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

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

Introduction

The tennis serve is a complex motion with numerous rotations which are important to manage for performance. The main aim of this study was to investigate kinematic parameters, including the evolution of the center of gravity, and kinetic parameters correlated with racket velocity over all phases of the tennis serve. The secondary objective was to find out which of the correlated parameters differed between a slow and a fast serve. The advantage of such an approach would be to propose biomechanical parameters that coaches and teachers could use to optimize performance or learn how to serve.

Methods

Quantitative analysis was carried out on 5 flat serves performed by four ranked players using an optoelectronic system (82 markers located on whole body and racket) composed of 10 infrared cameras (150 Hz) and two force platforms (750 Hz).

Results

A descriptive statistical analysis highlighted 11 very large and almost perfect correlations with racket velocity: vertical ground reaction force of back foot in release backward, trunk axial rotation during loading phase, back and front knee flexions, dominant shoulder and hip mediolateral rotation during cocking phase, and center of gravity vertical velocity, dominant shoulder medial rotation velocity, dominant elbow flexion, trunk flexion/extension and axial rotation during acceleration phase. Differences were observed for some of the correlated parameters between slow and fast serve.

Discussion

Consequently, all these correlated kinematic and kinetics parameters constitute information that coaches, instructors and athletes can use to improve, optimize or teach the tennis serve.

Musculoskeletal Disorder Risk Assessment during the Tennis Serve: Performance and Prevention

Addressing the risk of musculoskeletal disorders (MSDs) during a tennis serve is a challenge for both protecting athletes and maintaining performance. The aim of this study was to investigate the risk of MSD occurrence using the rapid whole-body assessment (REBA) ergonomic tool at each time step, using 3D kinematic analysis of joint angles for slow and fast serves. Two force platforms (750 Hz) and an optoelectronic system including 10 infrared cameras (150 Hz, 82 markers located on the whole body and on the racket) were used to capture the kinematics of the six REBA joint areas over five services in two young male and two young female ranked players. The mean REBA score was 9.66 ± 1.11 (ranging from 7.75 to 11.85) with the maximum value observed for the loading and cocking stage (REBA score > 11). The intermediate scores for each of the six joint areas ranged between 2 and 3 and the maximum value of their respective scales. The lowest scores were observed for the shoulder. Neck rotation and shoulder flexion are parameters that could be taken into account when analyzing performance in the context of MSD prevention.

The Influence of Kinematics on Tennis Serve Speed: An In-Depth Analysis Using Xsens MVN Biomech Link Technology

An inertial measurement system, using a combination of accelerometers, gyroscopes and magnetometers, is of great interest to capture tennis movements. We have assessed the key biomechanical moments of the serve phases and events, as well as the kinematic metrics during the serve, to analyze their influence on serve speed. Eighteen male competitive tennis players, equipped with the inertial measurement units, performed a prolonged serve game consisting of 12 simulated points. Participants were divided into groups A and B in accordance with their positioning above or below the sample average serve speed. Group A (compared with their counterparts) presented with lower back hip adduction and knee flexion, and a higher leftward thoracic tilt during the impact event (-14.9 ± 6.9 vs. 13.8 ± 6.4, 2.8 ± 5.9 vs. 14.3 ± 13.0 and -28.9 ± 6.3 vs. 28.0 ± 7.3°). In addition, group A exhibited higher maximal angular velocities in the wrist and thorax, as well as a lower maximal angular velocity in the back hip than group B (427.0 ± 99.8 vs. 205.4 ± 9.7, 162.4 ± 81.7 vs. 193.5 ± 43.8, 205.4 ± 9.7 vs. 308.3 ± 111.7, 193.5 ± 43.8 vs. 81.1 ± 49.7°/s). The relevant biomechanical differences during the serve were identified, highlighting the changes in joint angles and angular velocities between the groups, providing meaningful information for coaches and players to improve their serve proficiency.

Kinematics characteristics of key point of interest during tennis serve among tennis players: a systematic review and meta-analysis

The objective of this systematic review and meta-analysis was to provide an overview of kinematic parameters associated with key points of interest in the tennis serve. The research was conducted according to the PRISMA guideline without date restriction. Google scholar, Science Direct, PubMed/Medline, Mendeley, and Science.gov databases were scanned to find relevant studies. Only English peer-review original article focused on joint body angles at trophy position, racket low point and ball impact were retained. The review, quality appraisal, and data extraction from selected studies were performed independently by two reviewers. A meta-analysis was carried out on the most studied joint parameters. Among the 2,844 records identified, 27 articles were included. The wide variety of methods used required data homogenization for comparison purposes. Trunk inclination (25.0 ± 7.1°) and front knee flexion (64.5 ± 9.7°) were the most studied parameters for trophy position. Shoulder lateral rotation (130.1 ± 26.5°) was systematically evaluated for racket low point. At ball impact, shoulder elevation (110.7 ± 16.9°) and elbow flexion (30.1 ± 15.9°) were the most considered joint angles. The systematic review revealed that many kinematic parameters were not quantified at the various key points of interest. Knowledge of the kinematics is essential for understanding the gesture, implementing training methods, and improving the performance.

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

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

Neuromuscular Fitness Is Associated with Serve Speed in Young Female Tennis Players

In tennis, the serve plays a key role in determining the success of a player. The speed of a serve is influenced by a multitude of interconnected skills and abilities. The objective of this study was to establish the correlation between the explosive strength of the throwing type, the grip strength and flexibility of the arms, and the shoulder girdle with the serve speed in young female tennis players. Additionally, the study aimed to develop a regression model that accurately predicts the serve speed by analyzing the interplay among these variables. The study was carried out on a group of 20 tennis players, who had an average age of 13.10 ± 0.74 years. Additionally, their height was recorded as 165.70 ± 4.90 cm, and their body mass was measured at 51.45 ± 5.84 kg. To assess the motor abilities of the upper extremities, four tests were used that aimed to measure the explosive strength of the throwing type; one test was for the strength of the hand and forearm muscles, and one test was for the flexibility of the arms and shoulder girdle. Of all the variables examined, the medicine ball throw shot put (MBTSP) (r = 0.75), overhead medicine ball throw (OMBT) (r = 0.70), and grip strength (GS) (r = 0.71) displayed a notable correlation with serve speed (p < 0.05). The results obtained from the multiple regression analysis indicate that the combination of selected predictors (MBTSP-medicine ball throw shot put, OMBT-overhead medicine ball throw and GS-grip strength) explained 75% of the variability in serve speed. Significantly, MBTSP surfaced as the predominant predictor, autonomously elucidating 51% of the variability in serve speed. The importance of improving the analyzed motor skills of young female tennis players to enhance their serve in terms of speed is emphasized by the findings of this research.

Upper limb functional testing in athletes: A Delphi study

Background

Functional testing has recently become more and more popular to assess athletes, both for injury prevention, as well as in an objective of performance. However, the relationship between the results of these tests and performances (or injuries) or their interpretation remains unclear.

Objective

The aim of this study is to explore the usefulness, the characteristics, and the interpretation of the most frequently used upper-limb functional test.

Methods

Twenty-two experts with an excellent knowledge of upper limb functional tests and an expertise in sports medicine and/or sports training of at least 5 years were recruited. They answered to qualitative and quantitative questions about functional testing trough structured questionnaires (online).

Results

Four rounds were needed to reach a consensus about the usefulness as well as the characteristics of each test. Different sports-specific batteries of tests were also suggested by the experts and reached consensus. However, concerning the interpretation of the test, a consensus was only found for half of the tests considered.

Conclusion

The current study summarizes the characteristics and the usefulness of the most popular upper-limb functional tests. However, the interpretation of some tests will have to be further explored since no consensus was found for them.

Biophysical characterization of the tennis serve: A systematic scoping review with evidence gap map

OBJECTIVES

We aimed to assess the available evidence on the biophysics of the tennis serve, mapping the populations, interventions, contexts and other relevant information to highlight what is already known and to identify gaps in the literature.

DESIGN

Systematic scoping review with evidence gap map.

METHODS

The protocol was designed according to PRISMA 2020, Prisma-ScR guidelines and the Cochrane Handbook. The searches were conducted on July 20, 2022 and updated on April 1, 2023, in PubMed, Scopus and Web of Science (core collection). The risk of bias assessment was performed using the Cochranes method for nonrandomized studies (RoBANS) and a narrative synthesis of the main findings was performed and supplemented with an evidence gap map.

RESULTS

Most trials were found on serve kinematics and kinetics (95 %), analyzing only flat serves (84 and 72 %, respectively). Few trials focused on physiology (20 %; e.g. biomarkers), under-19, left or both-handed, female and intermediate beginner or starter players (29, 17, 8 and 7 %, respectively). We found a preponderance of low and unclear risk of bias (63 and 31 %, respectively) and only 7 % high, particularly, on the assessment of confounding variables.

CONCLUSIONS

The current scoping review reveals a few trials on physiological rather than biomechanical variables, as well as the absence of the kick and slice serve, foot-back and foot-up serve, and left-handed, female, and young player analyses. We did not find systematic mistakes or limitations in the design, conduct, or analysis that would distort the results, since only 7 % presented a high risk of bias.

Is isokinetic shoulder strength a determinant of serve ball velocity in tennis?

The tennis serve is closely related to the quality of the tennis match. However, the isokinetic parameters associated with the tennis serve are still unclear. The aim of this study was to investigate the relationships between ball velocity and isokinetic shoulder strength in tennis serve and to determine isokinetic strength parameters that can predict tennis serve velocity. A total of 13 elite male athletes (16.8 ± 1.5 years) voluntarily participated in the study. The athletes' shoulder internal-external rotation, extension-flexion and abduction-adduction strengths were measured with 5-5-15 repetitions at 60°/s, 180°/s, 240°/s angular velocities. Later, the athletes' 1st, 2nd, and average serve ball speeds were determined using a handheld radar gun. Significant correlations were found between ball speed and isokinetic tennis serve strength (r = 0.556-0.819; p < 0.05). The correlations between ball speed and isokinetic strength performance were higher at 180°/s and 240°/s angular velocities. Extension (240°/s; r = 0.819), flexion (180°/s; r = 0.755), abduction (240°/s; r = 0.733), adduction (240°/s; r = 0.684) and internal rotation (180°/s; r = 0.803) were highly correlated with ball velocity. These findings suggest that strength training to increase the ball speed of the tennis serve should be performed fast at high angular velocities and planning should focus on the strength of extension, flexion, abduction, adduction and internal rotation.

Comparison of the activation and mechanical properties of scapulothoracic muscles in young tennis players with and without scapular dyskinesis: an observational comparative study

BACKGROUND

In tennis athletes with scapular dyskinesis, the activation of the scapulothoracic muscles during serve is not known. Also, the mechanical properties (tone, elasticity, and stiffness) of the scapulothoracic muscles of the tennis athletes with scapular dyskinesis are likely to change. The study aimed to evaluate the activation of the scapulothoracic muscles while performing tennis serve and to determine the changes in the mechanical properties of the same muscles in young tennis athletes with scapular dyskinesis.

METHODS

Seventeen tennis athletes with scapular dyskinesis aged between 11 and 18 years (the scapular dyskinesis group) and age- and gender-matched 17 asymptomatic tennis athletes (the control group) were included in the study. Activation of scapulothoracic muscles (descending-transverse-ascending trapezius and serratus anterior) in the 3 phases (preparation, acceleration, and follow-through) of the serve was evaluated using surface electromyography, and the mechanical properties of the same muscles were measured at rest by myotonometry.

RESULTS

Ascending trapezius activation in the follow-through phase was lower in the scapular dyskinesis group compared with the control group (mean difference 95% confidence interval: -22.8 [-41.2 to -4.5]) (P = .017). The tone and stiffness of the transverse trapezius (P = .043 and P = .017, respectively) were higher, whereas the same parameters of the ascending trapezius were lower (P = .008 and P = .010, respectively) in the scapular dyskinesis group compared with the control group.

CONCLUSIONS

Activation of the ascending trapezius and the tone and stiffness of the transverse-ascending trapezius were altered in tennis athletes with scapular dyskinesis. Implementations to improve these changes can be included in the rehabilitation or training programs of young tennis athletes with scapular dyskinesis.

The expert eye? An inter-rater comparison of elite tennis serve kinematics and performance

This study examined the reliability of expert tennis coaches/biomechanists to qualitatively assess selected features of the serve with the aid of two-dimensional (2D) video replays. Two expert high-performance coaches rated the serves of 150 male and 150 female players across three different age groups from two different camera viewing angles. Serve performance was rated across 13 variables that represented commonly investigated and coached (serve) mechanics using a 1-7 Likert rating scale. A total of 7800 ratings were performed. The reliability of the experts' ratings was assessed using a Krippendorffs alpha. Strong agreement was shown across all age groups and genders when the experts rated the overall serve score (0.727-0.924), power or speed of the serve (0.720-0.907), rhythm (0.744-0.944), quality of the trunk action (0.775-1.000), leg drive (0.731-0.959) and the likelihood of back injury (0.703-0.934). They encountered greater difficulty in consistently rating shoulder internal rotation speed (0.688-0.717). In high-performance settings, the desire for highly precise measurement and large data sets powered by new technologies, is commonplace but this study revealed that tennis experts, through the use of 2D video, can reliably rate important mechanical features of the game's most important shot, the serve.

Effects of modified sleeper stretch and modified cross-body stretch on upper limb functions and shoulder ROM in tennis players: a randomized trial

Tennis players often experience posterior shoulder pain due to restricted internal rotation (IR) range of motion (ROM) of the glenohumeral joint. No research has compared the effects of modified sleeper stretch (MSS) versus modified cross-body stretch (MCBS) on tennis players' upper limb functions and IR ROM. The study aimed to compare the efficacy of modified sleeper and cross-body adduction stretch in improving shoulder IR ROM and upper limb functions in tennis players. Thirty male lawn tennis players (aged 20 to 35 years) with more than 15° glenohumeral IR deficiency on the dominant side compared to the non-dominant side were recruited and divided into two groups: Modified sleeper stretch group (MSSG) and modified cross-body stretch group (MCBSG). MSSG received MSS, and MCBSG received MCBS, 3-5 repetitions once daily for 4 weeks. Upper limb functions were measured using the Disability of the Arm, Shoulder, and Hand (DASH) scale, and the IR ROM of the shoulder joint was measured using a universal goniometer. Both groups observed significant (p < 0.05) DASH scores and IR ROM improvements. DASH scores decreased by 85% in MSSG and 79.60% in MCBSG. IR ROM increased by 94.64% in MSSG and 89.52% in MCBSG. No significant differences (p > 0.05) were found in post-intervention DASH scores and IR ROM values between both groups. MSS and MCBS improved upper limb functions and IR ROM of the shoulder joint in the selected sample population of lawn tennis players. No difference was observed between both stretching techniques in improving upper limb functions and IR ROM of the shoulder joint.

Joint-specific Postactivation Potentiation Enhances Serve Velocity in Young Tennis Players

ABSTRACT

Baiget, E, Colomar, J, and Corbi, F. Joint-specific postactivation potentiation enhances serve velocity in young tennis players. J Strength Cond Res 37(4): 840-847, 2023-This study aimed (a) to analyze the influence of sport-specific postactivation potentiation (PAP) on serve velocity (SV) and serve accuracy (SA) in young tennis players, (b) to compare the PAP effects of 2 different conditioning activities (CA) on SV and SA, and (c) to explore if changes in SV would be related to tennis player's neuromuscular performance. Sixteen competition young tennis players performed 3 testing sessions in a randomized order. In the control session, subjects performed a warm-up protocol followed by the SV and SA tests. The experimental sessions involved 1 (shoulder internal rotation [SHIR]) or 2 (SHIR + shoulder flexion [SHF]) repetitions of a 5 second maximal voluntary isometric contraction (MVIC) executed before the SV and SA tests. Results showed a moderate significant (p = 0.037) difference between SV at control session and following the SHIR + SHF CA protocol at minute 0 (3.4 ± 4.6%; 4.6 km·h-1; ES = 0.711). Serve accuracy did not differ between CA protocols and control session at any time point. No significant relations were found between force-time curve parameters and SV percent changes at different recovery times. Performing 2, short (5 seconds), upper-limb, tennis joint-specific MVIC seems to enhance SV without negatively affecting SA in young competition tennis players. On the contrary, performing one MVIC does not seem to obtain the same effects. Moreover, tennis players with improved neuromuscular performance do not seem to exhibit a better predisposition to postactivation performance enhancement.

Differentiating Stroke and Movement Accelerometer Profiles to Improve Prescription of Tennis Training Drills

ABSTRACT

Perri, T, Reid, M, Murphy, A, Howle, K, and Duffield, R. Differentiating stroke and movement accelerometer profiles to improve prescription of tennis training drills. J Strength Cond Res 37(3): 646-651, 2023-This study compared the movement- and stroke-related accelerometer profiles and stroke counts between common on-court tennis training drills. Ten, junior-elite, male tennis players wore a cervical-mounted global positioning systems, with in-built accelerometer, gyroscope, and magnetometer during hard court training sessions ( n = 189). Individual training drills were classified into 8 categories based on previous research descriptions. Manufacturer software calculated total player load (tPL), while a prototype algorithm detected forehand (FH), backhands (BH), and serves and then calculated a stroke player load (sPL) from individual strokes. Movement player load (mPL) was calculated as the difference between tPL and sPL. Drill categories were compared for relative ( . min -1 ) tPL, sPL, mPL, and stroke counts via a 1-way analysis of variance with effect sizes (Cohen's d ) and 95% confidence intervals. Highest tPL . min -1 existed in accuracy and recovery or defensive drills ( p < 0.05), with lowest tPL·min -1 values observed in match-play simulation ( p < 0.05). For sPL·min -1 , accuracy drills elicited greater values compared with all other drill types ( p < 0.05), partly via greater FH-sPL·min -1 ( p < 0.05), with lowest sPL·min -1 existing for match-play ( p < 0.05). Accuracy, open, and recovery or defensive drills result in greater BH-sPL·min -1 and BH . min -1 ( p < 0.05). Serve-sPL·min -1 is highest in technical and match-play drills ( p < 0.05). Higher mPL·min -1 existed in accuracy, recovery or defensive, 2v1 net, open, and 2v1 baseline ( p < 0.05). Furthermore, mPL·min -1 in points drills was greater than technical and match-play simulation drills ( p < 0.05). Higher hitting-based accelerometer loads (sPL·min -1 ) exist in accuracy drills, whereas technical and match-play drills show the lowest movement demands (mPL·min -1 ). These findings can aid individual drill prescription for targeting movement or hitting load.

Effects of an 8-week multimodal program on thoracic posture, glenohumeral range of motion and serve performance in competitive young tennis players

Introduction

Intensive tennis practice is known to generate sport-specific adaptations at the shoulder region and influence the sagittal spinal curvature. However, increased thoracic kyphosis decreases the shoulder functional capacity, which could limit tennis performance. Therefore, the aim of this study was to investigate the effects of an 8-week multimodal program on thoracic posture, glenohumeral range of motion, and serve performance in competitive young tennis players.

Methods

Eighteen male and four female players (age: 16.0 ± 2.4 years, height: 170.7 ± 11.0 cm; mass: 62.1 ± 11.5 kg; International Tennis Number: 3-4) performed their regular training during 8 weeks, which was used as a reference period, and implemented a multimodal program including stretching, strengthening, and myofascial release exercises, four times per week during 8 additional weeks, which corresponded to the intervention period. The thoracic curvature angle and mobility, the biacromial and interscapular distances, the glenohumeral range of motion and the tennis serve performance were assessed three times, i.e., before and after the regular training and after the 8-week multimodal program.

Results

The results showed that the 8-week regular training had no significant effects on thoracic curvature angle [effect size (ES) = 0.02-0.36, p = 0.06-0.46] and mobility (ES = 0.05-0.26, p = 0.13-0.42), biacromial (ES = 0.05, p = 0.18) and interscapular distances (ES = 0.03, p = 0.45), ranges of motion in glenohumeral internal (ES = 0.04, p = 0.43) and external rotation (ES = 0.43, p = 0.06), and tennis serve accuracy (ES = 0.33, p = 0.07) and velocity (ES = 0.09, p = 0.35). The 8-week multimodal program increased moderately the thoracic mobility (ES = 0.55, p = 0.01), moderately to strongly the serve accuracy and velocity (ES = 0.65, p = 0.003, for both), strongly decreased the interscapular distance (ES = 1.02, p < 0.001), and strongly increased the range of motion in glenohumeral internal (ES = 0.90, p < 0.001) and external rotation (ES = 1.49, p < 0.001).

Discussion

These findings indicated that an 8-week multimodal program, including spine and glenohumeral mobility and shoulder girdle strength exercises, performed four times per week during 8 weeks, is moderately relevant to rectify the sagittal thoracic curvature in competitive tennis players, while such a program may help regain the range of motion in glenohumeral rotation without tennis serve performance impairment.

Influence of anthropometric, ball impact and landing location parameters on serve velocity in elite tennis competition

This study aimed (i) to analyse the associations between serve velocity (SV) and anthropometric, ball impact and landing location parameters in total serves (TS) and fastest serves (FS) performed during an ATP Tour event; (ii) to observe differences between first (S1) and second (S2) serves, and (iii) to determine a SV prediction model based on the relationship between the observed variables. Using Foxtenn technology, 30 S1 and 15 S2 were registered in 14 matches in twenty-one male professional tennis players. Ball impact (impact height [IH], impact projection angle [IPA] and relative impact height [RIH]), bounce landing (width and depth) location parameters, S1 and S2 SV in TS (TSV1 and TSV2) and FS (FSV1 and FSV2) alongside anthropometric characteristics of tennis players (body height [BH], body mass [BM] and body mass index [BMI]) were analysed. Significant moderate to large associations were found between BH and BM and TSV1, FSV1 and FSV2 (r = 0.315 to 0.593; p < 0.001), and between IH and IPA and TSV1 and TSV2 (r = 0.294 to -0.409; p < 0.001). BH and BM were the unique significant contributors of FS explaining 22 to 35% of FSV1 and FSV2. Only BM appears in the model to predict FSV1 and FSV2 (r² = 0.48 and 0.21). We concluded that all three anthropometric, ball impact and bounce landing location parameters small to moderately influence TSV. Anthropometric parameters show an impact on SV when tennis players serve at or near maximal speed, highlighting the influence of BM above BH.

Biomechanical estimation of tennis serve using inertial sensors: A case study

Inertial measurement units may provide a relevant on-court 3-Dimension measurement system for tennis serve biomechanical analysis. Therefore, this case study aimed to report the feasibility of inertial measurement unit's kinematic and kinetic data collection during tennis serve. Two injury-free highly-trained tennis players were equipped with the inertial measurement unit (Xsens MVN suit) and performed 2 trials of five flat “first” serves on a 1 m2 target zone bordering the service box of an indoor GreenSet® tennis court surface. With the exception of the center of gravity rotation at the loading stage, all joint (shoulder, elbow, knee) angles, center of mass displacements and rotations followed a similar development for both female and male participants from loading to finish stages. At ball contact stage, articular moments (mid-trunk, upper-trunk, shoulder, elbow, wrist) and segmental contribution (pelvis linear, pelvis rotation, trunk, shoulder, elbow, wrist) repartitions also showed a comparable movement. From loading to finish stages, total, lower and upper energy contribution were similar for both players, with coefficient of variations deemed acceptable between the two trials. This inertial measurement unit appears suitable for on-court tennis serve biomechanical data collection and subsequent analysis to provide tennis players and practitioners tailored feedbacks to facilitate motor learning process and develop serve efficiency.

Age and Gender Differences in Injuries and Risk Factors in Elite Junior and Professional Tennis Players

BACKGROUND

Elite tennis athletes experience injuries throughout the entire body. Impairments in trunk stability, lower limb flexibility, and hip range of motion (ROM) are modifiable risk factors that can impact injuries and performance. Information on nonmodifiable risk factors such as age and gender is limited. The purpose of this investigation was to provide information on risk factors to direct clinical decision-making and injury prevention and rehab programming in this population.

HYPOTHESIS

Prevalence and location of injuries will differ by age group and gender. Trunk stability, lower limb flexibility, and hip ROM will differ by age group and gender.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A de-identified database (n = 237; females = 126) from the United States Tennis Association High Performance Profile (HPP) 2014-2015 was used for the analysis. Subjects were elite junior and professional tennis players (mean age 14.6 [range, 9-27] years). The HPP is a tennis-specific assessment and questionnaire that includes retrospective information on injury history. Subjects were categorized by injury, gender, and age. Injury locations were classified by region. Trunk stability measures included drop vertical jump (DVJ), single-leg squat, and prone and side planks. Lower limb measures included hamstring, quadriceps and hip flexor flexibility, and hip rotation ROM.

RESULTS

A total of 46% of athletes reported an injury. Significant differences were found for injury prevalence and location by age group. Adolescent athletes (age 13-17 years) had more trunk injuries, while adult athletes (age ≥18 years) had more lower limb injuries. Adolescent athletes performed worse on DVJ, dominant side plank, and hamstring flexibility compared with young (age ≤12 years) and adult athletes. Significant gender differences in hip ROM included internal rotation on both the dominant and nondominant sides.

CONCLUSION

Impairments in trunk stability, lower limb flexibility, and hip rotation ROM may affect both health and performance outcomes in this population. Elite tennis athletes may benefit from additional off court programming to address trunk and lower limb impairments.

CLINICAL RELEVANCE

Adolescent elite tennis athletes may be at higher risk of trunk injuries. Age, gender, injury history, and impairments should be considered with all assessments and programming.

Upper-Limb Force-Time Characteristics Determine Serve Velocity in Competition Tennis Players

PURPOSE

(1) To analyze the associations between serve velocity (SV) and various single-joint upper-limb isometric force-time curve parameters, (2) to develop a prediction model based on the relationship between these variables, and (3) to determine whether these factors are capable of discriminating between tennis players with different SV performances.

METHOD

A total of 17 high-performance tennis players performed 8 isometric tests of joints and movements included in the serve kinetic chain (wrist and elbow flexion [EF] and extension; shoulder flexion [SHF] and extension [SHE], internal [SHIR] and external rotation). Isometric force (IF), rate of force development (RFD), and impulse (IMP) at different time intervals (0-250 ms) were obtained for analysis.

RESULTS

Significant (P < .05 to P < .01) and moderate to very large correlations were found between SV and isometric force (IF), RFD and impulse (IMP) at different time intervals in all joint positions tested (except for the EF). Stepwise multiple regression analysis highlighted the importance of RFD in the SHIR from 0 to 50 milliseconds and isometric force (IF) in the SHF at 250 milliseconds on SV performance. Moreover, the discriminant analyses established SHIR RFD from 0 to 30 milliseconds as the most important factor discriminating players with different serve performances.

CONCLUSIONS

Force-time parameters in upper-limb joints involved in the serve moderate to very largely influence SV. Findings suggest that the capability to develop force in short periods of time (<250 ms), especially in the shoulder joint, seems relevant to develop high SV in competition tennis players.

External Training Load and the Association With Back Pain in Competitive Adolescent Tennis Players: Results From the SMASH Cohort Study

Background:

In young tennis players, high loads on the spine and high training volumes in relation to age are associated with a high lifetime prevalence of back pain. The primary aim of this study was to investigate if accumulated external workload “spikes” in the acute:chronic workload ratio (ACWR) of tennis training, match play, and fitness training, and if high or low workload/age ratio were associated with back pain events in competitive adolescent tennis players. Additional aims were to report the incidence of back pain stratified by sex and level of play and to describe the characteristics of players with back pain.

Hypothesis:

Rapid increases in external workload are associated with the incidence of back pain.

Study Design:

Cohort study of 198 competitive tennis players, 13 to 19 years, with a weekly follow-up for 52 consecutive weeks.

Level of Evidence:

Level 3.

Methods:

Accumulated external workload spikes (uncoupled ACWR >1.3), and the workload/age ratio, were time-varying exposures in Cox regression analyses with the outcome back pain (pain intensity ≥2/10 in the lower back and/or in the upper back/neck with a pain-related disability).

Results:

For each additional workload spike in tennis training/match play, the hazard rate ratio (HRR) was 1.17 (95% CI, 1.06-1.28) for back pain. The corresponding HRR for fitness training was 1.13 (95% CI, 1.05-1.22). Training workload/age ratio was not related to back pain.

Conclusion:

Accumulated external workload spikes of tennis training, match play, and/or fitness training are associated with a higher rate of back pain events in competitive adolescent tennis players.

Clinical Relevance:

Back pain is a troublesome clinical problem that may affect the performance of talented young tennis players. Structuring the training schedule to minimize rapid increases (ie, spikes) of training load on a weekly basis may enhance performance and reduce back pain in adolescent tennis players.

Kinematic characteristics of the tennis serve from the ad and deuce court service positions in elite junior players

PURPOSE

According to the official rules of the International Tennis Federation, players have to serve alternately from two different positions: the deuce (right, D) and the ad court (left, AD) side. This study aimed to compare body and ball kinematics of flat serves from both service sides.

METHODS

In a controlled, semi-court laboratory setting, 14 elite male junior players served eight flat first serves to a target field directed to the receiver's body from both service positions in a matched and counterbalanced order. An 8-camera-Vicon-System was used to capture the 3D-landmark trajectories.

RESULTS

The mean service velocity was found to be similar on both sides (D: 151.4 ± 19.8 vs. AD: 150.5 ± 19.4 km/h), while multiple characteristics of the serve and ball kinematics differed significantly (p < .05). At starting, the front-foot angle relative to the baseline (D: 39.7±17.6° vs. AD: 31.1±17.4°) and lateral distance between the feet (D: 16.3 ± 12.9 cm vs. AD: 26.2 ± 11.9 cm) were significantly different. During the service, upper torso range of motion from maximum clockwise rotation until impact was significantly greater on the deuce court (D: 130.5 ± 19.8° vs. AD: 126.7 ± 21.1°). This was especially pronounced in foot-back technique players. Further, differences in the lateral ball impact location (D: 30.0 ± 24.1 cm vs. AD: 10.3 ± 23.3 cm) were observed.

CONCLUSIONS

Changing the service side affects the serve and ball kinematics in elite junior tennis players. Our results underline biomechanical differences regarding the starting position (feet and upper torso) as well as the movement and ball kinematics which could be relevant for skill acquisition, injury prevention and performance enhancement.

Bone Microarchitecture and Strength Adaptation to Physical Activity: A Within-Subject Controlled HRpQCT Study

PURPOSE

Physical activity benefits bone mass and cortical bone size. The current study assessed the impact of chronic (≥10 yr) physical activity on trabecular microarchitectural properties and microfinite element analyses of estimated bone strength.

METHODS

Female collegiate-level tennis players (n = 15; age = 20.3 ± 0.9 yr) were used as a within-subject controlled model of chronic unilateral upper-extremity physical activity. Racquet-to-nonracquet arm differences at the distal radius and radial diaphysis were assessed using high-resolution peripheral quantitative computed tomography. The distal tibia and the tibial diaphysis in both legs were also assessed, and cross-country runners (n = 15; age = 20.8 ± 1.2 yr) included as controls.

RESULTS

The distal radius of the racquet arm had 11.8% (95% confidence interval [CI] = 7.9% to 15.7%) greater trabecular bone volume/tissue volume, with trabeculae that were greater in number, thickness, connectivity, and proximity to each other than that in the nonracquet arm (all P < 0.01). Combined with enhanced cortical bone properties, the microarchitectural advantages at the distal radius contributed a 18.7% (95% CI = 13.0% to 24.4%) racquet-to-nonracquet arm difference in predicted load before failure. At the radial diaphysis, predicted load to failure was 9.6% (95% CI = 6.7% to 12.6%) greater in the racquet versus nonracquet arm. There were fewer and smaller side-to-side differences at the distal tibia; however, the tibial diaphysis in the leg opposite the racquet arm was larger with a thicker cortex and had 4.4% (95% CI = 1.7% to 7.1%) greater strength than the contralateral leg.

CONCLUSION

Chronically elevated physical activity enhances trabecular microarchitecture and microfinite element estimated strength, furthering observations from short-term longitudinal studies. The data also demonstrate that tennis players exhibit crossed symmetry wherein the leg opposite the racquet arm possesses enhanced tibial properties compared with in the contralateral leg.

Tennis overuse injuries in the upper extremity

OBJECTIVE

Tennis is a popular sport with high levels of participation. This article aims to describe how upper extremity overuse injuries occur in relation to tennis biomechanics and to review their imaging characteristics and implications for management. In particular, we will review the imaging patterns of internal impingement, scapular dyskinesis, lateral and medial epicondylitis, ulnar collateral ligament insufficiency, valgus extension overload, capitellar osteochondritis dissecans, extensor carpi ulnaris tendinosis and instability, tenosynovitis, triangular fibrocartilage complex injuries, and carpal stress injuries.

CONCLUSION

Tennis is a complex and physically demanding sport with a wide range of associated injuries. Repetitive overloading commonly leads to injuries of the upper extremity. An understanding of the underlying mechanisms of injury and knowledge of these injury patterns will aid the radiologist in generating the correct diagnosis in both the professional and recreational tennis athlete.

Relationship Between Tennis Serve Velocity and Select Performance Measures

ABSTRACT

Hayes, MJ, Spits, DR, Watts, DG, and Kelly, VG. Relationship between tennis serve velocity and select performance measures. J Strength Cond Res 35(1): 190-197, 2021-The purpose of this study was to determine whether there was a relationship between tennis serve speed and isometric midthigh pull (IMTP) kinetic variables: countermovement jump (CMJ) height, shoulder internal and external rotation strength, and anthropometric measures in elite adolescent tennis players. Twenty-one elite junior tennis players from the Tennis Australia National Academy were recruited for this study (male, n = 12 and female, n = 9). Correlations between the performance variables and peak tennis serve speed were calculated using a Pearson's product-moment correlation coefficient. A significant positive correlation was found between peak serve speed and body height (r = 0.80, p < 0.01), IMTP peak force (r = 0.87, p < 0.01), CMJ height (r = 0.77, p ≤ 0.01), and impulse at 300 ms (r = 0.71, p ≤ 0.01). A significant, strong correlation was found between peak serve speed and impulse at 100 ms (r = 0.58, p ≤ 0.01), impulse at 200 ms (r = 0.64, p ≤ 0.01), internal rotation <90° (r = 0.63, p ≤ 0.01), and external rotation <90° (r = 0.63, p ≤ 0.01). Because of the significant positive correlations between IMTP variables, CMJ height and peak serve speed, strength and conditioning coaches with access to a force plate should consider using the IMTP to athletically profile athletes in regards to their strength, power, and injury risk.

Metabolic Demands, Center of Mass Movement and Fractional Utilization of V ˙ O 2 max in Elite Adolescent Tennis Players During On-Court Drills

The aim of the study was to investigate the exercise intensity and energy expenditure during four types of on-court tennis drills. Five female and five male tennis players participated in the study (age: 17 ± 2 years; V∙O2max: 54 ± 6 ml·kg⁻¹·min⁻¹). Anthropometric measures were taken for each player and, on separate days, each player performed (i) treadmill running to determine V∙O2max and (ii) four different tennis drills (Drill1-4) during which V∙O2, blood lactate concentration, ratings of perceived exertion (RPE 6–20), and displacement of center of mass (m) using 3D kinematics were recorded. The drills were designed to simulate match play with 90 s of rest between each drill. A repeated two-way ANOVA was used for physiological and biomechanical data and Friedman's test for RPE using < α 0.05. Fractional utilization of V∙O2max was greatest during Drill1 81.8 ± 7.0% and lowest during Drill4 72.4 ± 5.2% (p < 0.001) with no difference between sexes (p > 0.05). The highest energy expenditure was during Drill1 and lowest during Drill4 (77 ± 15 and 49 ± 11 kcal, respectively, p < 0.05). Energy expenditure per meter for Drill1–Drill4 was subsequently reduced for each drill with 10.5 ± 2.1, 9.9 ± 2.2, 7.6 ± 1.7, and 8.0 ± 1.6 J·kg⁻¹·m⁻¹ (p < 0.01). There were no interaction effects for any of these variables. RPE (6–20) and blood lactate concentration post Drill1–Drill4 were 17.5, 15.5, and 13.0 (overall, legs and arms, p < 0.001) and 5.9 ± 2.0, 4.9 ± 1.9, 5.6 ± 2.0, and 5.0 ± 2.2 mmol·l⁻¹ (p < 0.05). The findings of this study demonstrate that the on-court tennis drills performed here are suitable for high intensity training in junior tennis players. The energy expenditure per minute is comparable to similar sports whereas the energy expenditure per meter is notably greater.

Visual Observation of Apparent Infraspinatus Muscle Atrophy in Male Professional Tennis Players

Background:

Previous studies have reported visually observed apparent muscle atrophy in the infraspinous fossa of the dominant arm of overhead athletes. Several mechanisms have been proposed as etiological factors, including eccentric overload, compressive spinoglenoid notch paralabral cysts, and cumulative tensile suprascapular neurapraxia.

Purpose:

To report the prevalence of apparent infraspinatus atrophy in male professional tennis players and to determine whether the suspected atrophy correlates with objectively measured weakness of external rotation.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 153 male professional tennis players underwent a musculoskeletal screening examination that included visual inspection of the infraspinous fossa. Infraspinatus atrophy was defined as hollowing or loss of soft tissue bulk inferior to the scapular spine in the infraspinous fossa of one extremity that was visibly different from the contralateral extremity. This finding was observed and independently agreed upon by both an orthopaedic surgeon and a physical therapist during the examination. Also assessed were rotator cuff instrument-assisted manual muscle testing, visual observation of scapular kinesis (or motion), and glenohumeral joint range of motion for internal and external rotation and horizontal adduction.

Results:

In the 153 players, dominant-arm infraspinatus atrophy was observed in 92 players (60.1%), and only 1 player (0.7%) was identified with nondominant infraspinatus atrophy. A Pearson correlation showed a significant relationship between the presence of dominant-arm infraspinatus atrophy and dominant-arm external rotation strength measured in neutral abduction/adduction (at the side) (P = .001) as well as between the presence of dominant-arm infraspinatus atrophy and bilateral external rotation strength measured at 90° of glenohumeral joint abduction (P = .009 for dominant arm and .002 for nondominant arm). No significant correlation was found with scapular dyskinesis, glenohumeral range of motion, or instrument-assisted manual muscle testing of the supraspinatus (empty-can test).

Conclusion:

Visually observed infraspinatus muscle atrophy is a common finding in the dominant shoulder of asymptomatic male professional tennis players and is significantly correlated with external rotation weakness. This condition is present in uninjured players without known shoulder pathology and is not related to glenohumeral joint internal rotation, total rotation range of motion, or scapular dysfunction. Players with visually observed infraspinatus atrophy should be evaluated for external rotation strength and may require preventive strengthening.

Scapular Dyskinesis and the Kinetic Chain: Recognizing Dysfunction and Treating Injury in the Tennis Athlete

PURPOSE OF REVIEW

This article aims to provide a comprehensive understanding of the evaluation, diagnosis, and management of scapular dyskinesis and its impact on the kinetic chain in tennis athletes.

RECENT FINDINGS

Optimal glenohumeral biomechanics are intimately associated with proper scapular motion and function. The tennis serve requires the scapula to act as a force transducer in the kinetic chain to convert potential energy generated in the lower extremities to kinetic energy in the upper extremity. Any aberration within this complex kinetic chain will result in force uncoupling and increases the potential for injury through compensatory mechanisms. Specifically, scapular dyskinesis has been associated with an increased risk of shoulder pain of up to 43% in overhead athletes. These pathologies include rotator cuff disease, subacromial and posterior impingement, labral injuries, and SLAP tears. Although the direct causality of these injuries remains controversial, multiple kinematic studies have demonstrated altered scapular positioning increasing the predilection for soft tissue pathology. The diagnosis of scapular dyskinesis is predicated upon a thorough history, physical examination, and observational analysis of key nodes in the kinetic chain during tennis activity. Conservative management remains the mainstay of treatment and consists of a graduated physical therapy regimen. Although shoulder pain in the overhead athletes is often multifactorial, early recognition and treatment of scapular dyskinesis generally carry a favorable prognosis and result in improved patient outcomes.

Repetitive Traumatic Discopathy in the Modern-Era Tennis Player

Degenerative disc disease is more prevalent among athletes than the general population. Repetitive traumatic discopathy is a pattern of injury that has been described in athletes participating in sports that impart repetitive mechanical forces on the lumbar spine. Hence, tennis players may be particularly susceptible to repetitive traumatic discopathy due to the fast-paced nature of the modern tennis match. Recent biomechanical studies have identified the lumbar spine as the focal point of motion during tennis strokes, and the lumbar spine is notably the most frequent location of injury observed in tennis players. In this comprehensive review, we examine current evidence and discuss the epidemiology, pathophysiology, biomechanics, diagnosis, and treatment of repetitive traumatic discopathy in tennis players. Additionally, we outline considerations for rehabilitation and return to the tennis court after operative management.

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.

Step by Step Guide to Understanding the Kinetic Chain Concept in the Overhead Athlete

PURPOSE OF REVIEW

The purpose of this review will be to provide both a historical and recent review of the role of the kinetic chain for the overhead athlete. The kinetic chain concept will then be applied to clinical exercise modifications and integrations for prevention and treatment of shoulder injury.

RECENT FINDINGS

The primary conclusion reached through this review is the important role the lower extremity, trunk, and scapular region play in the development of optimal terminal segment acceleration in the overhead throwing and serving motion. Failure of any links in the kinetic chain has implications for shoulder and elbow injury in the overhead athlete. Modifications of traditional shoulder exercises emphasizing activation of the scapular stabilizers and core musculature alongside concomitant rotator cuff activation are recommended and supported in EMG research. Future research is needed to further identify risk factors and rehabilitation and prevention strategies and key clinical tests for the overhead athlete. The goal is to elucidate the important role the kinetic chain plays in both performance enhancement and injury prevention for the overhead athlete. Understanding the key role all segments of the kinetic chain play in the complex biomechanical segmental rotations required for high-level throwing and serving will assist clinicians who work with overhead athletes.

Influence of Strength, Power, and Muscular Stiffness on Stroke Velocity in Junior Tennis Players

Objective

The main aim of this study was to establish the relationship between strength, power characteristics, individual muscle stiffness, international tennis number (ITN), and stroke velocity (StV) in junior tennis players.

Methods

Twenty one junior male tennis players (mean ± SD; age, 17.0 ± 0.8 years; height, 1.8 ± 0.1 m; body mass, 72.3 ± 5.8 kg; BMI 22.1 ± 1.5 kg/m²), with an ITN ranging from 2 to 4, performed measurements regarding muscle stiffness of selected muscles involved in tennis strokes. StV (serve, forehand, and backhand), strength (maximum isometric strength) and power (medicine ball throws, squat jump, countermovement jump, and bench press) measurements were also performed (ICC = 0.803–0.998; CV = 0.3–6.4).

Results

Moderate inverse correlations were found between serve velocity (SV) and ITN (r = −0.43; p = 0.05), and large positive correlations were observed between pectoralis majoris stiffness (PMStiff) (r = 0.53; p = 0.01), isometric wrist flexion (r = 0.58; p = 0.006) and ITN, respectively. PMStiff was moderately inversely correlated to forehand velocity (FV) (r = −0.45; p = 0.03) and gastrocnemius (GStiff) and infraspinatus stiffness (IStiff) positively to SV (r = 0.45; p = 0.04; r = 0.42; p = 0.05). No significant correlations were found regarding strength and power measurements.

Conclusion

Greater stiffness values may enhance StV, especially when transferring power from lower to upper body. On the other hand, high scores could interfere in technical parameters that are key for velocity production in complex tennis strokes. Strength and power values proved to correlate poorly to StV in this particular sample of junior tennis players, possibly due to the multifactorial nature of tennis strokes and the possibility that they become more important as age and level increase.

Effects of task and environmental constraints on axial kinematic synergies during the tennis service in expert players

The aims of this study were to examine the effects of task and environmental constraints on axial synergies and to find an association between synergies and arm acceleration as a performance variable. Participants of this study were 10 expert tennis players (age: 34.4 ± 7.46) who voluntarily took part and executed 60 serves under two different conditions: no-opponent and opponent. An inertial motion unit (IMU) capture system was used to calculate the 3D angular joint motions in the neck, back and lumbar segments. The results of the principal component analysis showed that the redundancy in the axial segments is decomposed into 2 main synergies that are responsible for the loading (backward swing) and firing phase (forward swing). The total variance and loading synergy variance were significantly lower in the topspin service than other service types. The emerged firing synergy was strongly associated with the arm acceleration regardless of service type. In conclusion, the effective strategy to utilise the axial motions in the trunk is through creating functional synergies that have a flexible role based on the type of service and conditions. The topspin service showed less coordination variability relative to other types of service and serving in the opponent condition required participants to change the nature of synergy among the axial segments. These findings support the design of practice that emphasises the importance of more realistic contexts with special attention given to the order of different service types.

Hand-Arm Vibration Assessment and Changes in the Thermal Map of the Skin in Tennis Athletes during the Service

During recent years the number of tennis athletes has increased significantly. When playing tennis, the human body is exposed to many situations which can lead to human injuries, such as the so-called tennis elbow (lateral epicondylitis). In this work a biomechanical analysis of tennis athletes, particularly during the service, was performed, considering three different types of over-grip and the presence of one anti-vibrator device. One part of the study evaluates the exposure to hand-arm vibration of the athlete, based on the European Directive 2002/44/EC concerning the minimum health and safety requirements, regarding the exposure of workers to risks from physical agents. The second part of the study considers an infrared thermography analysis in order to identify signs of risk of injury, particularly tennis elbow, one of the most common injuries in this sport. The results show that the presence of the anti-vibrator influences the vibration values greatly in the case of athletes with more experience and also for athletes with less performance. The presence of the Cork and/or Tourna on the racket grip does not have any significant effect on the hand-arm vibration (HAV), similarly in the case of athletes with the best performance and athletes with less technique. The results indicated that the infrared thermography technique may be used to identify the risk of injuries in tennis players.

Lower Trapezius Weakness and Shoulder Complex Biomechanics during the Tennis Serve

PURPOSE

This study aimed to assess the effect of lower trapezius (LT) weakness on humeral and scapular kinematics and shoulder muscle activity during the tennis serve.

METHODS

Fifteen competitive male tennis players (age, 23.8 ± 3.4 yr; height, 182.8 ± 6.7 cm; mass: 76.6 ± 8.7 kg; tennis experience: 15.6 ± 4.9 yr) performed two tennis serves before and after selective fatigue of the LT (25-min electric muscle stimulation). During each tennis serve, racket, humeral and scapular kinematics and the activity of 13 shoulder muscles were recorded using an optoelectronic system synchronized with indwelling and surface electromyography. The serve was split into five phases, that is, early and late cocking, acceleration, early and late follow-through.

RESULTS

Selective fatigue led to a 22.5% ± 10.4% strength decrease but did not alter maximum racket speed and humerothoracic joint kinematics. However, increased scapular upward rotation was observed in the acceleration (P = 0.02) and early follow-through (P = 0.01) phases. Decreased muscular activity was observed during the early cocking phase for the LT (P = 0.01), during the acceleration phase for the LT (P = 0.01), anterior deltoid (P = 0.03), pectoralis major (P = 0.04), and subscapularis (P = 0.03), and during the early follow-through phase for the anterior deltoid (P = 0.03) and LT (P = 0.04).

CONCLUSIONS

The LT weakness altered neither serve velocity nor humerothoracic joint kinematics, but impaired scapulothoracic kinematics and anterior shoulder muscle activation. Such alterations may reduce the subacromial space and jeopardize humeral head stability. These findings shed new light on the consequences of LT weakness, highlighting the importance of monitoring and strengthening this muscle in overhead athletes.

Isokinetic strength training of kinetic chain exercises of a professional tennis player with a minor partial internal abdominal oblique muscle tear - A case report

OBJECTIVE

To present a case of a right-handed professional tennis player with a left internal abdominal oblique muscle tear sustained while serving. We document the progress of a rehabilitation program consisting of primarily kinetic chain isokinetic strength training where symmetrical measurements (<10% side difference) of force and dynamic postural control were used as criteria for return to sport.

METHODS

Isokinetic exercises (bilateral rotational pull, unilateral vertical press and unilateral anterior push) to target trunk specific demands of the serve (flexion, rotation and lateral flexion) were done using robotic resistance. Dynamic postural control was assessed using the hand reach star excursion balance test (HSEBT). The rehabilitation program lasted 3.5 weeks (eight sessions).

RESULTS

At baseline isokinetic strength tests that imposed concentric muscle function demands of the injured muscle had lower force measurements (range: -32.1 to -71.9%). These force measurements improved (range: 166.1-296.5%) and were symmetrical (range: +1.6 to +7.3%) on return to sport. In addition, the HSEBT test with the greatest asymmetry (-20 cm) improved to symmetrical (+2 cm) on return to sport.

CONCLUSION

Symmetrical isokinetic force and dynamic postural control measurements were successful return to sport criteria as the player since has remained pain free (2 years).

Inter-Session Reliability of the Tennis Serve and Influence of the Laboratory Context

To meet the demand of a player’s entourage (e.g., coaches and medical staff), it is important for the biomechanics specialist to perform repeatable measures. To the best of our knowledge, to date, it has not been demonstrated whether similar results are obtained between two sessions of testing or between laboratory and field sport kinematic protocols with regard to the tennis serve. This study had two primary aims. First, the inter-session repeatability of biomechanical variables of a tennis serve was evaluated. Second, the differences between laboratory and field evaluations were studied. Thirteen national tennis players (ITN 3) performed the same 28 markers’ set laboratory test twice two weeks apart, and other thirteen national players (ITN 3) performed two 4 markers’ set tests both in the laboratory and on an official tennis court one week apart. A 3D motion system was used to measure lower-limb, pelvis, trunk, dominant arm and racket kinematics. A force plate was used to evaluate kinetics of legs’ drive in the laboratory. A personal method based on a point scoring system was developed to evaluate the ball landing location accuracy. We observed that the majority of the studied variables were acceptable for excellent relative reliability for the inter-session analysis. We also showed that the impact of the laboratory versus field context on the player’s serve was limited

Evolution of the trophy position along the tennis serve player's development

The trophy position is a coaching cue for the tennis serve that usually corresponds to the racquet high point (RHP) during the preparatory action for the stroke. Mastering this position and its time of occurrence seems essential in overarm movements like in the tennis serve. Clinicians and coaches have a real interest in understanding the trophy position and its evolution during the development of the elite players at different ages. A 3D motion system was used to measure the kinematics of the serve. A group of high-level tennis players were selected for three different age groups: 8 adults (ITN 1), 8 teenagers (ITN 3) and 8 children (ITN 5-6). Results show a modified pattern sequence of the tennis serve between children and adult players. RHP appears earlier relative to impact for children (-0.54 ± 0.10 s) than for adults (-0.36 ± 0.11 s) and teenagers (-0.33 ± 0.05 s) (p = 0.007). At RHP, children present lower trunk transverse plane rotation (p < 0.003) and higher shoulder external rotation (p < 0.003). These positions for the child players may represent an increased risk of shoulder and trunk injury than for older players and contribute to a lower racquet resultant velocity at impact.

Biomechanical analysis of the "waiter's serve" on upper limb loads in young elite tennis players

Waiter's serve (WS) is a specific tennis serve posture frequently observed in young players, and commonly considered as a technical error by tennis coaches. However, biomechanical impact of WS is unknown. The aims of this study were to identify the potential consequences of WS in young elite players relating to performance and injury risk, and to explain the kinematic causes of WS. Serve of 18 male junior elite players (Top 10 national French ranking, aged 12-15 years) was captured with a 20 camera, 200 Hz VICON MX motion analysis system. Depending on their serve technique, the players were divided into two groups (WS versus Normal Serve [NS]) by experienced coaches. Injury data were collected for each player during a 12-month-period following the motion capture. Normalized peak kinetic values of the dominant arm were calculated using inverse dynamics. In order to explain WS posture, upper limb kinematics were calculated during the cocking and the acceleration phases of the serve. Shoulder internal rotation torque, wrist proximal and anterior forces (P < .05) and elbow varus torque (P < .01) were significantly higher in WS group, with no difference from NS group concerning serve velocity. Moreover, significant lower shoulder abduction and higher wrist extension (P < .05) were observed for WS players during the cocking phase. Even if no significant difference was found between groups concerning injuries, higher upper limb joint loads suggested WS could be considered as pathomechanical in young elite players and could lead to upper limb joint injuries.

Alterations in scapulothoracic and humerothoracic kinematics during the tennis serve in adolescent players with a history of shoulder problems

The tennis serve generates high musculoskeletal loads at the shoulder complex, making athletes particularly vulnerable to chronic injuries, especially adolescent players. Chronic injuries are commonly related to altered scapular kinematics. This study explored the effects of a history of shoulder problems involving humerothoracic and scapulothoracic kinematics during the tennis serve at low speed in adolescent competitive players with and without a history of dominant shoulder problems. Totally, 28 adolescent tennis players were split into two groups, those with and those without a history of shoulder problems. Data on humeral and scapular kinematics relative to the thorax were collected using an electromagnetic system during slow velocity serves. The two groups's humerothoracic and scapulothoracic 3D joint angles were compared both at the end of the cocking phase and at the end of the acceleration phase of the tennis serve. At the end of the cocking phase, the players with a 30 history of shoulder problems showed less humeral abduction and external rotation and more scapular upward rotation. This group also showed less humeral abduction at the end of the acceleration phase. Players with a history of shoulder problems adapted their humerothoracic and scapulothoracic orientations to preserve shoulder integrity during the tennis serve.

Effect of environmental constraints on multi-segment coordination patterns during the tennis service in expert performers

The aims of this study were to examine the effect of different environmental constraints on kinematic multi-segment coordination patterns during the service and its coordination with service time variability. Ten expert tennis players (Age: 34.1 ± 5.3) volunteered to take part in this study. Participants served 30 times in 3 different conditions: control, target and opposition. The order of conditions was counterbalanced between participants. A wireless 3D motion capture system (STT Co, Spain) was used to measure 7 joint motions, with a 17 degrees of freedom biomechanical model created to capture the entire service action. Results of the principal component analysis showed that 4 synergies were created; however, their roles were changed relative to the perception of the environment. The results of repeated-measures analysis of variance did not show any significant difference on total variance and individual principal components between conditions; however, one synergy pattern significantly predicted the service time variability in both control and opposition conditions. In conclusion, the findings demonstrated that expert performers reduce the joint dimensionality by creating functional synergies in different phases of service and adapt the service action according to the perception of the environment.

Relationship Between Range of Motion, Strength, Motor Control, Power, and the Tennis Serve in Competitive-Level Tennis Players: A Pilot Study

BACKGROUND

The tennis serve is a complex skill requiring appropriate energy transfer to maximize serve speed. As the only independently powered shot in tennis, it is important to understand what characteristics contribute to a player's serve.

HYPOTHESIS

Upper extremity and lower extremity power variables will be predictive of serve speed.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 42 competitive tennis players underwent range of motion, strength, motor control, power, and serve speed testing. Motion assessment was completed for shoulder external and internal rotation, trunk rotation, hip external and internal rotation, and ankle dorsiflexion. Strength was assessed for the rotator cuff, scapula, and hip musculature. Motor control was evaluated through upper and lower extremity Y-balance testing. Power assessments were made using broad jump, single-leg hop, and seated unilateral shot put testing. Pearson correlation was conducted to assess associations of skill, height, and tested variables to serve speed. Significant variables were used in a stepwise linear regression model, with serve speed as the dependent variable. Variables are listed in relation to the participant's dominant arm.

RESULTS

Skill, height, contralateral hip external rotation range of motion, nondominant arm Y-balance anterolateral reach, bilateral single-leg hops, and seated unilateral shot put throws for both arms demonstrated significant positive correlations to serve speed ( P < 0.05). Serve speed was predicted with 84% variance through skill, height, contralateral hip external rotation range of motion, ipsilateral single-leg hop, and the seated unilateral shot put throws.

CONCLUSION

The ability to generate increased serve speed is multifactorial. The combination of skill, height, hip motion, and upper and lower extremity power may determine serve speed.

CLINICAL RELEVANCE

The findings suggest that motion, motor control, and power testing should be evaluated when working with this population to improve serve speed.

Validation of a Tennis Rating Score to evaluate the technical level of children tennis players

The purpose of this study was to create a valid and reliable assessment scale for the evaluation of three basic tennis strokes (forehand, backhand, serve) for 6-12-year-old tennis players, named the Tennis Rating Score for Children (TRSC). Altogether 60 players (21: forehand, 22: backhand, 17: serve) were video recorded (30 frames per second) while performing three main tennis strokes and later evaluated using the TRSC by five tennis trainers at Day 1 and Day 7. Agreement between days and raters was examined using the intraclass correlation coefficients (ICC). A Pearson's correlation was calculated to determine convergent validity (score related to participant's level of experience). The reliability between raters was very high for all three main strokes (ICC_FOREHAND = 0.874; ICC_BACKHAND = 0.877; ICC_SERVE = 0.877). The intra-rater test-retests ICCs were also very high (ICC_FOREHAND = 0.885; ICC_BACKHAND = 0.891; ICC_SERVE = 0.887). A large (r_FOREHAND = 0.660) and very large (r_BACKHAND = 0.730; r_SERVE = 0.772) Pearson's correlations were found between all the ratings and the level of experience. The TRSC is shown to be highly reliable and valid when assessing technical skills in novice players, when compared to actual assessment from coaching experts; this tool may be helpful for tennis coaches to make a more objective diagnostic of the technical level of young tennis players.

Comparing the biomechanical characteristics between squat and standing serves in female table tennis athletes

Background

The table tennis serve involves complex spatial movements combined with biomechanial characteristics. Although the differences in lower-limb biomechanial characteristics to a great extent influence the translational and spinning velocity of the ball when using the different styles of table tennis serve, few researchers have studied their mechanics. Therefore, the aim of this study was to investigate the differences in lower-limb activity between the squat and standing serves during a table tennis short serve.

Methods

Ten advanced female table tennis participants performed a squat serve and standing serve in random order. A Vicon motion analysis system and a Novel Pedar insole plantar pressure measurement system were used to record kinematics and kinetics data, respectively.

Results

Key findings from the study were that the squat serve not only showed significantly larger hip and knee flexion, as well as ankle dorsiflexion, it also showed significantly larger hip adduction and external knee rotation, with larger changing angular rate of the lower limb joints in the sagittal and the transverse planes when the two serving styles were compared. In addition, the force-time integral (FTI) was higher in the rear foot area for the standing serve.

Discussion

The results demonstrated that the squat serve needs higher lower limb drive during a table tennis short serve compared with a standing serve. These biomechanical considerations may be beneficial for table tennis athletes and coaches as a method of optimizing performance characteristics during both competition and training.

Epidemiology of injuries in tennis players

PURPOSE OF REVIEW

To review the recent literature regarding the epidemiology of tennis injuries at all levels of play, and to discuss recent findings in injury surveillance by the Association of Tennis Professionals (ATP).

RECENT FINDINGS

Following the release of a consensus statement in 2009 calling for standardized documentation and analysis of tennis-related injuries, multiple studies have been published describing longitudinal injury incidences at Grand Slam tournaments and the Davis Cup. Recent efforts by the ATP have further elucidated injury patterns on tour. There have also been recent high-quality studies on injury trends among collegiate and elite junior tennis players, bringing attention to musculoskeletal injuries and systemic illnesses that young tennis players may be susceptible to. Recent efforts in injury surveillance by the ATP and at the collegiate and junior levels have highlighted injury trends that will help guide injury prevention strategies at various levels of play.

A COMPARATIVE STUDY OF PASSIVE SHOULDER ROTATION RANGE OF MOTION, ISOMETRIC ROTATION STRENGTH AND SERVE SPEED BETWEEN ELITE TENNIS PLAYERS WITH AND WITHOUT HISTORY OF SHOULDER PAIN

BACKGROUND

Glenohumeral internal rotation deficit and external rotation strength have been associated with the development of shoulder pain in overhead athletes.

OBJECTIVE

To examine the bilateral passive shoulder rotational range of motion (ROM), the isometric rotational strength and unilateral serve speed in elite tennis players with and without shoulder pain history (PH and NPH, respectively) and compare between dominant and non-dominant limbs and between groups.

STUDY DESIGN

Cohort study.

METHODS

Fifty-eight elite tennis players were distributed into the PH group (n = 20) and the NPH group (n = 38). Serve velocity, dominant and non-dominant passive shoulder external and internal rotation (ER and IR) ROM, total arc of motion (TAM: the sum of IR and ER ROM), ER and IR isometric strength, bilateral deficits and ER/IR strength ratio were measured in both groups. Questionnaires were administered in order to classify characteristics of shoulder pain.

RESULTS

The dominant shoulder showed significantly reduced IR ROM and TAM, and increased ER ROM compared to the non-dominant shoulder in both groups. Isometric ER strength and ER/IR strength ratio were significantly lower in the dominant shoulder in the PH group when compared with the NPH group. No significant differences between groups were found for serve speed.

CONCLUSION

These data show specific adaptations in the IR, TAM and ER ROM in the dominant shoulder in both groups. Isometric ER muscle weakness and ER/IR strength ratio deficit appear to be associated with history of shoulder injuries in elite tennis players. It would be advisable for clinicians to use the present information to design injury prevention programs.

LEVEL OF EVIDENCE

2.

Sequence-dependent rotation axis changes in tennis

The purpose of this study was to evaluate the role of rotation axes during a tennis serve. A motion capture system was used to evaluate the contribution of the potential axes of rotation (minimum inertia axis, shoulder-centre of mass axis and the shoulder-elbow axis) during the four discrete tennis serve phases (loading, cocking, acceleration and follow through). Ten ranked athletes (International Tennis Number 1-3) repeatedly performed a flat service aiming at a target on the other side of the net. The four serve phases are distinct and thus, each movement phase seems to be organised around specific rotation axes. The results showed that the limbs' rotational axis does not necessarily coincide with the minimum inertia axis across the cocking phase of the tennis serve. Even though individual serving strategies were exposed, all participants showed an effect due to the cocking phase and changed the rotation axis during the task. Taken together, the results showed that despite inter-individual differences, nine out of 10 participants changed the rotation axis towards the minimum inertia and/or the mass axis in an endeavour to maximise external rotation of the shoulder to optimally prepare for the acceleration phase.