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The topspin tennis forehand drive has become a feature of modern game; yet, as compared to the serve, there has been little research analysing its kinematics. This is surprising given that there is considerably more variation in the execution of the topspin forehand. Our study is the first to examine the amplitude of upper limb joint rotations that produce topspin in the forehand drives of 14 male competitive tennis players using video-based motion analysis. Humerothoracic abduction ( - )/adduction (+), extension ( - ) /flexion (+), and external ( - )/internal (+) rotation, elbow extension ( - ) /flexion (+) and forearm supination ( - )/pronation (+), wrist extension ( - )/flexion (+) and ulnar ( - )/radial ( - ) deviation were computed. Our findings revealed that the generation of topspin demanded more humeral extension and forearm pronation but less humeral internal rotation angular displacement during the forwardswing. The follow-through phase of the topspin shot was characterised by greater humeral internal rotation and forearm pronation, and reduced humeral horizontal adduction when compared to the flat shot. This study provides practitioners with a better understanding of the upper limb kinematics associated with the topspin tennis forehand drive production to help guide skill acquisition interventions and physical training.

The aim of this study was to examine the respective aptitudes of three rotation sequences (Y t X f 'Y h '', Z t X f 'Y h '', and X t Z f 'Y h '') to effectively describe the orientation of the humerus relative to the thorax during a movement involving a large horizontal abduction/adduction component: the tennis forehand drive. An optoelectronic system was used to record the movements of eight elite male players, each performing ten forehand drives. The occurrences of gimbal lock, phase angle discontinuity and incoherency in the time course of the three angles defining humerothoracic rotation were examined for each rotation sequence. Our results demonstrated that no single sequence effectively describes humerothoracic motion without discontinuities throughout the forehand motion. The humerothoracic joint angles can nevertheless be described without singularities when considering the backswing/forward-swing and the follow-through phases separately. Our findings stress that the sequence choice may have implications for the report and interpretation of 3D joint kinematics during large shoulder range of motion. Consequently, the use of Euler/Cardan angles to represent 3D orientation of the humerothoracic joint in sport tasks requires the evaluation of the rotation sequence regarding singularity occurrence before analysing the kinematic data, especially when the task involves a large shoulder range of motion in the horizontal plane.

The primary role of the shoulder joint in tennis forehand drive is at the expense of the loadings undergone by this joint. Nevertheless, few studies investigated glenohumeral (GH) contact forces during forehand drives. The aim of this study was to investigate GH compressive and shearing forces during the flat and topspin forehand drives in advanced tennis players. 3D kinematics of flat and topspin forehand drives of 11 advanced tennis players were recorded. The Delft Shoulder and Elbow musculoskeletal model was implemented to assess the magnitude and orientation of GH contact forces during the forehand drives. The results showed no differences in magnitude and orientation of GH contact forces between the flat and topspin forehand drives. The estimated maximal GH contact force during the forward swing phase was 3573 ± 1383 N, which was on average 1.25 times greater than during the follow-through phase, and 5.8 times greater than during the backswing phase. Regardless the phase of the forehand drive, GH contact forces pointed towards the anterior-superior part of the glenoid therefore standing for shearing forces. Knowledge of GH contact forces during real sport tasks performed at high velocity may improve the understanding of various sport-specific adaptations and causative factors for shoulder problems.

The purpose of this study was to examine the relationship between the upper limb anthropometric dimensions and a history of dominant upper limb injury in tennis players. Dominant and non-dominant wrist, forearm, elbow and arm circumferences, along with a history of dominant upper limb injuries, were assessed in 147 male and female players, assigned to four groups based on location of injury: wrist (n = 9), elbow (n = 25), shoulder (n = 14) and healthy players (n = 99). From anthropometric dimensions, bilateral differences in circumferences and in proportions were calculated. The wrist group presented a significant bilateral difference in arm circumference, and asymmetrical bilateral proportions between wrist and forearm, as well as between elbow and arm, compared to the healthy group (6.6 ± 3.1% vs. 4.9 ± 4.0%, P < 0.01; -3.6 ± 3.0% vs. -0.9 ± 2.9%, P < 0.05; and -2.2 ± 2.2% vs. 0.1 ± 3.4%, P < 0.05, respectively). The elbow group displayed asymmetrical bilateral proportions between forearm and arm compared to the healthy group (-0.4 ± 4.3% vs. 1.5 ± 4.0%, P < 0.01). The shoulder group showed significant bilateral difference in elbow circumference, and asymmetrical bilateral proportions between forearm and elbow when compared to the healthy group (5.8 ± 4.7% vs. 3.1 ± 4.8%, P < 0.05 and -1.7 ± 4.5% vs. 1.4 ± 4.3%, P < 0.01, respectively). These findings suggest that players with a history of injury at the upper limb joint present altered dominant upper limb proportions in comparison with the non-dominant side, and such asymmetrical proportions would appear to be specific to the location of injury. Further studies are needed to confirm the link between location of tennis injury and asymmetry in upper limb proportions using high-tech measurements in symptomatic tennis players.

This study aimed to investigate the effects of two different racket models and two different forehand drive velocities on the three-dimensional vibration behavior of the racket and shock transmission to the player's wrist under real playing conditions. Nine tennis players performed a series of crosscourt flat forehand drives at two velocities, using a lightly and a highly vibrant racket. Two accelerometers were fixed on the racket frame and the player's wrist. The analysis of vibration signals in both time and frequency domains showed no interaction effect of velocity and racket conditions either on the racket vibration behavior or on shock transmission. An increase in playing velocity enlarged the amount of vibrations at the racket and wrist, but weakly altered their frequency content. As compared to a racket perceived as highly vibrating, a racket perceived as lightly vibrating damped longer in the out-of-plane axis of the racket and shorter on the other axis of the racket and on the wrist, and displayed a lower amount of energy in the high frequency of the vibration signal at the racket and wrist. These findings indicated that the playing velocity must be controlled when investigating the vibration loads due to the racket under real playing conditions. Similarly, a reduced perception of vibration by the tennis player would be linked to decreased amplitude of the racket vibration signal, which may concentrate the signal energy in the low frequencies.

Purpose: This study aimed to describe the scapulothoracic kinematics during the tennis serve in highly skilled tennis players., Methods: Thirteen male competitive players performed flat first serves while eight high-speed cameras recorded the three-dimensional trajectories of the 15 markers located on bony landmarks. The scapular position through the tennis serve was determined using the acromial marker cluster method., Results: The results revealed that, during the cocking phase, the scapula externally rotated and posteriorly tilted to attain the maximal humeral external rotation. During the acceleration phase, the scapula upwardly rotated and anteriorly tilted to reach maximal racket head height. During the follow-through phase, the scapula internally and downwardly rotated, and posteriorly tilted, while the upper limb lowered and crossed the player's body., Conclusions: The findings of this study provide new knowledge on the asymptomatic scapular motion during the tennis serve, which may help clinicians and coaches to understand the overhead sport motion mechanics and to better prevent and rehabilitate overhead shoulder injuries.

This study examined the effect of the polar moment of inertia of a tennis racket on upper limb loading in the serve. Eight amateur competition tennis players performed two sets of 10 serves using two rackets identical in mass, position of center of mass and moments of inertia other than the polar moment of inertia (0.00152 vs 0.00197 kg.m2). An eight-camera motion analysis system collected the 3D trajectories of 16 markers, located on the thorax, upper limbs and racket, from which shoulder, elbow and wrist net joint moments and powers were computed using inverse dynamics. During the cocking phase, increased racket polar moment of inertia was associated with significant increases in the peak shoulder extension and abduction moments, as well the peak elbow extension, valgus and supination moments. During the forward swing phase, peak wrist extension and radial deviation moments significantly increased with polar moment of inertia. During the follow-through phase, the peak shoulder adduction, elbow pronation and wrist external rotation moments displayed a significant inverse relationship with polar moment of inertia. During the forward swing, the magnitudes of negative joint power at the elbow and wrist were significantly larger when players served using the racket with a higher polar moment of inertia. Although a larger polar of inertia allows players to better tolerate off-center impacts, it also appears to place additional loads on the upper extremity when serving and may therefore increase injury risk in tennis players.

Scapular dyskinesis is recognized as an abnormality in the kinetic chain; yet, there has been little research quantifying scapular motion during sport tasks. Tennis forehand drives of eight highly skilled tennis players were studied to assess the scapulothoracic kinematics and evaluate repeatability using video-based motion analysis. Scapulothoracic downward/upward rotation, posterior/anterior tilt, and internal/external rotation were computed using an acromial marker cluster. On average, the upward rotation, anterior tilt, and internal rotation varied from 1 degrees to 26 degrees, from 7 degrees to 32 degrees, and from 42 degrees to 100 degrees, respectively, during the tennis forehand drive. During the backswing and forward swing phases of the forehand stroke, small changes were observed for the three scapular angle values, while all angles increased rapidly during the follow-through phase. This suggests that the tennis forehand drive may contribute to scapula dyskinesis, mainly due to the great amplitude in scapulothoracic anterior tilt and internal rotation observed during the follow-through phase. Knowledge of normal scapula motion during sport tasks performed at high velocity could improve the understanding of various sport-specific adaptations and pathologies.

It is commonly believed that during mental rotation of body parts, participants tend to imagine their own body part moving toward the stimulus, thus using an egocentric strategy. Several studies have also shown that the mental rotation of hands is affected by the actual hand position, especially if the hand is kept in an awkward position. However, this hand posture effect, as well as the use of an egocentric strategy during mental rotation of body parts, is not systematic. Several experiments have demonstrated that manipulating the stimulus features or the paradigm could induce a shift to visual and allocentric strategies. Here, we studied the effects of hand posture and biomechanical constraints on one-hand mental rotation (laterality judgment task), two-hand mental rotation (same-different judgment task), and mental rotation of one or two alphanumeric symbols (control tasks). Effects of posture and biomechanical constraints were observed solely for the laterality judgment task. Response times in the same-different hand mental rotation items were influenced by the angular disparity between the stimuli. We interpreted our result as evidence of the use of different strategies for each task. Future research should focus on disentangling the exact subprocesses in which an egocentric strategy is used, in order to propose better tests for participants with motor impairments.

This study aimed at investigating the influence of three rackets on shoulder net joint moments, power and muscle activity during the flat tennis serve under field- conditions. A 6-camera Eagle(®) motion analysis system, operating at 256 Hz, captured racket and dominant upper limb kinematics of the serve in five tennis players under three racket conditions (A: low mass, high balance and polar moment, B: low three moments of inertia, and C: high mass, swingweight and twistweight). The electromyographic activity of six trunk and arm muscles was simultaneously recorded. Shoulder net joint moments and power were computed by 3D inverse dynamics. The results showed that greater shoulder joint power and internal/external rotation peak moments were found to accelerate and decelerate racket A in comparison with the racket C. Moreover, serving with the racket A resulted in less activity in latissimus dorsi muscle during the acceleration phase, and biceps brachii muscle during the follow-through phase when compared with racket C. These initial findings encourage studying the biomechanical measurements to quantify the loads on the body during play in order to reduce them, and then prevent shoulder injuries. Racket specifications may be a critical point for coaches who train players suffering from shoulder pain and chronic upper limb injuries should be considered in relation to the racket specifications of the players. Key PointsLight racket required more joint power than heavy one to achieve similar post impact ball velocity.Serving with a light racket resulted in higher shoulder internal and external rotation moments than using a heavy one for similar performance.Chronic shoulder pain should encourage coaches to check for potentially inappropriate racket specifications of their players.

The aim of this study was to examine the effects of 2 training modalities on the tennis forehand drive performance. Forty-four tennis players (mean ± SD: age = 26.9 ± 7.5 years; height = 178.6 ± 6.7 cm; mass = 72.5 ± 8.0 kg; International Tennis Number = 3) were randomly assigned into 3 groups. During 6 weeks, the first group performed handled medicine ball (HMB) throws included in the regular tennis practice, the second group (overweight racket-OWR) played tennis forehand drives with an overweighed racket during the regular tennis practice, and the third group (regular tennis training-RTT) practiced only tennis training as usual. Before and after the 6-week program, velocity and accuracy of tennis crosscourt forehand drives were evaluated in the 3 groups. The main results showed that after 6-week training, the maximal ball velocity was significantly increased in HMB and OWR groups in comparison with RTT (p < 0.001 and p = 0. 001, respectively). The estimated averaged increase in ball velocity was greater in HMB than in OWR (11 vs. 5%, respectively; p = 0.017), but shot accuracy tended to be deteriorated in HMB when compared with OWR and RTT (p = 0.043 and p = 0.027, respectively). The findings of this study highlighted the efficiency of both training modalities to improve tennis forehand drive performance but also suggested that the HMB throws may be incorporated into the preseason program preferably, whereas the OWR forehand drives may be included in the on-season program.

This study aimed at investigating the relationship between the trunk and upper limb muscle coordination and mass of the tennis racket during forehand drive. A total of 15 male tennis players performed seven series of ten crosscourt forehand drives, both with their personal racket and six rackets with increased mass ranging from 6 to 16% (step = 2%) of their personal racket mass. The electromyographic (EMG) activity was recorded from nine trunk and upper limb muscles. The onset before impact and EMGrms values of the bursts were individually calculated. Results showed that the ball speed and the muscle activation temporal sequences were similar, whatever the increase in racket mass. Interestingly, in all participants, the activation level of the pectoralis major, latissimus dorsi and biceps brachii decreased when the racket mass increased, while the variations in the anterior deltoid activation level were correlated to the individual personal racket mass. These findings strongly suggest that the study of muscle activity during tennis practice should be considered as a complementary technique to determine a better adequacy of the racket characteristics to those of the player.

A wide range of experimental studies have provided evidence that a night of sleep may enhance motor performance following physical practice (PP), but little is known, however, about its effect after motor imagery (MI). Using an explicitly learned pointing task paradigm, thirty participants were assigned to one of three groups that differed in the training method (PP, MI, and control groups). The physical performance was measured before training (pre-test), as well as before (post-test 1) and after a night of sleep (post-test 2). The time taken to complete the pointing tasks, the number of errors and the kinematic trajectories were the dependent variables. As expected, both the PP and the MI groups improved their performance during the post-test 1. The MI group was further found to enhance motor performance after sleep, hence suggesting that sleep-related effects are effective following mental practice. Such findings highlight the reliability of MI in learning process, which is thought consolidated when associated with sleep.