Ball-racket Impact Research Articles

Lower Limb Biomechanics during the Topspin Forehand in Table Tennis: A Systemic Review.

The aim of this study is to review the valuable lower limb biomechanical contribution to table tennis topspin forehand. Databases included Scopus, PubMed, and Web of science. In this case, 19 articles were selected for the systematic review. The mechanics of the plantar, lower limb joints kinematics and kinetics, muscle activity, and racket-joint relationship are described through gender, performance level, and footwork. The study found that the hip movement characteristics and the hip muscle group activity following a proximal-to-distal sequence strategy significantly contributed to the maximum acceleration of the racket. Optimizing the motion strategy of the ankle and plantar as well as the ankle muscle group activity is beneficial for the transmission of energy in the kinetic chain. Muscle groups around the ankle and subtalar joints are heavily activated during landing to maintain foot stability during the landing phase. Lower limb muscle development plays an important role in movement control and stability as well as sports injury prevention in table tennis footwork during the performance of the topspin forehand. Furthermore, physical development levels and anatomical differences (such as hip and lower trunk muscle strength differences), maybe the main reasons for gender differences observed during the topspin forehand. Systematically summarizing this valuable information can contribute to athletes’ and coaches’ knowledge to enhance topspin forehand performance and training regimes. We suggest that future research could consider the joint contact forces, ball movement, and ball-racket impact during a performance of topspin forehand.

The effect of ball impact location on racket and forearm joint angle changes for one-handed tennis backhand groundstrokes

ABSTRACTRecreational tennis players tend to have higher incidence of tennis elbow, and this has been hypothesised to be related to one-handed backhand technique and off-centre ball impacts on the racket face. This study aimed to investigate for a range of participants the effect of off-longitudinal axis and off-lateral axis ball–racket impact locations on racket and forearm joint angle changes immediately following impact in one-handed tennis backhand groundstrokes. Three-dimensional racket and wrist angular kinematic data were recorded for 14 university tennis players each performing 30 “flat” one-handed backhand groundstrokes. Off-longitudinal axis ball–racket impact locations explained over 70% of the variation in racket rotation about the longitudinal axis and wrist flexion/extension angles during the 30 ms immediately following impact. Off-lateral axis ball–racket impact locations had a less clear cut influence on racket and forearm rotations. Specifically off-longitudinal impacts below the longitudinal axis forced the wrist into flexion for all participants with there being between 11° and 32° of forced wrist flexion for an off-longitudinal axis impact that was 1 ball diameter away from the midline. This study has confirmed that off-longitudinal impacts below the longitudinal axis contribute to forced wrist flexion and eccentric stretch of the wrist extensors and there can be large differences in the amount of forced wrist flexion from individual to individual and between strokes with different impact locations.

The effect of stereotype threat on performance of a rhythmic motor skill.

Many studies using cognitive tasks have found that stereotype threat, or concern about confirming a negative stereotype about one's group, debilitates performance. The few studies that documented similar effects on sensorimotor performance have used only relatively coarse measures to quantify performance. This study tested the effect of stereotype threat on a rhythmic ball bouncing task, where previous analyses of the task dynamics afforded more detailed quantification of the effect of threat on motor control. In this task, novices hit the ball with positive racket acceleration, indicative of unstable performance. With practice, they learn to stabilize error by changing their ball-racket impact from positive to negative acceleration. Results showed that for novices, stereotype threat potentiated hitting the ball with positive racket acceleration, leading to poorer performance of stigmatized females. However, when the threat manipulation was delivered after having acquired some skill, reflected by negative racket acceleration, the stigmatized females performed better. These findings are consistent with the mere effort account that argues that stereotype threat potentiates the most likely response on the given task. The study also demonstrates the value of identifying the control mechanisms through which stereotype threat has its effects on outcome measures.

Subject-specific computer simulation model for determining elbow loading in one-handed tennis backhand groundstrokes

A subject-specific angle-driven computer model of a tennis player, combined with a forward dynamics, equipment-specific computer model of tennis ball–racket impacts, was developed to determine the effect of ball–racket impacts on loading at the elbow for one-handed backhand groundstrokes. Matching subject-specific computer simulations of a typical topspin/slice one-handed backhand groundstroke performed by an elite tennis player were done with root mean square differences between performance and matching simulations of < 0.5°over a 50 ms period starting from ball impact. Simulation results suggest that for similar ball–racket impact conditions, the difference in elbow loading for a topspin and slice one-handed backhand groundstroke is relatively small. In this study, the relatively small differences in elbow loading may be due to comparable angle–time histories at the wrist and elbow joints with the major kinematic differences occurring at the shoulder. Using a subject-specific angle-driven computer model combined with a forward dynamics, equipment-specific computer model of tennis ball–racket impacts allows peak internal loading, net impulse, and shock due to ball–racket impact to be calculated which would not otherwise be possible without impractical invasive techniques. This study provides a basis for further investigation of the factors that may increase elbow loading during tennis strokes.

Investigations into the effect of grip tightness on off-centre forehand strikes in tennis

Previous experimental studies into the dynamics of a ball–racket impact have recorded ball velocities and trajectories in one or two dimensions. These studies were limited in terms of possible impact positions and the ability to represent realistic impact conditions. As the number of dimensions in an experiment increases, it becomes difficult to isolate single variables and to monitor their effect on the output. This paper describes a method of accurately assessing the effect of specific independent variables in impact experiments with a large number of variables. A total of 900 impacts on a Head Ti-S6 tennis racket were recorded within bespoke impact apparatus. The impact velocity, the impact angle, the impact position, and a restrictive torque about the handle were varied between each impact. Each test was recorded with two Phantom high-speed video cameras at 600 frames/s; the use of two cameras allowed the ball trajectory to be tracked in three dimensions. A multi-variate fit based on a second-order polynomial was used to establish trends within the data. It was found that applying a torque about the handle reduced the angular deviation for all impact positions along the racket's transverse axis. In a standard forehand shot, a firm grip reduces the flight time and angle of trajectory of the ball after impact, suggesting that a firm grip is beneficial during competitive play.

Poster Session I, July 14th 2010 — Abstracts The effects of ball impact location on wrist flexion for one-handed tennis backhand groundstrokes

A torque-driven, 3D computer simulation model of an arm-racket system was used to investigate the effects of ball impact location (nine locations on the stringbed) on wrist flexionfor one-handed tennis backhand groundstrokes. The model consists of nine segments with three rotational degrees of freedom at the shoulder, two at the elbow, two at the wrist, three at the grip and two between the racket handle and racket head. Seven pairs of torque generators were used to control joint angle changes with each pair of torque generators representing the torque exerted by the corresponding agonist-antagonist muscles across a joint. The torque exerted during a simulation was determined by multiplying maximum voluntary torque and the corresponding torque activation level which was specified as a function of time using flexor and extensor torque activation profiles. The stringbed was represented by nine point masses connected to each other and the racket frame with elastic springs and three torsional springdampers between the hand and the racket were used to represent grip tightness. The model was designed so that the ball could contact the racket at any of the nine point mass locations and therefore allow simulations for different ball impact locations. The starting point of all simulations was a matched centre impact trial with all parameters in the model kept at the values used in the matching simulation apart from ball impact location. For each perturbation of ball impact location, simulations were run for a 50 ms period starting with ball-racket impact. The effect of ball impact location on the movement of the racket and wrist could be clearly grouped into three impact locations; above the longitudinal axis of the racket, on the longitudinal axis of the racket and below the longitudinal of the racket. Simulations showed that during off-centre impacts below the longitudinal axis of the racket, the wrist was forced to flex up to 16∘ more due to substantial racket rotation within the hand when compared to a matched centre impact simulation. As a consequence off-centre impacts below the longitudinal axis of the racket may be a substantial contributing factor for tennis elbow injuries due to forced wrist flexion and eccentric contraction of the wrist extensors.

Improved tennis ball design: incorporating mechanical and psychological influences

Engineering design decisions for sporting goods are traditionally made with regards to objective performance measures with little regard for perceived product feel and performance. This paper develops a design methodology to relate measurable performance properties to player-perceived performance, feel, and aesthetics. By accounting for player perception in the design process, manufacturers have the opportunity to develop high-performing products that are well received by consumers. Product performance and perception are assessed using tennis balls, a frequently purchased tennis item subject to wear during play. Ball flight and impact performance are evaluated and related to player perceptions of ball performance and sensations trigged during the ball–racket impact. Results suggest tennis ball damping, peak force, and drag coefficient measurements can be used to infer perceptions of ball liveliness, hardness, and flight speed. Aesthetic differences, such as ball fuzziness and logo condition, are proposed to play a more important role in perceptions of ball quality than previously thought.

Effect of ball size on player reaction and racket acceleration during the tennis volley

The purpose of this study was to examine the effect of ball size on reaction time (from ball projection to initial racket movement), movement time (from ball projection to ball-racket impact), mean rectified acceleration and vibration frequency of the racket during the impact phase (100 ms duration after ball-racket impact) of the tennis volley. Twenty-nine beginning to intermediate level tennis players performed volleys under 18 experimental conditions including variations in lateral contact location (forehand and backhand), ball type (Penn oversize, Wilson oversize, regular size), and ball speed (fast, medium, slow). A ball machine was shielded so that the subjects could not predict the ball trajectory before it was released from the machine. Outcome measures were determined using a miniature uni-axial accelerometer and a Photogate timing device. ANOVA with repeated measures and Tukey's post hoc tests were used in statistical analyses (p < .025). The reaction times for the fast speed were significantly shorter than the corresponding times for the slow speed and the reaction times for the forehand volley were significantly shorter than that of the backhand volley. The significant interaction in movement time between ball speed and ball type indicates that the benefits of the larger ball (to slow the game down) increase as the ball speed increases. No significant effect of ball type or ball speed, or interactions were found on mean rectified acceleration and vibration frequency. These results suggest that oversized balls would not cause an increased load to the hitting arm while executing a tennis volley.

T-3-4-3 Dynamics of the Ball-Racket Impact in Tennis : Contact Force, Contact Time, Coefficient of Restitution, and Deformation

T-3-4-3 Dynamics of the Ball-Racket Impact in Tennis : Contact Force, Contact Time, Coefficient of Restitution, and Deformation

Finite Element Anaysis of Impact of a Ball on a Tennis Racket. Optimal Racket Design for the Improvement of Restitution Performance.

For the design of tennis racket, finite element analysis using a realistic model is the most powerful tool. Total analysis system based on finite element method for the ball-racket impact without ball-spin has been developed. Improvement of the standard tennis racket in order to increase its coefficient of restitution is performed by using the developed system. Effects of changes of stiffiness, mass and string pattern for the racket are investigated. It is found that the optimal arrangement of frame mass is effective for the up of restitution performance of racket. Finally, an example of the improved racket is presented and its higher performance is verified. From present analysis, the applicability of the developed system to the optimal racket design is demonstrated.

Application of computer animation techniques for presenting biomechanical research results

Computer animation is becoming a widely accepted method for presenting results of biomechanical analyses and simulations. After summarizing the main aspects of three-dimensional and video overlaid animation, two applications of these techniques are presented. A parameterized graphical model of the tennis racket has been developed, which can be used for visualizing the simulated ball–racket impact phase. In the second example, high-speed video sequences of recorded drop jumps are overlaid with graphical elements to compare methods for determining the jumping height and related parameters. These graphical elements represent quantities, which are calculated applying the different methods. Differences can vividly be demonstrated.

Hyperoxalurie primitive sans anomalie en alanine glyoxylate-aminotransférase (AGT)

Computer animation is becoming a widely accepted method for presenting results of biomechanical analyses and simulations. After summarizing the main aspects of three-dimensional and video overlaid animation, two applications of these techniques are presented. A parameterized graphical model of the tennis racket has been developed, which can be used for visualizing the simulated ball–racket impact phase. In the second example, high-speed video sequences of recorded drop jumps are overlaid with graphical elements to compare methods for determining the jumping height and related parameters. These graphical elements represent quantities, which are calculated applying the different methods. Differences can vividly be demonstrated.

Wrist kinematics differ in expert and novice tennis players performing the backhand stroke: Implications for tennis elbow

Investigators have suggested that the greater prevalence of lateral humeral epicondylitis (tennis elbow, TE) in novice tennis players compared to expert players may reflect the novice players' use of faulty mechanics for the backhand stroke. We investigated the wrist kinematics (flexion/extension), grip pressures, and wrist muscle electromyographic activity in novice ( N = 8) and expert ( N = 8) tennis players performing the backhand stroke. Experts performed the backhand stroke with the wrist extended (re: neutral alignment of the forearm and hand dorsum). Collision of the ball and racket occurred with the wrist extended an average of 0.41 rad (about 23° from neutral alignment) in the expert players; moreover, their wrists were moving further into extension at impact. In contrast, novice subjects struck the ball with the wrist flexed 0.22 rad (about 13°) while moving their wrists further into flexion. Wrist extensor EMGs showed similar levels of activity during the 500 ms interval before ball-racket impact, whereas expert subjects displayed greater EMG levels after contact, consistent with the accompanying wrist extension. The wrist kinematic and EMG data together show that the novice subjects eccentrically contracted their wrist extensor muscles throughout the stroke. We argue that conditions exist for novice subjects that assist stretch of wrist extensor muscles upon collision of the ball and racket. The resulting eccentric contraction of wrist extensor muscles may contribute to lateral TE in novice players, given previous research indicating that eccentric muscle contraction facilitates muscle fiber injury.

Analysis of Coefficient of Restitution during a Nonlinear Impact between a Ball and Strings Considering Vibration Modes of Racket Frame.

The performance of a tennis racket with the coefficient of restitution (COR) is closely related to the impact phenomena. In this paper, the distribution of the coefficient of restitution of a tennis racket when the racket vibrates is predicted using an approximate nonlinear impact model and an experimentally identified vibration model of a tennis racket on the basis of the idea that the COR can be derived from the energy loss during ball-racket impact. The calculated COR, considering the main sources of energy loss such as the impact between the ball and strings, rotation of the racket and vibration of the racket-frame, can explain the experimental results very well.

CAE of Tennis Rackets with Impact Phenomena. The Effect of Strings Tension on a Ball-Racket Impact.

There are a number of unclarified points concerning the impact phenomena and the optimum design of tennis rackets. This paper investigates the effect of string tension on the impact phenomena on the basis of a simple impact model where the contact duration is determined by the natural period of a whole system composed of the mass of the ball, the stiffness of ball and strings, and the reduced mass of racket at the impact point on the racket face considering the strong nonlinearity of the resforing force of the ball and strings. It also deals with the effect of string tension on the structural vibration of the racket frame, which is supposed to reduce the coefficient of restitution of the tennis racket due to the energy loss of the frame vibration. The calculated results explain fairly well the experimental results.

Impact Vibrations of a Racket Handle and the Wrist Joint in Tennis.

The performance of a tennis racket concerning the shock vibrations of the racket handle during impact is one of the important factors for the optimum design of rackets. This paper investigates the mechanism of shock vibrations caused by the impact between a ball and a racket on the basis of the approximate nonlinear impact model and the vibration model of the racket, identified using the experimental modal analysis, and gives physical explanations for the recorded waveform of measured acceleration of the racket handle and the wrist joint when a male tournament player hits flat forehand drives. The results show that the shock vibrations at the racket handle are composed of the reaction force and the vibrations of the racket frame when the ball hits the strings, and also show that there is no reaction force when the ball hits the center of percussion on the racket face. Furthermore, the reaction force due to ball-racket impact and the vibrations at the racket handle are rather small when the ball hits near the center of the racket face with the normal grip position.

The effects of difference in the thickness of racket frame and the string tension on tennis ball-racket impact

The effects of difference in the thickness of racket frame and the string tension on tennis ball-racket impact

Dynamic analysis of the ball-racket impact in the game of tennis

A new approach to the study of the impact phase in tennis is presented. It allows, in particular, an analysis of the forces transmitted to the arm joints from the racket and calculation of the speed variation of ball and racket subsequent to their impact.

System approach to biomechanics of paretic gait controlled by subcutaneous electrical stimulation

The purpose of this study was to examine the effect of ball size on reaction time (from ball projection to initial racket movement), movement time (from ball projection to ball-racket impact), mean rectified acceleration and vibration frequency of the racket during the impact phase (100 ms duration after ball-racket impact) of the tennis volley. Twenty-nine beginning to intermediate level tennis players performed volleys under 18 experimental conditions including variations in lateral contact location (forehand and backhand), ball type (Penn oversize, Wilson oversize, regular size), and ball speed (fast, medium, slow). A ball machine was shielded so that the subjects could not predict the ball trajectory before it was released from the machine. Outcome measures were determined using a miniature uni-axial accelerometer and a Photogate timing device. ANOVA with repeated measures and Tukey's post hoc tests were used in statistical analysises (p<.025). The reaction times for the fast speed were significantly shorter than the corresponding times for the slow speed and the reaction times for the forehand volley were significantly shorter than that of the backhand volley. The significant interaction in movement time between ball speed and ball type indicates that the benefits of the larger ball (to slow the game down) increase as the ball speed increases. No significant effect of ball type or ball speed, or interactions were found on mean rectified acceleration and vibration frequency. These results suggest that oversized balls would not cause an increased load to the hitting arm while executing a tennis volley.

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