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1.
J Sports Sci ; 38(1): 106-113, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31658883

RESUMO

The purpose of this study was to develop an automated method for identifying and classifying change of direction (COD) movements in professional tennis using tracking data. Three sport science and strength and conditioning experts coded match-play footage of nineteen professional tennis players (9 male and 10 female) from the Australian Open Grand Slam for COD of medium and high intensity. A total of 1,494 changes were identified and aligned with 2D player position sampled at 25 Hz based on camera tracking data. Several machine learning classifiers were trained and tested on a set of 1,128 time-motion features. A random forest algorithm was found to have the best out-of-sample performance, classifying medium and high intensity changes with an F1-score of 0.729. This research offers a novel and applicable way for utilising player tracking data and machine learning techniques to automatically identify and classify COD movements in professional tennis.


Assuntos
Aprendizado de Máquina , Destreza Motora/classificação , Tênis/fisiologia , Adulto , Fenômenos Biomecânicos , Comportamento Competitivo/classificação , Comportamento Competitivo/fisiologia , Estudos Transversais , Feminino , Humanos , Masculino , Destreza Motora/fisiologia , Reprodutibilidade dos Testes , Estudos de Tempo e Movimento , Adulto Jovem
2.
Sports Health ; 12(1): 80-87, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31710819

RESUMO

BACKGROUND: The prevalence of musculoskeletal (MSK) conditions is increasing, and although current guidelines for physical activity attempt to combat this, many fail to achieve the recommended targets. The present study sought to investigate whether regular tennis participation is more effective at enhancing MSK function than meeting the current international physical activity guidelines. HYPOTHESIS: Tennis players will display significantly enhanced MSK function when compared with age-matched healthy active nonplayers. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Ninety participants (age range, 18-65 years) took part in this study; there were 43 tennis players (18 men, 25 women) and 47 nonplayers (26 men, 21 women). MSK function was assessed by cluster analysis of 3 factors: (1) electromyographic fatigability of prime movers during handgrip, knee extension, and knee flexion; (2) isometric strength in the aforementioned movements; and (3) body composition measured by bioelectrical impedance analysis. Maximal oxygen uptake was also assessed to characterize cardiorespiratory fitness. RESULTS: Tennis players displayed significantly greater upper body MSK function than nonplayers when cluster scores of body fat percentage, handgrip strength, and flexor carpi radialis fatigue were compared by analysis of covariance, using age as a covariate (tennis players, 0.33 ± 1.93 vs nonplayers, -0.26 ± 1.66; P < 0.05). Similarly, tennis players also demonstrated greater lower extremity function in a cluster of body fat percentage, knee extension strength, and rectus femoris fatigue (tennis players, 0.17 ± 1.76 vs nonplayers, -0.16 ± 1.70; P < 0.05). CONCLUSION: The present study offers support for improved MSK functionality in tennis players when compared with age-matched healthy active nonplayers. This may be due to the hybrid high-intensity interval training nature of tennis. CLINICAL RELEVANCE: The findings suggest tennis is an excellent activity mode to promote MSK health and should therefore be more frequently recommended as a viable alternative to existing physical activity guidelines.


Assuntos
Músculo Esquelético/fisiologia , Tênis/fisiologia , Adolescente , Adulto , Idoso , Composição Corporal , Aptidão Cardiorrespiratória/fisiologia , Análise por Conglomerados , Estudos Transversais , Feminino , Força da Mão , Humanos , Joelho/fisiologia , Masculino , Pessoa de Meia-Idade , Fadiga Muscular/fisiologia , Força Muscular/fisiologia , Consumo de Oxigênio/fisiologia , Adulto Jovem
3.
Zhongguo Ying Yong Sheng Li Xue Za Zhi ; 35(4): 331-335, 2019 Jul 28.
Artigo em Chinês | MEDLINE | ID: mdl-31701717

RESUMO

OBJECTIVE: To investigate the feasibility of applying the measure of energy cost, utilized widely in cyclic sports, in table tennis multi-ball practice. METHODS: Eleven collegiate table tennis players volunteered (18±1 yrs, 177±2 cm, 71±3 kg, approximately 10 yrs' training experience) to participate in one graded exercise test on treadmill, and two step tests (forehand and backhand, 3 min × 6, 35~85 stroke/min). A portable spirometric system and heart rate monitor were utilized for the three trials. Earlobe blood samples were collected and analyzed prior to and post the test. Energy cost was calculated for one stroke at each stroke frequency. RESULTS: The energy cost of loop drive multi-ball practice was decreased with increased stroke frequency (P<0.05). The energy cost of forehand loop drive was higher than backhand, with the difference significant at 35, 45, 55, 65, and 85 stroke·min-1 (P<0.05). The function between energy cost and frequency were y=166.4x-0.731 (R2=0.9731), and y=33.21x-0.392 (R2=0.8423), respectively, where y was energy cost, and x was stroke frequency. CONCLUSION: The measure of energy cost utilized in cyclic sports could be applied to evaluate the energy expenditure in table tennis multi-ball practice of single technique, and indicate the stroke efficiency of table tennis muti-ball practice with different stroke frequencies.


Assuntos
Metabolismo Energético , Tênis/fisiologia , Adolescente , Teste de Esforço , Humanos , Adulto Jovem
4.
Artigo em Inglês | MEDLINE | ID: mdl-31540388

RESUMO

This study aimed to compare the effects of coach encouragement during the on-court tennis training drills (OTDs) on the psychophysiological and performance responses of young tennis players. Twenty-five young male tennis players (14.0 ± 0.3 years of age) performed six bouts of each of the four common OTDs; Star, Suicide, Box and Big X (30:60 s; 1:2 work to rest ratio). The heart rate (HR) and total distance covered were monitored using two portable multivariable integrated 10 Hz GPS monitoring devices during all OTDs, and the rating of perceived exertion (RPE-10) and short form Physical Activity Enjoyment Scale (PACES) values were determined after each OTDs bout. The results demonstrated that OTDs with coach encouragement induced significantly higher psychophysiological and performance responses compared to OTDs without coach encouragement (p < 0.05). The results of this study confirm that coach encouragement improves the intensity, performance and physical enjoyment level during OTDs. These findings might inform training practices in youth tennis players in order to improve tennis performance.


Assuntos
Exercício , Frequência Cardíaca , Esforço Físico , Tênis/fisiologia , Tênis/psicologia , Adolescente , Atletas/psicologia , Atletas/estatística & dados numéricos , Humanos , Masculino
5.
J Sports Sci ; 37(22): 2560-2568, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31379253

RESUMO

Representative Learning Design advocates that practice should simulate the demands of competition. The effectiveness of increased task representativeness to improve serving skill of junior tennis players was assessed after a six-week intervention. Thirty-three participants (15.4 ± 1.9 years of age) were assigned to one of the three groups; "serve only" (participants served to no opponent), "serve return" (participants served to an opponent and hit no extra shots) or "serve +3rd" (participants served to an opponent and hit one extra shot). Using the validated representative practice assessment tool (RPAT) tasks were considered to be low, moderate and high in task representativeness, respectively. Participants hit 56 serves, twice weekly for 6-weeks. Pre and post serving performances were assessed via a skill test and in-situ matchplay using SportsCode and HawkEye ball tracking, respectively. Serve speed, landing locations, serve angle and positional advantage was obtained for 1st and 2nd serves. The relationship between increasing representativeness and increased skill acquisition was not linear, rather different behaviours emerged. For example, when hitting 2nd serves in matchplay, the low and moderate representative groups prioritised speed over placement while the high representative group prioritised placement over speed. Coaches therefore need to carefully individualise representativeness to an athletes' specific needs.


Assuntos
Desempenho Atlético/psicologia , Generalização da Resposta , Destreza Motora/fisiologia , Tênis/psicologia , Adolescente , Desempenho Atlético/fisiologia , Comportamento Competitivo/fisiologia , Feminino , Humanos , Masculino , Tutoria , Análise e Desempenho de Tarefas , Tênis/fisiologia
6.
PLoS One ; 14(4): e0214819, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30986241

RESUMO

Grunting in tennis is a widespread phenomenon and whether it influences opponents' predictions of ball trajectory-and if so, why-is subject of ongoing debate. Two alternative hypotheses have been proposed to explain why grunting may impede opponents' predictions, referred to as the distraction account (i.e., grunts capture attentional resources necessary for anticipation) and the multisensory integration account (i.e., auditory information from the grunt systematically influences ball trajectory prediction typically assumed to rely on visual information). To put these competing hypotheses to test, in the current study we presented tennis players with a series of temporally occluded video clips of tennis rallies featuring experimentally amplified, attenuated, or muted grunting sounds. Participants were asked to predict the ball landing position. Results indicated that higher grunt intensities yielded judgments of longer ball trajectories whereas radial prediction errors were not affected. These results are clearly at odds with the distraction account of grunting, predicting increased prediction errors after higher intensity grunts. In contrast, our findings provide strong support for the multisensory integration account by demonstrating that grunt intensity systematically influences judgments of ball trajectory.


Assuntos
Desempenho Atlético/psicologia , Comunicação não Verbal/psicologia , Tênis/psicologia , Desempenho Atlético/fisiologia , Percepção Auditiva/fisiologia , Feminino , Humanos , Julgamento/fisiologia , Masculino , Comunicação não Verbal/fisiologia , Som , Tênis/fisiologia , Gravação em Vídeo
7.
J Sports Sci ; 37(17): 1962-1971, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31030639

RESUMO

This study investigated split-step timing when returning serves and whether this timing is related to neuromechanical capabilities in world-class tennis players. In Experiment 1, the split-step timing of four groups of world-class players (male and female ATP/WTA seniors, and ITF juniors) was measured on court when returning serves of the same level players. The four groups initiated the split-step at a similar time, starting around the time ball-racket contact in the serve stroke and landed when early ball-flight information was available. In Experiment 2, the neuromechanical capabilities (leg stiffness and vertical jump performance) of a group of world-class players and three groups of less-skilled tennis players were examined. The results showed an increase in leg stiffness with an increase in the level of expertise. A cross-experiment analysis in world-class male players (ATP/ITF, n = 10) revealed that the timing of initial foot movement was significantly correlated with the leg stiffness (r2 = 0.54), with later lateral step after the serve in the players who had higher stiffness. The findings support the hypothesis that world-class tennis players adapt perceptual-motor control on the basis of their neuromechanical capabilities and maximise the time before initiating their interceptive action to rely on more reliable information.


Assuntos
Desempenho Atlético/fisiologia , Extremidade Inferior/fisiologia , Tênis/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos , Feminino , Pé/fisiologia , Humanos , Masculino , Tempo , Adulto Jovem
8.
Medicina (Kaunas) ; 55(4)2019 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-30965645

RESUMO

Background and objectives: The popularity of table tennis has increased globally. As a result, the biomechanical movement patterns in the lower limb during table tennis have attracted extensive attention from coaches, scientists and athletes. The purpose of this study was to compare the differences between the long and short chasse steps in table tennis and evaluate risk factors related to injuries in the lower limb. Materials and Methods: Twelve male elite athletes performed forehand topspin strokes with long and short chasse steps in this study, respectively. The kinematics data of the lower-limb joints were measured by a Vicon motion analysis system. The electromyograms (EMG) of six lower-limb muscles were recorded using a myoelectricity system. Results: The key findings were that the angle change rate of the ankle in the long chasse step was faster with a larger range of motion (ROM) in the coronal and transverse planes. The hip was also faster in the sagittal and transverse planes but slower in the coronal plane compared with the short chasse step. In addition, the vastus medialis (VM) was the first activated muscle in the chasse step. Conclusions: The hip and ankle joints in the long chasse step and the knee joint in the short chasse step have higher susceptibility to injury. Moreover, tibialis anterior (TA), vastus medialis (VM) and gastrocnemius (GM) should be sufficiently stretched and warmed prior to playing table tennis. The results of this study may provide helpful guidance for teaching strategies and providing an understanding of potential sport injury mechanisms.


Assuntos
Desempenho Atlético/fisiologia , Extremidade Inferior/fisiologia , Tênis/lesões , Tênis/fisiologia , Adulto , Traumatismos do Tornozelo , Articulação do Tornozelo/fisiologia , Atletas , Fenômenos Biomecânicos , Eletromiografia , Lesões do Quadril , Articulação do Quadril/fisiologia , Humanos , Traumatismos do Joelho , Articulação do Joelho/fisiologia , Masculino , Músculo Esquelético/fisiologia , Músculo Quadríceps/fisiologia , Amplitude de Movimento Articular/fisiologia , Fatores de Risco , Exercício de Aquecimento/fisiologia , Adulto Jovem
9.
J Back Musculoskelet Rehabil ; 32(4): 629-638, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30614792

RESUMO

BACKGROUND: Although low back pain (LBP) is known to be multi-factorial, certain studies have suggested that a deficit in hip extension and rotation range of motion (ROM) may be associated with LBP in athletes. OBJETIVE: The purpose of this study was to compare hip extension and rotation ROMs in elite tennis players with and without a history of LBP. METHODS: Forty-two male and 22 female young elite tennis players completed this study. Participants were divided into two groups: (1) 32 with history of LBP and (2) 32 without history of LBP. Descriptive measures of passive hip extension and rotation ROMs of the dominant and non-dominant limbs were taken. Active hip rotation ROMs were also assessed. Magnitude-based inferences on differences between groups and legs were made by standardizing differences. RESULTS: The inter-group statistical analysis reported no significant differences (p> 0.05; trivial effect with a probability higher than 95%; d⩽ 0.4) in any ROM measure analyzed. Further, neither LBP group nor control group reported significant bilateral or side-to-side differences (p> 0.05; trivial effect with a probability higher than 99%; d< 0.3) between legs regarding hip extension and rotation ROM measures. CONCLUSION: No relationship between hip extension and rotation ROM and history of LBP was found.


Assuntos
Articulação do Quadril/fisiopatologia , Dor Lombar/fisiopatologia , Tênis/fisiologia , Adolescente , Atletas , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Amplitude de Movimento Articular , Rotação , Adulto Jovem
10.
Int J Sports Physiol Perform ; 14(7): 887-893, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-30569784

RESUMO

PURPOSE: This study aimed to determine whether the game activity and physiological responses of young tennis players differed depending on the session of play (e.g., morning (MOR) vs. afternoon (AFT)) and the final match outcome (e.g., winners vs. losers), during a simulated competition with two matches on the same day. METHODS: Twelve well-trained male tennis players (14.5±0.8 years) took part in a simulated competition of two 3-set matches separated by 3 h. All the matches were video-recorded and the participants were monitored using 10 Hz global positioning (GPS) units including a heart-rate (HR) monitor. Effect size (ES) statistics were used to investigate the magnitudes of the differences. RESULTS: During the AFT matches, in absolute terms, players covered longer total distance (ES=moderate), ran more distance between 0 and ≤ 4m·s-1 (ES=small-to-large) compared to MOR matches. Total duration was also longer (ES=large) in the AFT, where the rest time between rallies was also longer (ES=very large). HR was similar during both AFT and MOR matches, but higher rates of perceived exertion (RPE) (ES=moderate) were reported in the AFT. Only peak running velocity was observed to be likely higher for losers compared to winners (ES=small). CONCLUSIONS: Game activity and physiological responses of young tennis players differ when two consecutive matches are played on the same day. These data might help to elucidate the need for specific pre-competition training loads and/or in-between match/session recovery strategies when facing overloaded competitions.


Assuntos
Desempenho Atlético/fisiologia , Tênis/fisiologia , Adolescente , Atletas , Comportamento Competitivo , Sistemas de Informação Geográfica , Frequência Cardíaca , Humanos , Masculino , Esforço Físico , Gravação em Vídeo
11.
Q J Exp Psychol (Hove) ; 72(5): 1131-1140, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-29792565

RESUMO

This study was aimed at determining how the visual information of an end-effector (racket) and the intermediate extremity (arm) of a tennis server contribute to the receiver's anticipatory judgement of ball direction. In all, 15 experienced tennis players and 15 novice counterparts viewed a spatially occluded computer graphics animation of a tennis serve (no-occlusion, racket-occlusion, and body-occlusion) and made anticipatory judgements of ball direction on a visual analogue scale (VAS). The patterns of the serve motions were generated by a simulation technique that computationally perturbs the rotation speed of the selected racket-arm joint (forearm pronation and elbow extension) on a captured serve motion. The results suggested that the anticipatory judgements were monotonically attuned with the perturbation rate of the forearm pronation speed excepting under the conditions of the racket-occlusion model. Although such attunements were not observed in the elbow perturbation conditions, the results of correlation analysis indicated that the residual information in the spatially occluded models had a similar effect to the no-occlusion model within the individual experienced participants. The findings support the notion that end-effector (racket) provides deterministic cues for anticipation, as well as imply that players are able to benefit from the relative motion of an intermediate extremity (elbow extension).


Assuntos
Antecipação Psicológica/fisiologia , Braço/fisiologia , Julgamento/fisiologia , Percepção de Movimento/fisiologia , Percepção Espacial/fisiologia , Tênis/fisiologia , Adulto , Gráficos por Computador , Feminino , Humanos , Masculino , Mascaramento Perceptivo/fisiologia , Adulto Jovem
12.
J Sports Sci ; 37(7): 755-761, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30332916

RESUMO

This study evaluates whether high levels of executive function predict competition results 18 months later in junior tennis players. Forty junior tennis players (20 girls, 20 boys; 9-15 years old) who regularly participate in prefecture tennis tournaments were recruited. All participants underwent executive function evaluations (the Design Fluency Task) in July 2015 and their prefecture junior rankings in August 2015 and February 2017 were recorded. As a result, after controlling for age and gender, the future ranking (February 2017) was significantly predicted by performance in the Design Fluency Task (ß = -.30, p = .02; ΔR2 = .08), whereas the prediction for August 2015 rank as the baseline was not significant (ß = -.19, p = .17; ΔR2 = .03). After controlling for age, gender, and ranking in the baseline, the change in ranking was significantly predicted by performance in the Design Fluency Task (ß = -.14, p = .02; ΔR2 = .02). This suggests that childhood executive function may play a significant role in success later in life. This study highlights how executive function predicts future success in a specific sport; as such, supporting the development of executive function may contribute to higher competition results.


Assuntos
Logro , Desempenho Atlético/fisiologia , Desempenho Atlético/psicologia , Comportamento Competitivo/fisiologia , Função Executiva , Tênis/fisiologia , Tênis/psicologia , Adolescente , Fatores Etários , Criança , Feminino , Seguimentos , Humanos , Masculino , Fatores Sexuais , Análise e Desempenho de Tarefas
13.
J Sports Sci ; 37(6): 613-620, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30317921

RESUMO

In table tennis the follow-through action after a shot is an important part of skill execution. In this experiment, we aimed to extend literature around the contextual interference effect by investigating whether the way the follow-through is organised in practice affects learning of the backhand shot in table tennis. Thirty unskilled participants were allocated to blocked-variable practice, random-variable practice or a control-constant group and aimed backhand shots towards a target following ball projection from a machine. Each group completed these shots in a pre-test, a training phase with follow-through manipulations, a post-test, and a retention test. The random-variable group improved their shot accuracy from pre-test to post-test and from pre-test to retention test (both P < 0.01, d = 1.03), whereas neither the blocked-variable nor the control-constant group displayed any change in shot accuracy. Practising the follow-through in a random-variable fashion enhanced learning of the preceding shot compared with blocked-variable practice or no follow-through instructions. The benefits of learning motor skills under conditions of high contextual interference also apply to how follow-through actions are organised. The findings are valuable to coaches and suggest that instructions related to the follow-through action should be considered as well as the primary skill itself.


Assuntos
Desempenho Atlético , Aprendizagem , Destreza Motora , Tênis/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
14.
J Sports Sci ; 37(7): 726-734, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30319029

RESUMO

The purpose of this study was to explore the processes associated with successful on-court movement in professional tennis. To date, research has only provided generalised insight into the physical demands of tennis movement and the requisite physical skills. Data were collected through semi-structured interviews with 15 international tennis and/or strength and conditioning coaches involved in the development of tennis-specific movement in professional men's and women's tennis. A descriptive, qualitative approach was adopted, with interviews transcribed verbatim and analysed using an inductive to deductive thematic analysis. The highlighted ideas and concepts enabled the dynamic construction of higher-order themes representative of "good" tennis movers, alongside the conceptual development of a common movement "goal" or "outcome". The established higher-order themes portrayed three "styles" of "good" movers in modern professional tennis: those who were "fast" around the court, those who "read the play" well, and those who were "efficient" in their movement. The established themes provide a framework for interpreting and categorising the movement of professional tennis players as well as its underpinning skill.


Assuntos
Desempenho Atlético/fisiologia , Mentores/psicologia , Destreza Motora/fisiologia , Movimento , Percepção , Tênis/fisiologia , Comportamento Competitivo/fisiologia , Eficiência/fisiologia , Feminino , Pé/fisiologia , Humanos , Entrevistas como Assunto , Masculino
15.
Eur J Sport Sci ; 19(6): 765-773, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30417752

RESUMO

Waiter's serve (WS) is a specific tennis serve posture frequently observed in young players, and commonly considered as a technical error by tennis coaches. However, biomechanical impact of WS is unknown. The aims of this study were to identify the potential consequences of WS in young elite players relating to performance and injury risk, and to explain the kinematic causes of WS. Serve of 18 male junior elite players (Top 10 national French ranking, aged 12-15 years) was captured with a 20 camera, 200 Hz VICON MX motion analysis system. Depending on their serve technique, the players were divided into two groups (WS versus Normal Serve [NS]) by experienced coaches. Injury data were collected for each player during a 12-month-period following the motion capture. Normalized peak kinetic values of the dominant arm were calculated using inverse dynamics. In order to explain WS posture, upper limb kinematics were calculated during the cocking and the acceleration phases of the serve. Shoulder internal rotation torque, wrist proximal and anterior forces (P < .05) and elbow varus torque (P < .01) were significantly higher in WS group, with no difference from NS group concerning serve velocity. Moreover, significant lower shoulder abduction and higher wrist extension (P < .05) were observed for WS players during the cocking phase. Even if no significant difference was found between groups concerning injuries, higher upper limb joint loads suggested WS could be considered as pathomechanical in young elite players and could lead to upper limb joint injuries.


Assuntos
Traumatismos em Atletas/epidemiologia , Transtornos Traumáticos Cumulativos/epidemiologia , Postura , Tênis/fisiologia , Extremidade Superior/fisiologia , Adolescente , Braço , Fenômenos Biomecânicos , Criança , Cotovelo , Humanos , Masculino , Ombro , Tênis/lesões , Torque , Punho
16.
J Sports Sci ; 37(9): 1011-1020, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30380360

RESUMO

The aims of this study were to examine the effect of different environmental constraints on kinematic multi-segment coordination patterns during the service and its coordination with service time variability. Ten expert tennis players (Age: 34.1 ± 5.3) volunteered to take part in this study. Participants served 30 times in 3 different conditions: control, target and opposition. The order of conditions was counterbalanced between participants. A wireless 3D motion capture system (STT Co, Spain) was used to measure 7 joint motions, with a 17 degrees of freedom biomechanical model created to capture the entire service action. Results of the principal component analysis showed that 4 synergies were created; however, their roles were changed relative to the perception of the environment. The results of repeated-measures analysis of variance did not show any significant difference on total variance and individual principal components between conditions; however, one synergy pattern significantly predicted the service time variability in both control and opposition conditions. In conclusion, the findings demonstrated that expert performers reduce the joint dimensionality by creating functional synergies in different phases of service and adapt the service action according to the perception of the environment.


Assuntos
Meio Ambiente , Desempenho Psicomotor , Tênis/psicologia , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Tênis/fisiologia
17.
Eur J Sport Sci ; 19(4): 471-479, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30362890

RESUMO

Table tennis players often execute one-step, side-step or cross-step to move to an appropriate position for topspin forehand. However, to our knowledge, no studies have investigated the footwork effects on lower-limb kinetics and kinematics, which are related to playing performance and injury prevention. This study examined the ground reaction forces, joint kinetics and in-shoe plantar pressure distribution during topspin forehand with three typical footwork patterns. Fifteen male table tennis players performed cross-court topspin forehands in one-step, side-step and cross-step. Force plate, motion capturing, and instrumented insole systems were used to measure ground reaction force, joint moments and plantar pressure variables. One-way ANONA with repeated measures was performed to determine any significant differences between footwork. Results indicated that participants exhibited significantly higher ground reaction force loadings, knee flexion angle, knee moment, ankle inversion and moment during side-step and cross-step compared with one-step footwork condition (p < .01). Plantar pressure data indicated that the significantly higher peak pressure were observed in the total foot, toe, 1st, 2nd and 5th metatarsal regions during side-step and cross-step (p < .01). Additionally, cross-step had induced higher peak pressure in medial midfoot and heel regions than one-step and higher peak pressure in total and 1st metatarsal regions than side-step (p < .01). These results suggest that foot orthotic designs should consider the stronger emphasis on those high-pressured areas and that the differential joint and plantar loadings in side-step and cross-step may provide useful insights to injury mechanism and training protocol development.


Assuntos
Pé/fisiologia , Pressão , Tênis/fisiologia , Adulto , Tornozelo , Fenômenos Biomecânicos , Calcanhar , Humanos , Joelho , Masculino , Movimento , Amplitude de Movimento Articular , Sapatos , Adulto Jovem
18.
Eur J Sport Sci ; 19(7): 902-912, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30551731

RESUMO

The differences between the racket-arm acceleration mechanisms during open and square stance forehand groundstrokes in tennis were examined by quantifying the mechanical work done on the racket arm. We studied 13 advanced tennis players as they performed these strokes at maximum effort and calculated the work using inverse dynamics. The racket head speed was similar between the open and square stances. In the open stance, the lack of weight shifting towards the hitting direction resulted in a lower velocity for the shoulder joint centre in the hitting direction than in the square stance, and less work was done by the shoulder joint force in the hitting direction in the open stance than in the square stance (0.30 ± 0.11 J·kg-1 vs. 0.38 ± 0.16 J·kg-1; p = 0.005). However, in the open stance, the torso rotated more towards the hitting direction and had more upward acceleration, which resulted in more work done by the sideways and upward shoulder joint forces than in the square stance (sideways: 0.07 ± 0.09 J·kg-1 vs. 0.05 ± 0.09 J·kg-1, p = 0.046; upward: 0.08 ± 0.09 J·kg-1 vs. 0.04 ± 0.07 J·kg-1, p = 0.002). Thus, the greater work done by the sideways and upward shoulder joint forces compensated for the lesser work done by the shoulder joint force in the hitting direction in the open stance. In both stances, mainly the horizontal flexion torque and internal rotation torque at the shoulder increased the energy of the racket arm.


Assuntos
Articulação do Ombro/fisiologia , Tênis/fisiologia , Aceleração , Adulto , Humanos , Masculino , Amplitude de Movimento Articular/fisiologia , Rotação , Torque
19.
J Sports Sci ; 37(1): 108-121, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29889615

RESUMO

The aim of this systematic review is to provide an overview of outcome measures and instruments identified in the literature for examining technical and tactical skills in tennis related to performance levels. Such instruments can be used to identify talent or the specific skill development training needs of particular players. Searches for this review were conducted using the PubMed, Web of Science, and PsycInfo databases. Out of 733 publications identified through these searches, 40 articles were considered relevant and included in this study. They were divided into three categories: (1) technical skills, (2) tactical skills and (3) integrated technical and tactical skills. There was strong evidence that technical skills (ball velocity and to a lesser extent ball accuracy) and tactical skills (decision making, anticipation, tactical knowledge and visual search strategies) differed among players according to their performance levels. However, integrated measurement of these skills is required, because winning a point largely hinges on a tactical decision to perform a particular stroke (i.e., technical execution). Therefore, future research should focus on examining the relationship between these skills and tennis performance and on the development of integrated methods for measuring these skills.


Assuntos
Desempenho Atlético/fisiologia , Destreza Motora/fisiologia , Tênis/fisiologia , Antecipação Psicológica , Tomada de Decisões , Humanos , Tênis/psicologia , Percepção Visual/fisiologia
20.
J Sports Sci ; 37(1): 100-107, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29893161

RESUMO

The purpose of this study was to create a valid and reliable assessment scale for the evaluation of three basic tennis strokes (forehand, backhand, serve) for 6-12-year-old tennis players, named the Tennis Rating Score for Children (TRSC). Altogether 60 players (21: forehand, 22: backhand, 17: serve) were video recorded (30 frames per second) while performing three main tennis strokes and later evaluated using the TRSC by five tennis trainers at Day 1 and Day 7. Agreement between days and raters was examined using the intraclass correlation coefficients (ICC). A Pearson's correlation was calculated to determine convergent validity (score related to participant's level of experience). The reliability between raters was very high for all three main strokes (ICCFOREHAND = 0.874; ICCBACKHAND = 0.877; ICCSERVE = 0.877). The intra-rater test-retests ICCs were also very high (ICCFOREHAND = 0.885; ICCBACKHAND = 0.891; ICCSERVE = 0.887). A large (rFOREHAND = 0.660) and very large (rBACKHAND = 0.730; rSERVE = 0.772) Pearson's correlations were found between all the ratings and the level of experience. The TRSC is shown to be highly reliable and valid when assessing technical skills in novice players, when compared to actual assessment from coaching experts; this tool may be helpful for tennis coaches to make a more objective diagnostic of the technical level of young tennis players.


Assuntos
Destreza Motora/fisiologia , Análise e Desempenho de Tarefas , Tênis/fisiologia , Fenômenos Biomecânicos , Criança , Humanos , Reprodutibilidade dos Testes , Gravação em Vídeo
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