Racket Velocity Research Articles

Kinematic characterization of backhand stroke accuracy in squash based on kinematic variables between two different skill levels-a preliminary cross-sectional study.

The aim of this study was to compare differences in shot placement and accuracy between national and international level squash players. Squash is a technically demanding sport and understanding the biomechanical characteristics of athletes at different levels is important for developing effective training strategies. The study used a three-dimensional motion analysis system, a high-speed video camera, and a professional tee for biomechanical testing. Participants included national and international level squash players. The kinematic characteristics of the shoulder, elbow, and wrist joints of the upper extremity for backhand strokes, as well as the accuracy of the strokes, were analyzed to compare the differences between the two groups of athletes in terms of stroke posture and accuracy. The kinematic analysis of the backward backhand stroke revealed that national squash players showed significant differences compared to international players in several key parameters. Specifically, national players had significantly greater trunk flexion (P=0.018) and less shoulder medial rotation (P=0.027). They also had lower racket velocity in the X-direction (P=0.043). However, there were no significant differences in trunk lateral flexion (P=0.487), trunk rotation (P=0.293), shoulder extension/flexion (P=0.396), elbow flexion/extension (P=0.818), wrist flexion/extension (P=0.177), wrist rotation (P=0.476), racket pitch (P=0.112), racket velocity in the Y-direction (P=0.587), or racket velocity in the Z-direction (P=0.327). Additionally, data for racket yaw, racket roll, and racket Vx were not provided with significant values, indicating that these parameters do not show significant differences. International level players outperformed national level players in squash stroke accuracy and control. Key kinematic factors influencing accuracy include trunk forward flexion, shoulder abduction, shoulder internal rotation, and racket angles. The study recommends that coaches design training to enhance technical details and positional control to improve squash performance.

Are there kinematic and kinetic parameters correlated with racket velocity during the tennis serve? A preliminary comparison between a slow and a fast serve for performance improvement.

The tennis serve is a complex motion with numerous rotations which are important to manage for performance. The main aim of this study was to investigate kinematic parameters, including the evolution of the center of gravity, and kinetic parameters correlated with racket velocity over all phases of the tennis serve. The secondary objective was to find out which of the correlated parameters differed between a slow and a fast serve. The advantage of such an approach would be to propose biomechanical parameters that coaches and teachers could use to optimize performance or learn how to serve. Quantitative analysis was carried out on 5 flat serves performed by four ranked players using an optoelectronic system (82 markers located on whole body and racket) composed of 10 infrared cameras (150 Hz) and two force platforms (750 Hz). A descriptive statistical analysis highlighted 11 very large and almost perfect correlations with racket velocity: vertical ground reaction force of back foot in release backward, trunk axial rotation during loading phase, back and front knee flexions, dominant shoulder and hip mediolateral rotation during cocking phase, and center of gravity vertical velocity, dominant shoulder medial rotation velocity, dominant elbow flexion, trunk flexion/extension and axial rotation during acceleration phase. Differences were observed for some of the correlated parameters between slow and fast serve. Consequently, all these correlated kinematic and kinetics parameters constitute information that coaches, instructors and athletes can use to improve, optimize or teach the tennis serve.

Relationships Between Force-Time Curve Variables and Tennis Serve Performance in Competitive Tennis Players.

Fourel, L, Touzard, P, Fadier, M, Arles, L, Deghaies, K, Ozan, S, and Martin, C. Relationships between force-time curve variables and tennis serve performance in competitive tennis players. J Strength Cond Res 38(9): 1667-1674, 2024-Practitioners consider the role of the legs in the game of tennis as fundamental to achieve high performance. But, the exact link between leg actions and high-speed and accurate serves still lacks understanding. Here, we investigate the correlation between force-time curve variables during serve leg drive and serve performance indicators. Thirty-six competitive players performed fast serves, on 2 force plates, to measure ground reaction forces (GRF). Correlation coefficients describe the relationships between maximal racket head velocity, impact height, and force-time curve variables. Among all the variables tested, the elapsed time between the instants of maximal vertical and maximal anteroposterior GRF ( r = -0.519, p < 0.001) and the elapsed time between the instant of maximal anteroposterior GRF and ball impact ( r = -0.522, p < 0.001) are the best predictors of maximal racket velocity. Maximal racket head velocity did not significantly correlate with the mean or maximal vertical GRF or with the mean or maximum rate of vertical force development. The best predictor for impact height is the relative net vertical impulse during the concentric phase ( r = 0.772, p < 0.001). This work contributes to a better understanding of the mechanical demands of tennis serve motion and gives guidelines to improve players preparation and performance. Trainers should encourage their players to better synchronize their upward and forward pushing action during the serve to increase maximal racket head velocity. Players should also aim to improve their relative net vertical impulse to increase impact height through strength training and technical instructions.

Kinematics of the Tennis Serve Using an Optoelectronic Motion Capture System: Are There Correlations between Joint Angles and Racket Velocity?

The serve is the most important stroke in tennis. It is a complex gesture consisting of numerous rotations with a wide amplitude, which are important to manage for performance. The aim of this study was to investigate whether correlations exist between joint kinematic parameters and racket velocity. A quantitative kinematics analysis of four ranked players (two boys and two girls) was carried out using an optoelectronic system composed of 10 cameras (150 Hz). Five flat serves per player were analyzed. Eighty-two markers were located across the 15 body segments and on the racket. A descriptive statistical analysis including a correlation analysis was carried out between joint angles and racket kinematic parameters (vertical position, velocity, and acceleration) during the cocking and acceleration phases. Ten very high (0.7 < r < 0.9) and three almost perfect (r > 0.9) correlations were found. Shoulder and hip axial rotations, knee flexion, and trunk extension were correlated linearly with racket vertical position and velocity during the cocking phase. For the acceleration phase, elbow flexion, trunk flexion/extension, and trunk axial rotation were linked to racket kinematics. Some of these parameters showed differences between slow and fast serves. These parameters, which are involved in transmitting ball velocity, are important to consider for tennis players and coaches in training programs, education, and performance enhancement.

Upper Extremity Muscle Activation during Drive Volley and Groundstroke for Two-Handed Backhand of Female Tennis Players.

Drive volley is one of the essential backhand stroke technique trends seen in recent women's tennis competitions. Although movements of the drive volley and groundstroke are similar, activation of the internal muscles vary due to different incoming ball conditions. Most previous studies only focused on the groundstroke, however. The current study investigates the different muscle activation patterns in the upper extremity muscle during the two-handed backhand drive volley as well as the groundstroke for female tennis players. Ten elite female tennis players were measured in the muscle activation of the flexor carpi radialis (FCR), extensor carpi radialis (ECR), biceps brachii (BB), and triceps brachii (TB) from both upper extremities. Racket-head speed at impact, swing duration of each phase, and racket-head average velocity in both strokes were also recorded. Significant differences were found between the drive volley and groundstroke in the velocity profile of racket tip, swing duration of each phase (preparation, early follow-through, and late follow-through), activation patterns of upper extremity muscles, and flexor/ extensor ratios of wrist and elbow in both upper extremities. Different racket trajectory strategies were also observed between the two strokes, with greater horizontal racket velocity recorded in the groundstroke but greater vertical velocity in the drive volley. ECR and TB muscle activation during the drive volley preparation phase was greater than the groundstroke when completing a quicker backswing. In the early acceleration phase, the greater FCR leading arm activation in the drive volley assisted wrist stabilization in preparation for impact. In the late follow-through phase, less TB leading arm activity and higher ECR trailing arm activity in the drive volley showed more forward compression movement in racket contact with the ball. As it is essential for the drive volley to complete a quicker backswing and to increase shot efficiency at the end of the forward movement, coaches should consider the two strokes' muscle activation and technique differences to enhance specific techniques and fitness training programs.

Evaluation of Upper Limb Joint Contribution to Racket Head Speed in Elite Tennis Players Using IMU Sensors: Comparison between the Cross-Court and Inside-Out Attacking Forehand Drive.

This study aimed to quantify and compare the upper limb angular kinematics and its contributions to the racket head speed between the cross-court (CC) and inside-out (IO) attacking tennis forehand of elite tennis players in a competitive environment. A new approach was used to study the forehand drive with mini-inertial sensors of motion capture to record the kinematic data. Six strokes in each direction per participant (72 shots in total) were chosen for analysis. Upper limb kinematics were calculated in the Visual 3D platform (Visual 3D Professional V5.01.21, C-motion, Germantown, MD, USA). The method used to calculate the upper limb’s contributions was performed with MATLAB software and used the segment’s (upper arm, forearm and hand) angular velocities and their respective displacement vectors obtained through the inertial sensors. Upper limb kinematics demonstrated a higher shoulder rotation in the IO direction with significant differences at the end of the backswing, which could be a key factor in distinguishing the two directions of the shot. Results also demonstrated that the horizontal flexion of the upper arm (around the shoulder joint) was primarily responsible for the racket velocity in the anteroposterior direction (48.1% CC and 45.2% IO), followed by the extension of the forearm (around the elbow joint) (17.3% CC and 20.9% IO) and the internal rotation of the upper arm (around the shoulder joint) (15.6% CC and 14.2% IO). No significant differences were shown in the contributions of upper limbs to the racket head velocity between the two directions of the shot. Tennis coaches and players should develop a specific training programme to perform higher angular velocities in these specific joint rotations.

An analysis of whole-body kinematics, muscle strength and activity during cross-step topspin among table tennis players

ABSTRACT This study examined the differences of muscle strength, electromyography (EMG) and whole-body kinematics during maximum cross-step table tennis topspin between advanced and intermediate players. Ten advanced and ten intermediate players performed both voluntary isokinetic contraction test and forehand topspin strokes with maximum-effort towards cross-court target zone. The results indicated that advanced players generated significantly greater maximum racket speeds during forward swing phase (P < 0.05). At the instant of the topspin stroke, significantly smaller shoulder horizontal flexion and elbow flexion angles, but larger joint angular velocities in advanced players (P < 0.05). Moreover, advanced players exhibited longer muscle firing duration of anterior deltoid and biceps brachii as well as higher root mean squares and EMG integrals of the abdominal external oblique, anterior deltoid and biceps brachii muscles than the intermediate players (P < 0.05). Furthermore, the isokinetic results showed higher shoulder abduction/adduction, hip flexion/extension and knee flexion torques at fast speed (240°/s) and higher elbow flexion torque at medium speed (120°/s) in advanced players (P < 0.05). The findings suggest that higher activation of the deltoid, biceps and abdominal external oblique muscles as well as larger muscle strength under higher speed conditions would be the plausible key factors to maximise racket and joint angular velocities in forehand topspin.

The Effects of Knee Flexion on Tennis Serve Performance of Intermediate Level Tennis Players.

This study aimed to investigate the effects of knee flexion during the preparation phase of a serve on the tennis serve performance, using inertial sensors. Thirty-two junior tennis players were divided into two groups based on their maximum knee flexion during the preparation phase of serve: Smaller (SKF) and Greater (GKF) Knee Flexion. Their racket velocity, racket height, and knee extension velocity were compared during the tennis serve. Inertial sensors tracked participants’ shank, thigh, and racket motions while performing five first, flat, and valid serves. Knee flexion was analysed during the preparation phase of serve, knee extension velocity after this phase, racket velocity just before ball impact, and racket height at impact. Pre-impact racket velocity (mean difference [MD] = 3.33 km/h, p = 0.004) and the knee extension velocity (MD = 130.30 °/s, p = 0.012) were higher in the GKF than SKF; however, racket impact height was not different between groups (p = 0.236). This study’s findings support the importance of larger knee flexion during the preparation phase of serve-to-serve performance. This motion should be seen as a contributor to racket velocity.

Influence of scapular dyskinesis, kinesiotaping and fatigue on tennis serve performance

ABSTRACTThe objective of this study was to assess the influence of scapular kinesiotaping and scapular muscle fatigue on tennis performance in dyskinetic players, with regard to racket velocity and the accuracy of the serve. Fifteen tennis players with scapular dyskinesis on the dominant side were assessed when performing 15 serves in three different conditions: standard condition, with kinesiotaping and with scapular fatigue. Racket velocity was estimated using a three-dimensional optoelectronic system. Accuracy was measured using a 1 m2 scoring system. Considering all population, kinesiotaping did not significantly increased racket velocity but in decreased until 45% the accuracy of the serve. As to scapular muscle fatigue, it significantly decreased both racket velocity (4%) and accuracy of the serve (until 55%) in all the sample. So, scapular kinesiotaping would not be recommended to increase performance in dyskinetic tennis players, especially if they are not used to. Scapular muscle fatigue, by disrupting kinetic chain transfer, lead to a decrease in tennis serve performance. In view of the important numbers of serves during a tennis match, improving specific endurance of scapular stabilisers muscles would have an interest in this population to maintain performance during a match.

The kinematic differences between skill levels in the squash forehand drive, volley and drop strokes

ABSTRACT Knowledge of the kinematic differences that separate highly skilled and less-skilled squash players could assist the progression of talent development. This study compared trunk, upper-limb and racket kinematics between two groups of nine highly skilled and less-skilled male athletes for forehand drive, volley and drop strokes. A 15-camera motion analysis system recorded three-dimensional trajectories, with five shots analysed per participant per stroke. The highly skilled group had significantly (p < 0.05) larger forearm pronation/supination range-of-motion and wrist extension angles at impact than the less-skilled. The less-skilled group had a significantly more “open” racket face and slower racket velocities at impact than the highly skilled. Rates of shoulder internal rotation, forearm pronation, elbow extension and wrist flexion at impact were greater in the drive stroke than in the other strokes. The position of the racket at impact in the volley was significantly more anterior to the shoulder than in the other strokes, with a smaller trunk rotation angular velocity. Players used less shoulder internal/external rotation, forearm pronation/supination, elbow and wrist flexion/extension ranges-of-motions and angular velocities at impact in the drop stroke than in the other strokes. These findings provide useful insights into the technical differences that separate highly skilled from less-skilled players and provide a kinematic distinction between stroke types.

Contribution of the arm segment rotations towards the horizontal ball and racket head velocities during forehand long shot and drop shot services in table tennis

ABSTRACT Service is assumed important in table tennis because an effective service may allow the serving player to control over the game; hence, the aim of this study was to determine the contribution of arm segment rotations towards ball impact during forehand service. Sixteen shake-hand grip collegiate table tennis athletes had participated in the study. It was revealed that by increasing the radial deviation angular velocity will increase the ball and racket velocities during drop shot service. Furthermore, it was revealed that increasing the wrist palmar flexion and radial deviation will enhance the racket velocity at impact during long shot service. However, it was recommended to the players not to concern on racket speed and arm segment rotations during contact phase as it could not accelerate the ball at impact during long shot service. Although it was the same forehand service, different length of flight ball lead to different contributions of arm segment rotations towards ball impact. The present findings highlight several better postures to increase racket and ball speed at impact during forehand long shot and drop shot services among advanced and intermediate players. Other ranked players may find this study useful as a fundamental understanding on kinematics serving arm.

Comparison of hip joint mechanical energetics in table tennis forehand and backhand drives: a preliminary study

Hip joints are highly involved in table tennis. Some authors found both pelvic angular velocity and hip joint torques are related to the racket velocity. Others have also demonstrated how some of the best players have higher ranges of motion of the lower-limb joints. Therefore, the mechanical work generated by the playing-side-hip can be seen as indicator of the playing intensity associated with different strokes. The aim of this study was to quantify the hip joint mechanical work and power during four classical strokes. Motion capture acquisitions were performed on two international players. A biplanar radiographic acquisition was also performed to personalize the biomechanical model. Hip joint velocity and torques were calculated on the dominant side, allowing mechanical power and work to be calculated between the end of backswing and the ball impact. The highest level of mechanical work from the hip joint was found for forehand drive against backspin and forehand topspin drive with pivot. A backhand drive required the lowest hip mechanical work, and the forehand drive against topspin was found to be intermediate. The lower work required from the backhand stroke makes it suitable as a waiting stroke.

Directionally compensated mechanical work provided by the shoulder leads to similar racket velocities during open and square stance forehand groundstrokes in tennis

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.

The Evaluation of Changes of Angles in Selected Joints During Topspin Forehand in Table Tennis.

The aims of this study were to evaluate movement patterns of topspin forehand, to define the main principles of performing this shot, and to determine the essential differences in individual types of topspin forehand. In total, 10 female high-level athletes participated in this study. The BTS analysis system was used with a novel model for the range-of-motion measurement. An acoustic sensor was attached to the racket for identification of a ball-racket contact. Players, performing topspin forehand, attempt to achieve maximal racket velocity based on the principles of proximal-to-distal sequences and summation of speed with a stretch-shortening character of cycle. The essential differences between type of topspin forehand occurred in the range of motion. Increased power of topspin shot was accompanied by a significant increase in range of motion in most of the studied joints and body segments, in particular in the rotation movement of the upper body, pelvis and shoulders, flexion and rotation in the shoulder and elbow joints, and flexion and rotation in knee joints.

Correlation between isometric shoulder strength and racket velocity during badminton forehand smash movements: study of valid clinical assessment methods.

[Purpose] The purpose of this study was to confirm the correlation between racket velocity during the forehand smash movements with shoulder extensor strength and internal rotator strength in the neutral and abducted positions. [Subjects and Methods] Fourteen collegiate badminton players participated in the study. Measurements were performed shoulder strength, using torque calculated from the upper extremity length and the isometric force, and racket velocity during the forehand smash movements. The shoulder extensor strength and internal rotator strength were measured in the neutral and abducted positions. [Results] The extension torque and internal rotation torque of the shoulder in the neutral position were not significantly correlated with racket velocity. Additionally, correlations between extension torque of the shoulder in the maximum abducted position and racket velocity were insignificant. However, the internal rotation torque of the shoulder in the abducted external rotated position was significantly correlated with racket velocity (r=0.652). [Conclusion] The shoulder internal rotator strength in the abducted external rotated position are suitable measurements for evaluating badminton players.

Development of information-movement couplings in a rhythmical ball-bouncing task: from space- to time-related information.

We studied the development of information-movement couplings in a ball-bouncing task with a special interest in how space- and time-related information is used by people of different ages. Participants from four age groups (children aged 7-8, 9-10 and 11-12 years, and adults) performed a virtual ball-bouncing task in which space- and time-related information were independently manipulated. Task performance and information-movement couplings were analyzed. Our results confirm a clear use of time-related information in adults, while children demonstrated a predominant relationship between space-related information and the period of movement. In the course of development, however, the children become progressively more capable of using time-related information in order to control the rhythmic ball-bouncing task. A second and weaker coupling, between ball height information and racket velocity at impact, also appears in the course of development. The data seem to show that the development of children follows the freezing-freeing-exploiting sequence proposed by Savelsbergh and Van der Kamp (Int J Sport Psychol 31:467-484, 2000), with a significant change in how information is used to control movement related to age.

Mixed control for perception and action: timing and error correction in rhythmic ball-bouncing

The task of bouncing a ball on a racket was adopted as a model system for investigating the behavioral dynamics of rhythmic movement, specifically how perceptual information modulates the dynamics of action. Two experiments, with sixteen participants each, were carried out to definitively answer the following questions: How are passive stability and active stabilization combined to produce stable behavior? What informational quantities are used to actively regulate the two main components of the action-the timing of racket oscillation and the correction of errors in bounce height? We used a virtual ball-bouncing setup to simultaneously perturb gravity (g) and ball launch velocity (v b) at impact. In Experiment 1, we tested the control of racket timing by varying the ball's upward half-period t up while holding its peak height h p constant. Conversely, in Experiment 2, we tested error correction by varying h p while holding t up constant. Participants adopted a mixed control mode in which information in the ball's trajectory is used to actively stabilize behavior on a cycle-by-cycle basis, in order to keep the system within or near the passively stable region. The results reveal how these adjustments are visually controlled: the period of racket oscillation is modulated by the half-period of the ball's upward flight, and the change in racket velocity from the previous impact (via a change in racket amplitude) is governed by the error to the target.

The Effect of Age on Discrete Kinematics of the Elite Female Tennis Serve

The importance of the flat serve in tennis is well documented, with an abundance of research evaluating the service technique of adult male players. Comparatively, the female and junior serves have received far less attention. Therefore, the aims of this study were to quantify the flat serve kinematics in elite prepubescent, pubescent, and postpubescent female tennis players. Full body, racket, and ball kinematics were derived using a 22-camera Vicon motion capture system. Racket velocity was significantly lower in the prepubescent group than in the two older groups. In generating racket velocity, the role of the serving arm appears to become more pronounced after the onset of puberty, whereas leg drive and "shoulder-over-shoulder" rotation mature even later in development. These factors are proposed to relate to strength deficits and junior players' intentions to reduce the complexity of the skill. Temporally, coupling perception (cues from the ball) and action (body movements) are less refined in the prepubescent serve, presumably reducing the "rhythm" (and dynamism) of the service action. Practically, there appears scope for equipment scaling to preserve kinematic relevance between the junior and senior serve and promote skill acquisition.

Recognition of Tennis Serve Performed by a Digital Player: Comparison among Polygon, Shadow, and Stick-Figure Models

The objective of this study was to assess the cognitive effect of human character models on the observer's ability to extract relevant information from computer graphics animation of tennis serve motions. Three digital human models (polygon, shadow, and stick-figure) were used to display the computationally simulated serve motions, which were perturbed at the racket-arm by modulating the speed (slower or faster) of one of the joint rotations (wrist, elbow, or shoulder). Twenty-one experienced tennis players and 21 novices made discrimination responses about the modulated joint and also specified the perceived swing speeds on a visual analogue scale. The result showed that the discrimination accuracies of the experienced players were both above and below chance level depending on the modulated joint whereas those of the novices mostly remained at chance or guessing levels. As far as the experienced players were concerned, the polygon model decreased the discrimination accuracy as compared with the stick-figure model. This suggests that the complicated pictorial information may have a distracting effect on the recognition of the observed action. On the other hand, the perceived swing speed of the perturbed motion relative to the control was lower for the stick-figure model than for the polygon model regardless of the skill level. This result suggests that the simplified visual information can bias the perception of the motion speed toward slower. It was also shown that the increasing the joint rotation speed increased the perceived swing speed, although the resulting racket velocity had little correlation with this speed sensation. Collectively, observer's recognition of the motion pattern and perception of the motion speed can be affected by the pictorial information of the human model as well as by the perturbation processing applied to the observed motion.

Comparison of Endpoint Data Treatment Methods for the Estimation of Kinematics and Kinetics Near Impact During the Tennis Serve

Tennis stroke mechanics have attracted considerable biomechanical analysis, yet current filtering practice may lead to erroneous reporting of data near the impact of racket and ball. This research had three aims: (1) to identify the best method of estimating the displacement and velocity of the racket at impact during the tennis serve, (2) to demonstrate the effect of different methods on upper limb kinematics and kinetics and (3) to report the effect of increased noise on the most appropriate treatment method. The tennis serves of one tennis player, fit with upper limb and racket retro-reflective markers, were captured with a Vicon motion analysis system recording at 500 Hz. The raw racket tip marker displacement and velocity were used as criterion data to compare three different endpoint treatments and two different filters. The 2nd-order polynomial proved to be the least erroneous extrapolation technique and the quintic spline filter was the most appropriate filter. The previously performed "smoothing through impact" method, using a quintic spline filter, underestimated the racket velocity (9.1%) at the time of impact. The polynomial extrapolation method remained effective when noise was added to the marker trajectories.