Biomechanics of the serve in tennis. A biomedical perspective

Prediction of Service Performance Based on Physical Strength in Elite Junior Tennis Players

In tennis, service requires a variety of complicated movements. Given the importance of taking the initiative to obtain points in a tennis match, it is crucial to make full use of speed and spin rate of service. Generally, a service that requires a higher spin rate would slow down, and a service that has increased speed would have a decreased spin rate. For players who are disadvantaged in height, although controlling spin rate is essential, slowing down service speed should be avoided. For these players, the challenge of service is to improve the speed without decreasing the spin rate. Players must also be trained to build physical strength required for this skill. It is not uncommon to work on physical training without a racket; however, few studies have reported on the effects of cultivated physical strength on on-court tennis performance. Therefore, this study aimed to propose physical measurements that could be used as indices to improve service performance in 58 elite Japanese junior male players. To test service performance, we used TrackMan tennis radar device to assess speed, spin rate, impact height, and impact depth. To test physical strength, we measured 5- and 20-m sprint, broad jump, medicine ball throw (forward, backward). We used a significant multiple regression equation to predict the first service speed obtained from the broad jump and the Medicine ball throw (backward). Additionally, a strong correlation was obtained between the predicted and measured values. In addition to physical strength, we suggest that the depth of the impact point (taking the hitting point forward toward the net) is important for improving the first service speed. However, we were not able to identify the physical strength test items that improve service spin rate. Other item should be examined in the future to determine the physical strength associated with spin rate. This result could help connect physical training and service performance.

Fitness testing in tennis: Influence of anthropometric characteristics, physical performance, and functional test on serve velocity in professional players

The aims of this study were to examine the relationship between anthropometric variables, physical performance, and functional test with serve velocity regarding tennis players’ level and to design regression models that effectively predict serve velocity. A sample of sixteen male tennis players participated in this study (national level = 8, professional level = 7). Anthropometric measurements (body mass, height, body mass index and body segments) and physical test (hand strength, countermovement jump, jump on serve, and serve velocity) and functional test (medicine ball throw overhead and shot put) were performed. No differences in anthropometrics and physical test were found between national and professional levels. A significant positive correlation (p < 0.05, ranging for 0.603 to 0.932) was found between some anthropometrics measurements (body mass, height, arm, forearm, and leg segments), physical parameters (hand strength, countermovement jump) and functional test (medicine ball throw shot put and overhead) with serve velocity for all tennis players. Multiple regression analysis indicated that medicine ball throw shot put was the most important test to explain serve velocity (r² = 0.869). The results showed how the combination of physical and anthropometric factors have an impact on serve velocity. In addition, a new functional fitness test (medicine ball throw shot put) is proposed as an alternative to traditional medicine ball throw overhead due to its high reproducibility (inter-trial reliability) and predictive validity values, as well as by multi-segmental coordination movement similar to tennis serve.

Epidemiology and pain in elementary school-aged players: a survey of Japanese badminton players participating in the national tournament

Pain is common in athletes which should be well managed. To identify risk factors for shoulder pain, and the association between shoulder pain, lower back pain and knee pain among elementary school-aged badminton players, we conducted a cross-sectional study to collect data of the past year among 611 elementary school age (7-12 years old) badminton players belonging to the Japan Schoolchildren Badminton Federation using a questionnaire. Odds ratio (OR) and 95% confidence interval (CI) were estimated by multivariate logistic regression analysis. The overall incidence rate of shoulder injuries, lower back injuries and knee injuries was 0.38 injuries per 1000 h of badminton training. Players with training time per day > 2.5 h were 2.64 times (95% CI 1.03-6.78, p = 0.043) more likely to sustain shoulder pain than those with training time per day ≤ 2.5 h. A significant association was revealed between shoulder pain and knee pain as well as between lower back pain and knee pain as training hours per day > 2.5 h. Moreover, lower back pain was significantly associated with shoulder pain independent of training hours per day (≤ 2.5 h: p = 0.001; > 2.5 h: p < 0.001). These findings indicate that training time per day is risk factor, and shoulder pain, lower back pain and knee pain were associated with each other in elementary school-aged badminton players.

Impact of Physical Performance and Anthropometric Characteristics on Serve Velocity in Elite Junior Tennis Players

Fett, J, Ulbricht, A, and Ferrauti, A. Impact of physical performance and anthropometric characteristics on serve velocity in elite junior tennis players. J Strength Cond Res 34(1): 192-202, 2020-This study aimed to investigate the impact of physical performance components and anthropometric characteristics on serve velocity (SV) in elite junior tennis players depending on the sex and age group. A sample of the best 1,019 (male = 625, female = 394) junior squad tennis players of the German Tennis Federation participated in the study involving complex anthropometric measurements (body height, body mass, sitting height, and arm span) and physical tests (e.g., SV, medicine ball throws [MBTs], hand grip strength, push-ups, back extension, countermovement jumps [CMJs], horizontal jumps, 20-m sprint, and tennis-specific endurance). Of all the anthropometric and physical characteristics analyzed, the MBTs (r = 0.49-0.60♂; r = 0.20-0.60♀), hand grip strength (r = 0.43-0.59♂; r = 0.27-0.37♀), arm span (r = 0.37-0.56♂; r = 0.24-0.36♀), body height (r = 0.31-0.52♂; r = 0.26-0.38♀), and body mass (r = 0.44-0.57♂; r = 0.35-0.39♀) were particularly closely correlated with SV. The results of the multiple regression analysis indicated that the combination of selected predictors (e.g., MBTs, grip strength, arm span, and body mass) explained 41-66% of the variance in SV of boys and 19-45%, respectively, for girls. The results reinforce that service speed is dependent on physical abilities and anthropometric characteristics but also strongly on additional factors (i.e., technical components). In particular, the upper-body power/strength is important to the junior players' service, especially in athletes with a greater body height and arm span (i.e., biomechanical advantages), whereas purely lower-body power (e.g., CMJ) is less important. To this effect, talent identification and intervention programs focusing on the specific requirements are recommended.

The Effect of an Arthroscopic Orthopaedic Procedure on a Professional Tennis Player's Career

Orthopaedic injuries can significantly impact the careers of professional tennis players. It is currently unknown how professional tennis players fare after arthroscopic surgery. For the purpose of this study, players ranked in the Association of Tennis Professionals (ATP) and Women’s Tennis Association (WTA) who underwent arthroscopic surgery of any joint between 1996 and 2016 were identified through a well-established, previously published protocol of injury reports and public archives. Performance statistics both before and after surgery, time to return (TTR) to play, and career length following surgery were collected for each player. Statistical analysis was performed with significance accepted at a probability value (p) of <0.05. A total of 55 (39 males and 16 females) players met the inclusion criteria (shoulder, n = 15; elbow, n = 15; wrist, n = 13; hip, n = 12). The average age of the players at the time of surgery was 25.8 (±4) years, and the average career length before surgery was 8.4 (±4) years. Tennis players who underwent arthroscopic shoulder surgery experienced a longer TTR to play (279 days, p <0.01), as well as a greater decline in their rankings, both in the first and second years postoperatively (p <0.01 and p = 0.01, respectively), compared to all other surgical cohorts. Players who underwent surgery on the elbow, wrist, and hip had no significant decline in the ranking by the second postoperative year. There were no significant differences between genders. This study represents the largest database of professional tennis players who have undergone arthroscopic surgery and may allow physicians to provide evidence-based recommendations about expectations after surgical treatment.

Increasing Ball Velocity in the Overhead Athlete: A Meta-analysis of Randomized Controlled Trials

Overhead athletes routinely search for ways to improve sport performance, and one component of performance is ball velocity. The purpose of this meta-analysis was to investigate the effect of different strengthening interventions on ball and serve velocity. A comprehensive literature search with pre-set inclusion and exclusion criteria from 1970 to 2014 was conducted. Eligible studies were randomized control trials including the mean and SDs of both pretest and posttest ball velocities in both the experimental and the control groups. The outcome of interest was ball/serve velocity in baseball, tennis, or softball athletes. Level 2 evidence or higher was investigated to determine the effect different training interventions had on velocity. Pretest and posttest data were extracted to calculate Hedges's g effect sizes with 95% confidence intervals (CIs). Methodological qualities of the final 13 articles within the analysis were assessed using the Physiotherapy Evidence Database scale. The majority of the articles included in this analysis had an effect on velocity with the strongest effect sizes found in periodized training (Hedges's g = 3.445; 95% CI = 1.976-4.914). Six studies had CI that crossed zero, indicating that those specific interventions should be interpreted with caution. Consistent and high-quality evidence exists that specific resistance training interventions have an effect on velocity. These findings suggest that interventions consisting of isokinetic training, multimodal training, and periodization training are clinically beneficial at increasing velocity in the overhead athlete over different windows of time.

Energy flow analysis during the tennis serve: comparison between injured and noninjured tennis players

BACKGROUND

Energy flow has been hypothesized to be one of the most critical biomechanical concepts related to tennis performance and overuse injuries. However, the relationships among energy flow during the tennis serve, ball velocity, and overuse injuries have not been assessed.

PURPOSE

To investigate the relationships among the quality and magnitude of energy flow, the ball velocity, and the peaks of upper limb joint kinetics and to compare the energy flow during the serve between injured and noninjured tennis players.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The serves of expert tennis players were recorded with an optoelectronic motion capture system. The forces and torques of the upper limb joints were calculated from the motion captures by use of inverse dynamics. The amount of mechanical energy generated, absorbed, and transferred was determined by use of a joint power analysis. Then the players were followed during 2 seasons to identify upper limb overuse injuries with a questionnaire. Finally, players were classified into 2 groups according to the questionnaire results: injured or noninjured.

RESULTS

Ball velocity increased and upper limb joint kinetics decreased with the quality of energy flow from the trunk to the hand + racket segment. Injured players showed a lower quality of energy flow through the upper limb kinetic chain, a lower ball velocity, and higher rates of energy absorbed by the shoulder and elbow compared with noninjured players.

CONCLUSION

The findings of this study imply that improper energy flow during the tennis serve can decrease ball velocity, increase upper limb joint kinetics, and thus increase overuse injuries of the upper limb joints.

Effects of the racket polar moment of inertia on dominant upper limb joint moments during tennis serve

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.

Effects of body mass index and full body kinematics on tennis serve speed

Effective training to improve serve speed is important for competitive tennis players. The purposes of this study were to investigate the effects of anthropometric factors and whole body kinematics of elite players on ball speed and to propose possible training strategies for improving the quality of tennis serves. Body and racket kinematics of tennis serves of 12 male elite Hong Kong players were investigated. The tennis serve was divided into four phases: I) Back-Swing Phase, II) Lead-Leg-Drive Phase, III) Forward-Swing Phase, and IV) Follow-Through Phase. It was shown that racket-side knee range of motion during phases II and III (r=0.705; p<0.05), racket-side knee peak extension velocity during phase II (r=0.751; p<0.01), racket-side hip peak extension velocity during phase II (r=0.657; p<0.05), racket-side shoulder range of motion in the coronal plane during phase III (r=0.616; p<0.05), racket-side elbow peak extension velocity during phase III (r=0.708; p<0.01) and body mass index (r=0.577; p<0.05) were significantly correlated with ball speed. Body mass index and the identified kinematic parameters that were significantly correlated with ball speed could be used as training guidelines for coaches and players to improve serve speed. Players should pay particular attention in training to increasing the extension velocity and range of motion of the identified joints.

An 8-stage model for evaluating the tennis serve: implications for performance enhancement and injury prevention

BACKGROUND

The tennis serve is a complex stroke characterized by a series of segmental rotations involving the entire kinetic chain. Many overhead athletes use a basic 6-stage throwing model; however, the tennis serve does provide some differences.

EVIDENCE ACQUISITION

To support the present 8-stage descriptive model, data were gathered from PubMed and SPORTDiscus databases using keywords tennis and serve for publications between 1980 and 2010.

RESULTS

An 8-stage model of analysis for the tennis serve that includes 3 distinct phases-preparation, acceleration, and follow-through-provides a more tennis-specific analysis than that previously presented in the clinical tennis literature. When a serve is evaluated, the total body perspective is just as important as the individual segments alone.

CONCLUSION

The 8-stage model provides a more in-depth analysis that should be utilized in all tennis players to help better understand areas of weakness, potential areas of injury, as well as components that can be improved for greater performance.

Lower trunk kinematics and muscle activity during different types of tennis serves

BACKGROUND

To better understand the underlying mechanisms involved in trunk motion during a tennis serve, this study aimed to examine the (1) relative motion of the middle and lower trunk and (2) lower trunk muscle activity during three different types of tennis serves - flat, topspin, and slice.

METHODS

Tennis serves performed by 11 advanced (AV) and 8 advanced intermediate (AI) male tennis players were videorecorded with markers placed on the back of the subject used to estimate the anatomical joint (AJ) angles between the middle and lower trunk for four trunk motions (extension, left lateral flexion, and left and right twisting). Surface electromyographic (EMG) techniques were used to monitor the left and right rectus abdominis (LRA and RRA), external oblique (LEO and REO), internal oblique (LIO and RIO), and erector spinae (LES and RES). The maximal AJ angles for different trunk motions during a serve and the average EMG levels for different muscles during different phases (ascending and descending windup, acceleration, and follow-through) of a tennis serve were evaluated.

RESULTS

The repeated measures Skill x Serve Type x Trunk Motion ANOVA for maximal AJ angle indicated no significant main effects for serve type or skill level. However, the AV group had significantly smaller extension (p = 0.018) and greater left lateral flexion (p = 0.038) angles than the AI group. The repeated measures Skill x Serve Type x Phase MANOVA revealed significant phase main effects in all muscles (p < 0.001) and the average EMG of the AV group for LRA was significantly higher than that of the AI group (p = 0.008). All muscles showed their highest EMG values during the acceleration phase. LRA and LEO muscles also exhibited high activations during the descending windup phase, and RES muscle was very active during the follow-through phase.

CONCLUSION

Subjects in the AI group may be more susceptible to back injury than the AV group because of the significantly greater trunk hyperextension, and relatively large lumbar spinal loads are expected during the acceleration phase because of the hyperextension posture and profound front-back and bilateral co-activations in lower trunk muscles.

Lower-limb coordination and shoulder joint mechanics in the tennis serve

PURPOSE

To examine the relationship between variable lower-limb coordination and shoulder joint kinetics and kinematics in the high-performance flat first serve in tennis.

METHODS

Three-dimensional data describing three flat serve (FS) techniques, each executed with varying lower-limb involvement: foot-up (FU), foot-back (FB), and minimal leg drive (ARM), as performed by 12 high-performance male players were recorded using a 12-camera Vicon MX motion analysis system operating at 250 Hz. A discriminant analysis determined the lower-limb kinematics that distinguished serve technique, and by extension, leg drive. A total of 18 one-way ANOVA ascertained statistically significant differences in the kinematic and kinetic variables considered to relate to or represent shoulder joint loading in FU, FB, and ARM serves.

RESULTS

The lower-limb kinematics shown to best discriminate between service techniques were range of rear and front knee joint extension, and peak angular velocity of rear knee joint extension. The forward swings of the FU (43.6 +/- 3.0 m.s(-1), P < 0.05) and FB (42.6 +/- 3.1 m.s(-1), P < 0.05) techniques were characterized by higher peak racket speeds than those generated in the ARM (39.4 +/- 3.4 m.s(-1)) serve. Regardless of stance and leg drive, similar pre- and post-impact shoulder joint kinetics were developed.

CONCLUSION

Knowledge of a server's range of front and rear knee joint extension as well as his/her peak angular velocity of rear knee joint extension is sufficient to ascertain the stance and quality of leg drive used. When facilitated by a leg drive, high-performance players generate similar resultant pre-impact racket velocities independent of stance. With no leg drive, players develop lower resultant racket velocities. Comparable shoulder joint kinetics, however, evolved from the differential lower-limb mechanics that characterized the FU, FB, and ARM techniques.

Shoulder joint loading in the high performance flat and kick tennis serves

OBJECTIVE

To quantify and compare the full body kinematics and shoulder joint kinetics during the high-performance tennis flat (FS) and kick serves (KS).

METHODS

A 12-camera 250 Hz, Vicon motion analysis system recorded the three-dimensional FS and KS of 12 high-performance male players. A total of 22 paired Student's t tests, with an accompanying partial Bonferroni correction (p<0.01), determined statistically significant differences between the variables of interest in both serves.

RESULTS

Higher peak horizontal, vertical and absolute racquet velocities were developed during the FS, while higher lateral velocities characterised the KS. Similar shoulder joint kinematics and kinetics punctuated both serves, but with some variation in trunk and lower limb mechanics.

CONCLUSIONS

Similar shoulder joint kinetics assisted the development of varying three-dimensional racquet velocities in the FS and KS. The comparable shoulder joint loading conditions point to the repetitive, long-term performance of either serve as relevant in shoulder joint injury pathologies.

Phenotypic plasticity and functional asymmetry in response to grip forces exerted by intercollegiate tennis players

This study examined phenotypic and functional responses to extreme asymmetry in hand use, and recorded the grip forces that occur during the tennis serve to assess the forces that contribute to asymmetry. Compressive grip performance was measured for Division I collegiate tennis players (24 female, 24 male) and nonathlete college students (18 females, 17 males) during three experiments: single-repetition maximum voluntary contraction, 30 consecutive repetitions, and a 30-s static hold. Tennis players had significant asymmetry in both forearm circumference and grip strength. The dominant hand of female tennis players produced 25% more force than the opposite hand, while the difference between hands of male tennis players was 18%. However, endurance over 30-repetitions and during the 30-s hold did not significantly differ between the limbs of tennis players. No significant asymmetry in forearm measurements, grip strength, or endurance was detected between the limbs of nonathletes. Grip forces generated during the tennis serve were recorded for 4 male tennis players, using a racket with a dynamometer incorporated into the handle. Peak handgrip forces generated during the serve (150-250 N) averaged 31-44% of the maximum grip force of the participant. Tennis players have increased muscle mass and strength of the dominant limb. Moderate forces, occurring hundreds of times each match and practice, are likely the primary forces contributing to this morphological and functional asymmetry.

Tennis injuries: occurrence, aetiology, and prevention

A systematic search of published reports was carried out in three electronic databases from 1966 on to identify relevant articles relating to tennis injuries. There were 39 case reports, 49 laboratory studies, 28 descriptive epidemiological studies, and three analytical epidemiological studies. The principal findings of the review were: first, there is a great variation in the reported incidence of tennis injuries; second, most injuries occur in the lower extremities, followed by the upper extremities and then the trunk; third, there have been very few longitudinal cohort studies that investigated the association between risk factors and the occurrence of tennis injuries (odds ratios, risk ratios, hazard ratios); and fourth, there were no randomised controlled trials investigating injury prevention measures in tennis. More methodologically sound studies are needed for a better understanding of risk factors, in order to design useful strategies to prevent tennis injuries.

Optimum electrode configuration for detection of leg movement using bio-impedance

Impedances and joint angles were simultaneously measured during ankle and knee movements. The correlation coefficients of the joint angle and the impedance change from human leg movement were obtained using an electro-goniometer and a four-channel impedance measurement system. Because the impedance changes resulting from ankle and knee movements depended heavily on the electrode placement, we determined the optimum electrode configurations for those movements by searching for high correlation coefficients, large impedance changes and minimum interferences in ten subjects (age: 20+/-4). Our optimum electrode configurations showed strong relationships between the ankle joint angle and lower leg impedance (correlation coefficient=-0.91+/-0.06) and between the knee joint angle and knee impedance (correlation coefficient=0.94+/-0.04). The reproducibilities of the impedance changes of five subjects due to the ankle and knee were 6.3+/-1.9% and 5.1+/-1.7% for the optimum electrode pairs, respectively. We propose that this optimum electrode configuration would be useful for future studies involving the convenient measurement of leg movements by the impedance method.

A new approach for detection of leg movement using segmental electrical impedance changes

The purpose of this paper is to provide a new approach for detection using bio-impedance. This impedance is measured by the four-electrode method. As the impedance changes resulting from ankle, knee, and hip movements depend on electrode placement, we determined the optimal electrode configurations for these movements by searching for high correlation coefficients, large impedance changes, and minimum interference in ten subjects (age: 20 +/- 4). Our optimal electrode configurations showed very strong relationships between the ankle joint angle and ankle impedance (gamma = - 0.913 +/- 0.03), between the knee joint angle and knee impedance (gamma = 0.944 +/- 0.02), and between the hip joint angle and hip impedance (gamma = 0.823 +/- 0.08). This study showed that lower leg movement could be easily measured by the impedance measurement system with two pairs of skin electrodes.

Mechanisms of neck and shoulder injuries in tennis players

Shoulder injuries are common among athletes involved in repetitive overhead arm movements, particularly baseball pitchers and tennis players. Due to the similarities between pitching and serving, both athletes often present with similar types of shoulder injuries. However, subtle differences in neck and shoulder movements between the pitcher and tennis player may be responsible for additional mechanisms of injuries specific to tennis players. This paper outlines the similarities and differences between the pitch and serve and discusses how these differences may relate to additional neck and/or shoulder injuries specific to tennis players. In the analyses of mechanisms of injuries sustained by tennis players, such detailed analyses of movement patterns occurring during the serve may optimize a clinician's sports-specific rehabilitation protocol.

Fundamental characteristics of human limb electrical impedance for biodynamic analysis

The paper describes the use of human-limb impedance for biodynamic analysis. The change of human-limb impedance during movement was measured, and was found to be related to kinematic and kinetic parameters. Strong relationships were found between the velocity of change of the forearm impedance and the angular velocity of the elbow joint (correlation coefficient r = -0.97), between the the change of forearm impedance and the velocity of a human limb (r = 0.79). A change of upper-limb impedance was caused by a change in a sectional area of muscular tissue in the measured part and a change of blood volume during movement of an upper limb. In tennis, there was a strong relationship between a change of forearm impedance and ball velocity (r = 0.87). Impedance waveforms were useful for analysis of the movement pattern and the stability of movement in tennis. This method has the following characteristics: (a) it does not have a spatial and temporal limitation for measurement; (b) the subject is scarcely restricted in movement; (c) the data processing can be handled easily and quickly; (d) impedance waveforms inherently show magnitude, form and stability of movement.