safely throw a ball to first base without losing his balance. Casey accomplished this very quickly, which then let us focus on his limitations in shoulder pain and weakness, which also recovered quickly. Discussion: A Medical Diagnosis will usually offer an incomplete description of the patient. The Physical Therapist needs to be mindful in studying the patient’s movement, which will be helpful in revealing a root cause of a patient’s loss of function. This is especially true in the elderly, who we expect to have limited abilities.

Analysis Of The Water Polo Shots In Positions 1 And 2 In The Simple Temporal Numeric Inequality With Possession During The 15th Fina World Championship In Barcelona 2013

INTRODUCTION: The Simple Temporal Numeric Inequality With Possesion (FJs) is defined as a concrete micro-situation of the Water Polo, which alter the amount of players (+1) in favor of the team that owns the ball. Left-handed (LH) players may have an important role. AIM: First, to know if the LH players were more effective in the goal categories and getting positive actions in position 1 and 2 than the right-handed (RH) in the FJs; second, to know if the shots in position 1 and 2 were less effective than the rest of the positions in the goal categories. METHODS: An observational, multidimensional, nomothetic and punctual study was developed, following Anguera (2003). The sample consisted on all the throws during 24 games, including male and female teams (n=127) corresponding to the 15th FINA World Championship using an ad hoc instrument for observation through SportCode software. Games were recorded with a video camera (SONY, FDRAXP33B.CEN). Descriptive of all variables and Chi-square test were obtained to compare throws. RESULTS: The LH players performed from position 1 more total shots compared to the RH players. Adding the categories related to the goal, the LH got 30.8% and the RH 23.1%. When adding the categories related to positive actions (exclusion, penalty, rebound and corner), the LH got 42.3% while the RH 25%. From position 2 the RH players make more shots compared to LH players (50 vs 25). Adding the categories related to the goal, the LH got 10.7% and the RH 26.7%. If we add the categories related to positive actions, the LH got 16% while the RH 38.7%. The Specific Position (PE) and Player’s Laterality (LJ) of the shots from position 1 and 2 that finish in goal in FJs, there were significant differences (p < .05). CONCLUSIONS: The LH players were more effective in the goal categories and getting positive actions in position 1 than the RH, but not in position 2. Only the shots in position 1 were less effective than the rest of the positions in the goal categories.

Analysis of the shots in positions 1 and 2 in even situational framework during the World Championship of Barcelona 2013

The purpose of this study was, on one hand, to know if the left handed players were more effective in the goal categories and getting positive actions in 1 and 2 position than the right handed in the same offense position in Even Situational Framework (FJa). On the other hand, to know if the shots in 1 and 2 position were less effective than the rest of the positions in the goal categories. The methodology was observational, multidimensional, nomothetic and punctual. The sample was all the throws of 24 games (12 male and 12 female) in the 2013 World Championship in Barcelona using an ad hoc instrument for observation through the SportCode software, which was also used to record the data. Descriptives and Chi-square test were obtained and the conclusions are that the left-handed players are more effective if we relate them to the goal categories and positive actions from positions 1 and 2. However, the righties are more effective if we only see the categories related with the goal.

Diferencias en las estadísticas de competición de tenis en los juegos olímpicos de Río de Janeiro 2016

El objetivo de este estudio fue conocer las estadísticas de competición de tenis en los JJOO de Río de Janeiro 2016. Para ello, se analizaron 282 sets de los 128 partidos en los que participaron un total de 128 tenistas (64 jugadores y 64 jugadoras). Los datos fueron seleccionados de la información publicada en la Web Oficial de la Federación Internacional de Tenis (http://www.itftennis.com/olimpiadas/cuadros). Los resultados mostraron que el género masculino obtuvo valores estadísticamente superiores en variables relacionadas con el servicio, mientras género femenino obtuvo mejores valores en variables relacionadas con el resto. Con respecto a la lateralidad, no se encontraron diferencias significativas entre zurdos y diestros en el género masculino. En el género femenino, las jugadoras zurdas obtuvieron unos valores significativamente superiores en el porcentaje de puntos ganados con el primer y segundo saque, número de puntos de break y número de puntos ganados al resto. La información obtenida en este trabajo establece unos parámetros de rendimiento que pueden resultar de utilidad para establecer objetivos y evaluar el rendimiento de los jugadores de tenis.

Do left-handed players have a strategic advantage in table tennis?

The reasons for the overrepresentation of left-handed players (LHps) in some sports are widely discussed in the literature. In light of this debate, this study aimed to assess the associations between players’ handedness and selected performance indicators in table tennis, where LHps represent 25% of top-level players. A notational analysis was conducted on 20 men’s matches including any combination of players’ handedness. Participants were in the first 150 positions of the ITTF world ranking at the moment the matches were played. The table area of ball bouncing after serving, and the shot type used by the receiving and subsequently the serving player, were recorded for 1515 rallies. Each half of the table was divided into six equal rectangular areas. There was a significant effect of players’ handedness on percentage of ball bouncing in different areas. Specifically, LHps showed a greater capacity (or choice) to adjust the serve (in terms of areas of ball bouncing) than right-handed players (RHps) according to the opponent’s handedness. Furthermore, LHps used offensive shots more frequently. In conclusion, both play strategy and characteristics such as higher offensiveness, together may contribute to the success of LHps in table tennis. These findings emphasise the need for a multifactorial approach in future research aiming to understand why LHps may be advantaged in different sports.

Lateral differences in maximal grip strength in Czech male tennis players aged 11 – 12 in the context of injury prevention

The term laterality indicates the one-sided preference or functional advantage of the stronger, more accurate and coordinated limbs or organs and the brain hemisphere of a human body. In the preference process, more accurate, precise, coordinated and stronger side is chosen from the perspective of motoric functions. Among the general population is about 10-13% of left-handers and in certain sport fields this percentage may (baseball, tennis, box etc.). The left-handed dominance in tennis is considered an advantage. Due to unilateral load, there may be an excessive side-effect in strength differences in tennis and overloading of specific muscle group could lead to an injury. The aim of the research was to identify the levels of somatic and strength characteristics and assess the lateral difference in maximal grip strength of Czech elite male tennis players. The sample consisted of male tennis players, ranging in age from 11 to 12.9 years (n=186) who participated in the regular tests for Czech Tennis Association in years 2000-2018. Base anthropometrics were measured (height, weight) and maximal grip strength of both hands using the hand-held dynamometry (Grip D, Takei). Data came from normal distribution (statistically proven – chi-square test). The basic statistical characteristics were calculated (body height, M=155.08±7.98 cm; body weight, M=43.45±7.13 kg; strength of right hand: M=24.88±4.67 kp; strength of left hand: M=21.70±4.74 kp). It was found that 87.6% of the players (n=163) were right-handed and the remaining 12.4% left-handed (n=23). The assessment of the significance (Cohen´s d) between the dominant (playing) hand for the right-handed and left-handed players showed small effect size (dominant hand right: MRHR=25.11±4.41 kp, dominant hand left: MLHL=26.62±5.65 kp; d=0.30, small) in favor of the left-handed players. The difference between the dominant and the non-dominant hand showed large effect size for the right-handed (dominant hand right vs. hand left; MRHR=25.11±4.41 kp, MRHL=21.01±4.15 kp, d=0.96, large) and medium effect size for the left-handed players (dominant hand left vs. hand right; MLHL=26.62±5.65 kp, MLHR=23.24±5.98 kp, d=0.58, medium). The results showed that the value of 15 % level of strength laterality between dominant and non-dominant hand was exceeded for the right-handed (55.83 %) and left-handed (43.48%) groups ergo the exceeded value could be a cause of injuries. Because of this signals attention should be given during training process for optimizing the required load.

Kinect-Based Badminton Motion Analysis Using Intelligent Adaptive Range of Movement Index

Badminton is a type of racquet sport that is played using racquets to strike a shuttlecock within a netted rectangular court, and it is one of the most popular sport in Malaysia. In this paper, the team expanded their previous adaptive novel lossless compact view invariant compression technique, named adaptive range of movement index (RoMI) by embedding an intelligent mapping algorithm. Badminton players are broadly classified into two handedness groups, which are left-handed players and right-handed players. The adaptive RoMI technique in the previous module is capable of identifying the labels of normalized RoMI and perform adaptive mapping for badminton players of different handedness. However, the mechanism requires manual judgement from humans to select the type of handedness. This technique will increase the error rate and effort of importing data properties with incorrect manual handedness input or data stream from different handedness datasets of badminton players. Thus, the proposed intelligent adaptive RoMI technique enables the analyzing system to outperform the previous module by detecting the labels of normalized RoMI automatically and by performing intelligent mapping. The motion analysis system will then become much more efficient, intelligent hence simplifying data collection and the handedness invariant benchmarking approach.

Clustering tennis players’ anthropometric and individual features helps to reveal performance fingerprints

The study was aimed to explore distinct players’ groups according to their anthropometric and individual features, and to identify the key performance indicators that discriminate player groups. Match statistics, anthropometric and personal features of 1188 male players competing during 2015–2017 main draw Grand Slam singles events were collected. Height, weight, experience, handedness and backhand style were used to automatically classify players into different clusters through unsupervised learning model. Afterwards, 29 match variables were analysed through MANOVA and discriminant analysis in order to evaluate the different match performance among player groups and to identify the key performance indicators that best differentiate player clusters in each Grand Slam. The analysis revealed the existence of four clusters, they were classified as Big-sized Right Two-handed Players (n = 387), Medium-sized Right One-handed Players (n = 265), Small-sized Right Two-handed Players (n = 414), and Left Two-handed Players (n = 122). Serve, winner, net and physical performance-related indicators (Structure Coefficient ≥ |0.30|) were showed to be the maximum contributors to the group separation. Left-handed players were the most homogenous group in performance. Taller players outperformed their peers in all Slams except for Roland Garros, where left-handed players demonstrated certain advantage playing on slow-pace surface. In Wimbledon and US Open, Medium-sized Right One-handed Players showed better net and physical performance. The advantage of left-handed player is over-represented at elite level. Current findings promote a better understanding of match-play from distinct player groups and offer information on evaluating contextual variability for achieving better performances.

Shoulder and elbow pain in junior high school baseball players: Results of a nationwide survey

BackgroundDespite proposals and guidelines to prevent baseball injuries in young players by societies and organizations, many shoulder and elbow injuries continue to occur among junior high school baseball players. In order to investigate the training conditions of junior high school baseball players and the risk factors for shoulder and elbow pain in the players, we conducted a questionnaire survey among junior high school baseball players throughout the country. MethodsThe questionnaire survey was conducted among junior high school baseball players in September 2016. ResultsA total of 11,134 junior high school baseball players belonging to 495 teams responded to the survey. Among these, 4004 players trained every day of the week and 1151 players played baseball games every month with no off-season. Among 9752 players who did not have shoulder and/or elbow pain in the spring and summer of 2015, 19.2% of players experienced elbow pain over the course of one year, 13.6% of players experienced shoulder pain, and 28.0% complained of shoulder and/or elbow pain. The frequency of elbow pain was more than that of shoulder pain. At risk for shoulder pain were pitchers and catchers and second-year students, while risk factors for elbow pain were playing pitcher and catcher positions, pitching or throwing ≥300 balls per week, playing ≥10 games on average per month and being left-handed. ConclusionRisk factors for shoulder pain were different from those for elbow pain. To prevent elbow pain, coaches should pay attention to pitchers and catchers and left-handed players and not allow players to pitch or throw ≥300 full-power balls per week or participate in ≥10 games per month. They should also pay attention to pitchers and catchers and second-year students to prevent shoulder pain. It is important for coaches to train multiple pitchers and catchers.

Combined Training of Plyometric-Speed for Enhancing Home First-Base Race of Baseball Players, Junior Category

In the last seasons the junior baseball teams of Matanzas have shown poor effectiveness in the run of the bases, having speed a determining factor in the game and therefore essential to achieve success in a baseball game. The objective of this research is to design a combined plyometric-speed training to enhance the run to first base home in baseball junior category players. To do this, a training program is applied based on the combination of plyometric and speed exercises dosed in three stages: first, general strength and low intense plyometric exercises, then, the introduction of moderate intensity plyometrics, and finally, the combined work of plyometrics of moderate-high and high intensity with speed exercises. The sample studied was composed of ten junior players, who participated in the XLVI Cuban Baseball National Championship. Three measurements were taken: first, at the end of the anatomical adaptation phase, then at the end of the muscular hypertrophy phase and the beginning of the intramuscular coordination-maximal strength combined with explosive strength and finally in the special preparation stage. To analyze the effectiveness of the exercises proposed in the time of the first home base race and in the reaction time, analysis of variance is applied, with a level of significance equal to 0.05. It is shown that there are significant differences in the time taken in the test that included the home first base racing, between each of the moments of preparation that were made, with a decrease of 4.40%. Meanwhile, in the first base home test hitting the hand with which the player batted and the moments in which controls were made influenced in the home first base time, showing a decrease of 3.38% in the effectiveness of the first base home race between the controls and a 3, 31% in the left-handed players in relation to the right-handers. On the other hand, in the test with a medical ball of 3kg with rotational movement and home-first base race, a decrease in the time of effectiveness of 6.33% is reflected In the study, it is confirmed that there is a decrease in times with medical ball throwing (3kg) with rotational movement and home first base with a decrease in the effectiveness of 3.19% between the initial and final control.

The advantage of lefties in one-on-one sports

AbstractLeft-handers comprise approximately 15% of professional tennis players, but only 11% of the general population. In boxing, baseball, fencing, table-tennis and specialist batting positions in cricket the contrast is even starker, with 30% or more of top players often being left-handed. In this paper we propose a model for identifying the advantage of being left-handed in one-on-one interactive sports (as well as the inherent skill of each player). We construct a Bayesian latent ability model in the spirit of the classic Glicko model but with the additional complication of having a latent factor, i.e. the advantage of left-handedness, that we need to estimate. Inference is further complicated by the truncated nature of data-sets that arise from only having data of the top players. We show how to infer the advantage of left-handedness when only the proportion of top left-handed players is available. We use this result to develop a simple dynamic model for inferring how the advantage of left-handedness varies through time. We also extend the model to cases where we have ranking or match-play data. We test these models on 2014 match-play data from top male professional tennis players, and the dynamic model on data from 1985 to 2016.

Relative age effect and left-handedness in world class water polo male and female players

ABSTRACTMost studies of the relative age effect (RAE) refer to popular sports. In contrast, we examined to what extent the RAE is present in elite water polo players, as well as the association between handedness and RAE. For these purposes, laterality, anthropometry, month of birth, performance and playing position of participants in the 2011, 2013 and 2015 World Championships (623 women, 622 men) were analised. No RAE was observed in the total sample. However, the proportion of male left-handed field players born in the first quarter (11%) was lower than those born in the second (35.3%) and fourth quarter (29.4%). Regarding the overall laterality, the amount of left handed players was similar to the general population (10%). Nevertheless, there was a larger amount of left-handed wings than expected both in men (23.7%) and women (34.4%). Left-handed male players performed more shots, shots/minute and also scored more goals than right-handed players. Women left-handed players were younger and they performed more shots/minute. There is no RAE in elite male and female water polo players. However, laterality could be a possible moderator of the RAE particularly in left handed players, which should be taken into account in future studies.

Badminton Stroke Movement Comparison Using Kinect-Based Adaptive Range of Movement Index Technique

Objectives: In this paper, we extended our previous novel lossless compact view invariant compression technique, namely Range of Movement Index (RoMI) by fusing an adaptive module. Methods: An adaptive module is proposed to fuse with the RoMI to elevate the technique to become left-right handed invariant. The module will firstly identify the label of the normalized RoMI value from a particular range in order to determine left or right side. Subsequently, the adaptive mapping functions are utilized to perform left to right or right to left mappings using the identified label. Findings: Generally, badminton players can be categorized into three different handed: mainly right-handed players and left handed-players and rarely the ambidextrous players. In our previous technique, the RoMI can only benchmark or perform computerized badminton movement quality comparison based on the handedness of a badminton player. In specific, the benchmarking mechanism is left-right handed variant, i.e., left-handed player with left-handed player and right-handed player with right-handed player. This limitation will increase the effort to benchmark badminton players’ movement quality with different handedness of badminton player. The proposed adaptive module enables the comparison of computerized stroke movements between different players with different handedness. As such, this new method will identify the labels of the normalized RoMI and performs adaptive mapping to match with the reference handedness to produce a more consistent benchmarking of different handedness badminton players. Improvement: The ability to benchmark different handedness badminton players enables the system to be adopted by a larger range of badminton players and further simplify data collection and analysis procedures. Keywords: Adaptive, Badminton Stroke, Kinect, Movement Comparison, Range of Movement Index (RoMI)

Left-handed skeletally mature baseball players have smaller humeral retroversion in the throwing arm than right-handed players

It is known that the humeral retroversion of baseball players is greater in the throwing arm than in the nonthrowing arm. An investigation measuring dry bone specimens also showed that the right humerus had greater retroversion than the left. Considering these facts, it was hypothesized that humeral retroversion would differ between right- and left-handed players. This study aimed to compare the bilateral humeral retroversion between right- and left-handed skeletally mature baseball players. We investigated 260 (196 right-handed and 64 left-handed) male baseball players who belonged to a college or amateur team. Bilateral humeral retroversion was assessed using an ultrasound-assisted technique (humeral torsion angle [HTA]) as described by previous studies. Analysis of covariance, adjusted for handedness and baseball position, assessed the effect of throwing arm dominance on HTA. In comparison of the throwing arm, HTA was significantly smaller in left-handed (left humerus) than in right-handed (right humerus) players (77° vs. 81°; P < .001). In comparison of the nonthrowing arm, HTA was significantly greater in left-handed (right humerus) than in right-handed (left humerus) players (73° vs. 69°; P < .001). The mean side-to-side difference of HTA was significantly smaller in left-handed than in right-handed players (3° vs. 12°; P < .001). Humeral retroversion of left-handed skeletally mature baseball players was significantly smaller in the throwing arm, greater in the nonthrowing arm, and smaller in side-to-side differences than that of right-handed players. These findings may be key to understanding some of the biomechanical differences between right- and left-handed baseball players.

DETERMINATION OF FEMALE TABLE TENNIS SPORT PERFORMANCE BY SENZOR MOTORIC REACTION TIME

In the sport performance structure of table tennis is sensor motor reaction time one of the most important factors for reaching top-level results, both in males and females groups. In this research we watched 23 female table tennis players from Slovakia; 9 mini cadets (12-13 years), 6 cadets (14-15 years) and 8 juniors (16-18 years). Girls were tested by modified agility test for table tennis players (Vacenovsky &amp; Vencurik, 2013) with machine FITRO Agility check. Thus we gained their sensor motor reaction times. By Mann-Whitney U-test we studied differences between age categories, upper and lower extremities, dominant (forehand) and un-dominant (backhand) side, right and left-handed players. We used significance level p&lt;0.05. In our research we did not confirm expected results that the older groups have shorter sensor motor reaction time. We also expected shorter reaction time of upper extremities comparing lower extremities; this was confirmed, though there was found statistical significant difference only in juniors group. Groups of mini-cadets and cadets have better (shorter) sensor motor reaction time from backhand side, while group of junior is better from forehand side. We also confirmed that left-handed players have slightly shorter reaction time.