Tennis

Adjustment of segmental rotations to achieve both racket speed and accuracy at various impact heights during a two-handed backhand stroke

This study investigated the influence of impact height and competitive level on racket speed and stroke accuracy by analysing segmental angular kinematics under a random ball condition. High- (HQ, n = 7) and low-quality (LQ, n = 7) groups were determined by k-means clustering of the ratio of ball landing in the target (accuracy) and racket speed decrease. HQ showed higher accuracy (48.3% vs. 32.4%), less speed decrease at lower impact heights (-4.4% vs. -10.3%) and better competitive level ranking [median (1st-3rd quartiles); 4 (2-7)] than LQ [10 (8-13)]. HQ produced greater racket speed (24.4 vs. 21.6 m/s), especially with a notable horizontal velocity (23.8 vs. 20.8 m/s) of the racket at lower impact height, which was attributed to the central role of greater angular velocity of pelvis and thorax in the hitting direction. Both groups showed similar adjustment mechanisms that due to the decrease in angular velocity of pelvis, players increased the relative rotation angle between pelvis and thorax to maintain angular velocity of thorax when transitioning from low to high impact heights. Our findings suggest that players should emphasise the coordination between pelvic and thoracic rotations according to impact heights to maintain racket speed while controlling ball landing position.

Grip position affects upper limb kinematic chain during tennis double-handed backhand topspin strokes: considerations for transitioning tennis grip position technique

The purpose of this study was to compare the upper limb kinematic chain of tennis players using either an eastern or continental non-dominant grip position during the forward swing of the double-handed backhand stroke. Sixteen right-handed tennis players performed backhands using two non-dominant grip positions (eastern and continental), aiming for two cross-court zones (deep and short). Trajectory data were captured using sixty reflective markers attached to the upper limb and racket using a 12-camera Vicon motion capture system (250 Hz). Peak angular velocity was significantly greater for multiple joint rotations at the dominant shoulder and entire non-dominant limb in the eastern grip. Subsequently, greater peak racket head angular velocity and post-impact ball speed were generated by the eastern grip, while shot accuracy was similar between grip types. There was delayed dominant shoulder peak adduction angular velocity for the continental grip, possibly due to a lack of skill familiarity causing changes in coordinative patterns. Collectively, the non-dominant grip position appears to influence proximal and distal upper limb movement. Future research should explore upper limb segment coordination comparing preferred and non-preferred double-handed backhand techniques and complete inter-disciplinary investigations to understand what grip positions are most effective for individuals to learn double-handed backhands.

Validating an algorithm from a trunk-mounted wearable sensor for detecting stroke events in tennis

This study analysed the accuracy of a prototype algorithm for tennis stroke detection from wearable technology. Strokes from junior-elite tennis players over 10 matches were analysed. Players wore a GPS unit containing an accelerometer, gyroscope and magnetometer. Manufacturer-developed algorithms determined stoke type and count (forehands, backhands, serves and other). Matches were video recorded to manually code ball contacts and shadow swing events for forehands, backhands and serves and further by stroke classifications (i.e., drive, volley, slice, end-range). Comparisons between algorithm and coding were analysed via ANOVA and Bland-Altman plots at the match-level and error rates for specific stroke-types. No significant differences existed for stroke count between the algorithm and manual coding (p > 0.05). Significant (p < 0.0001) overestimation of "Other" strokes were observed from the algorithm, with no difference in groundstrokes and serves (p > 0.05). Serves had the highest accuracy of all stroke types (≥98%). Forehand and backhand "drives" were the most accurate (>86%), with volleys mostly undetected (58-60%) and slices and end-range strokes likely misclassified (49-51%). The prototype algorithm accurately quantifies serves and forehand and backhand "drives" and serves. However, underestimations of shadow swings and overestimations of "other" strokes suggests strokes with reduced trunk rotation have poorer detection accuracy.

Acute effects of in-step and wrist weights on change of direction speed, accuracy and stroke velocity in junior tennis players

The main aim of this study was to investigate the acute effects of the use of a weighting set (Powerinstep®) on measures of stroke velocity (StV), accuracy and change of direction speed (CODS) in junior tennis players. A within-subjects design was used to evaluate seventeen (6 female and 11 male) tennis players (mean ± SD; 16.5 ± 1.3 years old; 1.75 ± 8.4 m; 67.0 ± 8.1 kg; 22.04 ± 1.8 kg/m2) on StV of three specific tennis actions (serve, forehand and backhand) and CODS for the following conditions: wearing a 50, 100, 150, 200 g weight or no weight at all (baseline). No significant differences were found between conditions for forehand (F = 0.412; p = 0.799), backhand (F = 0.269; p = 0.897) and serve (F = 0.541; p = 0.706) velocity and forehand (F = 1.688; p = 0.161), backhand (F = 0.567; p = 0.687) and serve (F = 2.382; p = 0.059) accuracy and CODS (F = 0.416; p = 0.797). Small-to-moderate effect sizes (ES) negatively affecting StV when using 200 g compared to the baseline (ES = 0.48, 0.35 and 0.45) could be observed. Moderate (ES = -0.49) and trivial (ES = -0.14 and -0.16) ES for a higher accuracy score were noticed in serve, forehand and backhand 100 g compared to the baseline. Moreover, small ES (ES = 0.41) for improvement in 200 g CODS comparing to baseline conditions were found. These results indicate that the use of a weighting set does not significantly affect StV or CODS respectively. Notwithstanding, small-to-moderate changes show impact in accuracy and no variance in velocity production when using 100 g alongside faster execution in CODS when using 200 g.

A kinematic analysis of the upper limb during the topspin double-handed backhand stroke in tennis

The purpose of this study was to compare double-handed backhand kinematics of the non-dominant wrist of tennis players using either an eastern or continental grip position with the non-dominant hand. Trajectory data were captured using sixty reflective markers on sixteen sub-elite right-handed tennis players using a 12-camera VICON motion capture system (250 Hz). Participants executed double-handed backhands using two non-dominant grip positions (Eastern [E] and Continental [C]), aiming for two crosscourt zones (Deep [D] and Short [S]), totalling to four conditions (ED, CD, ES and CS). Three successful attempts from each condition were selected for analysis. The eastern grip demonstrated faster horizontal racket head velocity compared to the continental grip. However, no differences were observed in accuracy or spin rate between grips (p > 0.05). In the non-dominant upper limb, elbow flexion was smaller in the continental condition throughout the swing, whilst wrist extension and ulnar deviation was larger. Collectively, these data suggest that the continental grip may place the wrist in a position vulnerable to overuse injury. Future research into the kinetics of the double-handed backhand would help better understand the onset of ulnar-side wrist pain in tennis.

Wrist Injuries in Tennis Players: A Narrative Review

The wrist/hand complex forms the crucial final link in the kinetic chain between the body and the racquet and therefore has a number of important roles in the production of all tennis strokes. However, the internal and external loads that are created at the wrist during these strokes have the potential to contribute to pain and injury. Therefore, the purposes of this narrative review are to (1) determine the extent of the problem of wrist pain/injury in tennis players, (2) identify bony and soft tissue structures of the wrist that are susceptible to damage as a result of tennis play and (3) explore factors that may influence the development of wrist pain/injury in tennis players. The epidemiological data revealed two important points. First, some evidence suggests wrist pain/injury accounts for a higher percentage of total injuries in more recent studies (2014-2015) than in early studies (1986-1995). Second, the relative frequency of wrist pain/injury compared with other well-recognized problem areas for tennis players such as the shoulder complex, elbow and lumbar spine is noticeably higher in more recent studies (2014-2015) than in early studies (1986-1995), particularly among females. Collectively, this would seem to indicate that the problem of wrist pain/injury has increased in the modern game. In fact, some wrist injuries appear to be related to the use of certain forehand grip types and the predominant use of the two-handed backhand. While the loads experienced at the wrist during tennis stroke production seem to be below threshold levels for a single event, the cumulative effects of these loads through repetition would appear to be an important consideration, especially when inadequate time is allowed to complete normal processes of repair and adaptation. This is supported by the evidence that most wrist injuries in tennis are associated with overuse and a chronic time course. The complex interaction between load, repetition, and training practices in tennis, particularly among young developing players who choose a path of early specialization, needs to be further explored.

Influence of striking technique on maximum striking velocities-experimental and statistical investigation

Forensic experts often have to assess injury and fatality risks in the context of violent blunt force trauma. Maximum striking velocities in one- and two-handed strikes with a rod-like implement can be of particular interest. Current literature lacks studies addressing this problem. The purpose of this study was therefore to measure and analyse maximum striking velocities in one-handed and two-handed strikes in female and male volunteers. We hypothesised higher striking velocities in two-handed strikes compared to one-handed strikes. Fifty volunteers performed one- and two-handed strikes from top to bottom using a steel rod of 65 cm length and 1000 g weight. A Qualisys™ Motion Analysis system registered displacements of reflecting markers fixed to the rod as well as to the volunteer's body. In one-handed strikes, the mean maximum striking velocity was 17.2 m/s in the female sample and 23.9 m/s in the male sample. Statistically not significantly different maximum striking velocities were found in two-handed strikes with mean values of 18.3 m/s in the female sample and 24.2 m/s in the male sample. Female and male volunteers also yielded similar mean maximum striking velocities in two-handed strikes comparing 'overhead' and 'overshoulder' striking techniques. In conclusion, the striking technique did not relevantly influence maximum striking velocities in our setup.

The kinematics of trunk and upper extremities in one-handed and two-handed backhand stroke

The aim of this study was to present kinematics of trunk and upper extremities in tennis players who perform one-handed and two-handed backhand strokes. The study aimed to address the question of whether one of those techniques has some important advantage over the other. If so, what makes it superior? The study included 10 tennis coaches with average coaching experience of 9 years. The coaches were asked to hit 15 one-handed and two-handed backhands. The tests were carried out in a laboratory. A sponge ball was used in order to protect the measurement equipment. Video motion analysis was carried out using BTS SMART system; images were recorded with 6 cameras with a rate of 120 frames per second. The analysis of both backhand strokes focused on the second phase of the stroke (acceleration). The use of an eight-element model of human body for description of upper body motion in both techniques revealed kinematic differences in how both backhands are performed. The two-handed backhand was performed in closed kinetic chain with 8 degrees of freedom, whereas the one-handed backhand involved an open kinetic chain with 7 degrees of freedom. Higher rigidity of upper extremities which are connected with trunk in the two-handed backhand, contributes to an elevated trunk effect in this stroke. This is confirmed by higher component velocities for racket handle, which result from trunk rotation in the two-handed backhand and a negative separation angle in the two-handed backhand at the moment of contact of the racket with the ball. The study does not provide a clear-cut answer to the question of advantages of one technique over the other; however, it reveals dissimilar patterns of driving the racket in both techniques, which suggests the need for extending the analysis of techniques of both backhands with additional kinematics of tennis racket in consideration of measurements of ball velocities.

Strength and conditioning in tennis: Current research and practice

Virtually all professional tennis players are in continuous pursuit of enhanced performance. With the modern game becoming increasingly dynamic and tournament schedules no less demanding, the importance of physical fitness is well accepted. Indeed, most professional tennis players resource strength and conditioning specialists on a full- or part-time basis. As tennis play is characterised by intricate bio-energetics, planning specific strength and conditioning interventions represents a significant challenge for the specialist. Further, where game physiology and mechanics have been described extensively, critiques of the efficacy of different training initiatives are far less common. This review therefore considers the current scientific, tennis-specific fitness training evidence base in light of contemporary conditioning, and more particularly resistance training, practices.

Anthropometric characteristics, body composition and somatotype of elite junior tennis players

OBJECTIVES

The aims of this study were to describe the anthropometric characteristics, body composition and somatotype of elite male and female junior tennis players, to compare the anthropometric data, body composition and somatotype of the first 12 elite junior tennis players on the ranking with the lower ranked players, and to establish an anthropometric profile chart for elite junior tennis players.

METHODS

A total of 123 (57 males and 66 females) elite junior tennis players participated in this study. The athletes were divided into two groups, the first 12 and the lower ranked players, according to gender. A total of 17 anthropometric variables were recorded of each subject.

RESULTS

There were no significant differences in height and weight between the first 12 and the lower ranked boys, while the first 12 girls were significantly taller than the lower ranked girls (p = 0.009). Significant differences were found for humeral and femoral breadths between the first 12 and the lower ranked girls (p = 0.000; p = 0.004, respectively). The mean (SD) somatotype of elite male junior tennis players could be defined as ectomesomorphic (2.4 (0.7), 5.2 (0.8), 2.9 (0.7)) and the mean (SD) somatotype of elite female junior tennis players evaluated could be defined as endomesomorphic (3.8 (0.9), 4.6 (1.0), 2.4 (1.0)). No significant differences were found in somatotype components between the first 12 and the lower ranked players of both genders.

CONCLUSIONS

When comparing the first 12 and the lower ranked elite junior tennis players of both genders, no significant differences were observed in any measured item for the boys. By contrast, significant differences were observed in height and humeral and femoral breadths between the first 12 and the lower ranked girls, whereby the first 12 were taller and had wider humeral and femoral breadths than the lower ranked players. These differences could influence the playing style of junior female players.

Biomechanics and tennis

Success in tennis requires a mix of player talent, good coaching, appropriate equipment, and an understanding of those aspects of sport science pertinent to the game. This paper outlines the role that biomechanics plays in player development from sport science and sport medicine perspectives. Biomechanics is a key area in player development because all strokes have a fundamental mechanical structure and sports injuries primarily have a mechanical cause.

Comparison of shock transmission and forearm electromyography between experienced and recreational tennis players during backhand strokes

OBJECTIVE

To test the hypothesis that recreational tennis players transmit more shock impact from the racket to the elbow joint than experienced tennis players during the backhand stroke. Also, to test whether recreational tennis players used higher electromyographic (EMG) activities in common wrist extensor and flexor around epicondylar region at follow-through phase.

DESIGN

A repeated-measure, cross-sectional study.

SETTING

National College of Physical Education and Sports at Taipei, Taiwan.

PARTICIPANTS

Twenty-four male tennis players with no abnormal forearm musculoskeletal injury participated in the study. According to performance level, subjects were categorized into 2 groups: experienced and recreational.

MAIN OUTCOME MEASUREMENTS

Impact transmission and wrist extensor-flexor EMG for backhand acceleration, impact, and follow-through phases were recorded for each player. An independent t test with a significance level of 0.05 was used to examine mean differences of shock impact and EMG between the 2 test groups. One-way ANOVA associated with Tukey multiple comparisons was used to identify differences among different impact locations and EMG phases.

RESULTS

Experienced athletes reduced the racket impact to the elbow joint by 89.2%, but recreational players reduced it by only 61.8%. The largest EMG differences were found in the follow-through phase (P<0.05). Experienced athletes showed that their extensor and flexor EMGs were at submaximal level for follow-through phase, whereas recreational players maintained their flexor and extensor EMGs at either supramaximal or maximal level.

CONCLUSIONS

Our results support the hypothesis that recreational players transmit more shock impact from the racket to the elbow joint and use larger wrist flexor and extensor EMG activities at follow-through phase of the backhand stroke. Follow-through control is proposed as a critical factor for reduction of shock transmission. Clinicians or trainers should instruct beginners to quickly release their grip tightness after ball-to-racket impact to reduce shock impact transmission to the wrist and elbow.

Kinematics and kinetics of the racket-arm during the soft-tennis smash under match conditions

The purposes of this study were to (a) describe the racket-arm kinematics and kinetics of the soft-tennis smash during match rallies, and (b) assess the characteristics of this smash vs. the laboratory-simulated smash of our previous study. In the current study we recorded soft-tennis smash motions during match play of the 3rd East Asian Games. Racket-arm anatomical joint angular velocity and anatomical joint torque were calculated from 3-D coordinate data of 13 collected motions obtained using the direct linear transformation procedure. The results showed that most of the maximum values of the anatomical joint torques were qualitatively smaller than those of the tennis serve. Peak elbow extension, shoulder internal rotation, and elbow varus torques in match play were significantly greater than values reported for laboratory-simulated conditions. The greater forward swing torques did not result in significantly different racket head velocity, possibly because there was a significantly shorter forward swing phase in match conditions. In particular, a clear peak of the elbow extension torque during the forward swing phase was the most characteristic pattern in the smashes under match conditions, for it was 160% greater than laboratory-simulated conditions. These results supported our hypothesis that racket-arm kinematic and kinetic characteristics of the smash under match conditions differ from those under laboratory-simulated conditions. Possible explanations include the time-pressure conditions of the competitive situation in a match, and the Hawthorne effect (Hudson et al., 1986), both of which alter performance between match conditions and laboratory-simulated conditions.

Trunk rotation torques through the hip joints during the one- and two-handed backhand tennis strokes

The aim of the present study was to compare kinetically the roles of the lower extremities in generating trunk rotation in the tennis one-handed and two-handed backhand strokes. Fourteen male collegiate tennis players, seven with a preference for the one- and seven with a preference for the two-handed technique, were recruited as participants. The motion of each backhand stroke was filmed using two high-speed cine-cameras, and the ground reaction forces on the feet were measured separately using two force platforms to determine the joint moments and joint reaction forces at the hip, knee and ankle joints. A significant difference in hip joint moments between the two types of stroke was found in the phase from the start of forward rotation of the pelvis to the start of racket forward movement. For trunk rotation, the one-handed backhand players exerted a large joint moment in the front leg, whereas the two-handed backhand players exerted a large joint moment in the back leg. The exertion of a large hip joint moment in the latter stroke was comparable with the exertion in a forehand stroke reported previously.

An isokinetic profile of trunk rotation strength in elite tennis players

PURPOSE

The changes in stroke production in the modern game of tennis have increased the demands on trunk rotation in elite tennis players. Unlike the shoulder, where unilateral strength adaptations have been identified, no study to date has objectively quantified side to side rotational trunk strength in elite tennis players.

METHODS

One hundred nine elite tennis players were tested using a Cybex isokinetic torso rotation unit at 60 and 120 degrees x s(-1) to measure left and right rotation while stabilized in a seated position. A repeated-measures ANOVA was used with post hoc dependent t-tests where main effect differences were identified to determine side to side rotational differences.

RESULTS

No significant difference in trunk rotation strength was measured in the elite male players. Peak torque to body weight ratios averaged 63.7 and 57.5% for forehand rotation (left rotation in right-handed player) and 64.4 and 59.2% for backhand rotation at 60 and 120 degrees x s(-1), respectively. In females, slightly greater (P < 0.001) backhand rotation strength (right rotation in a right-handed player) was measured at both testing speeds with peak torque to body weight ratios ranging between 47.7 and 45.1% for left rotation and 50.8 and 48.3% for right rotation at 60 and 120 degrees x s(-1), respectively. Left rotation/right rotation ratios ranged from 95 to 98% for males and from 94 to 96% for females.

CONCLUSIONS

Elite-level male tennis players have symmetric trunk rotation strength. Elite female tennis players have slightly greater backhand rotation strength (by 4-8%) than forehand rotation. Conditioning programs for elite tennis players should include exercises to facilitate and develop bilateral trunk rotation.