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.

Effects of Maturation on Lower-Body Neuromuscular Performance in Youth Tennis Players.

ABSTRACT: Fernandez-Fernandez, J, Canós-Portalés, J, Martinez-Gallego, R, Corbi, F, and Baiget, E. Effects of maturation on lower body neuromuscular performance in youth tennis players. J Strength Cond Res 37(1): 167-173, 2023-The aim of this study was to examine the maturational status differences in neuromuscular performance of young tennis players. One hundred fifty-five junior tennis players (91 boys and 64 girls; age 13.1 ± 2.2 years, body mass 50.0 ± 12.2 kg, height 159.7 ± 12.4 cm, and estimated age at peak height velocity [PHV] 12.7 ± 1.6 years) participated in the study and were divided into pre-PHV (n = 57), circa-PHV (n = 50), and post-PHV (n = 48) groups. Physical tests included speed (5, 10, and 20 m), modified 5-0-5 change of direction (COD) test, hexagon test, and bilateral or unilateral countermovement jump (CMJ). The main results showed that compared with the post-PHV, pre-PHV players presented lower levels of performance in CMJs (p < 0.001; effect size [ES]: 0.76-0.88), linear sprints, and COD ability tests (p < 0.001; ES: 1.4-1.5). In addition, compared with circa-PHV, pre-PHV players also demonstrated lower performance levels in both linear sprints (p < 0.001; ES: 0.93-1.12) and COD abilities (p < 0.01; ES: 0.58-0.94). On the contrary, COD deficit (CODDEF) was significantly lower in the pre-PHV group than the circa-PHV (p < 0.001; ES: 0.76-0.79) and post-PHV (p < 0.001; ES: 1.04-1.05) groups. These results highlight the need to use the maturity stage (i.e., PHV) instead of chronological age as a more appropriate parameter when designing training programs. Furthermore, based on the differences found between groups, specific training strategies, such as neuromuscular training and COD workouts, related to the different maturation stages should be recommended.

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.

Effects of different maturity status on change of direction performance of youth tennis players.

The aim of this study was to examine the maturational status (i.e., peak height velocity [PHV]) differences in neuromuscular performance (i.e., vertical jump, linear sprint, change of direction (COD) using different tests, and change of direction deficit [CODD]) of young tennis players. One hundred and two tennis players (70 boys and 52 girls; age 13.9 ± 2.0 years, body mass 53.3 ± 12.7 kg, height 163.1 ± 11.9 cm) participated in the study and were divided into Pre-PHV (n = 26), Circa-PHV (n = 33) and Post-PHV (n = 43) groups. Testing included speed (5, 10, and 20 m), COD tests (i.e., modified 5-0-5, pro-agility and hexagon), and bilateral/unilateral countermovement jump (CMJ). Pre- and Circa-PHV players presented lower levels of performance in jumping ability (i.e., both bilateral and unilateral CMJs; P < 0.001; ES: 0.85 to 0.98), linear sprints (5 to 20 m; P < 0.05 to < 0.001; ES: 0.67 to 1.19) and COD ability tests (modified 5-0-5 test, pro-agility and hexagon) compared to the Post-PHV players. Moreover, Pre-PHV players presented lower CODD% (p < 0.05; ES: 0.68-0.72) than Post-PHV for both forehand and backhand sides, and Circa-PHV showed lower values in the CODD of the rolling situation to the forehand side (p < 0.05; ES: 0.58). Among the COD tests, the pro-agility test seems to be a simple, easy-to-implement and reliable test, which can provide interesting information about the COD with higher entry speeds. Moreover, specific training strategies related to the PHV and focused not only on the neuromuscular training and COD workouts, but also on maximizing motor skill proficiency, should be recommended.

Effects of isoinertial or machine-based strength training on performance in tennis players.

The objective of this study was to analyze the effects of two 8-week neuromuscular training (NMT) interventions on selected physical indicators in young tennis players. Twenty-four junior male tennis players were assigned to a machine-based (MG) (n = 8), flywheel (FG) (n = 8) or a control training group (CG) (n = 8). Tests at baseline, week 4 and 8 included: countermovement jump (CMJ); speed (S; 5, 10, 15 m); agility (right [AR] and left [AL]); serve velocity (SV) and medicine ball throws (MBT; overhead [O], forehand [FH], backhand [BH]). MG and FG attained large positive effects at week 4 in CMJ, S 10 m; AR, AL and MBT FH only in FG. Regarding inter- to post-test, MG achieved large positive effects in MBT O, FH and both groups in BH. Large negative effects appeared for FG in S 5 and 10 m and AR and AL. Both NMT interventions led to positive effects from baseline to week 4 measures in CMJ, S 5 m, 10 m and agility and at week 8 in MBT. Conducting the same NMT for a longer period of time did not lead to the same improvements and other negative effects in FG appeared. Results indicate that performing these interventions with little exercise variability or load management, especially after technical-tactical sessions, could interpose further beneficial outcomes and initial gains could be impaired.

Force-Time Curve Variable Outcomes Following a Simulated Tennis Match in Junior Players.

This study examined the alterations induced by a simulated tennis competition on maximal isometric voluntary contraction (MVC), peak rate of force development (PRFD) and rate of force development (RFD) at different stages of contraction. Twenty junior tennis players performed an 80-minute simulated tennis match and two (pre and post) muscular performance tests. Variables tested included MVC, PRFD and RFD at 50, 100, 150 and 200 ms while performing a 90º shoulder internal rotation (IR90), 90º shoulder external rotation (ER90), shoulder horizontal adduction (ADD), shoulder horizontal abduction (ABD) and isometric mid-thigh pull (IMTP). Serve velocity (SV) was also registered. No significant changes were found regarding MVC, PRFD or SV. Non-significant moderate effect size (ES) towards a decrease in the IR90 RFD at 50 ms could be observed (16%; ES = 0.5) alongside an increase in the ADD and IMTP RFD at 150 ms (-15.8%, -8.2%; ES = -0.53, -0.54) and IMTP RFD at 200 ms (-13%; ES = -0.54). Results indicate that MVC, PRFD, RFD at different time intervals and SV are unaltered following an 80-minute simulated match, possibly due to insufficient alterations triggered on key factors affecting the tested variables.

Validity of Heart Rate-Based Models for Estimating Oxygen Uptake During Tennis Play.

Baiget, E, Iglesias, X, and Rodríguez, FA. Validity of heart rate-based models for estimating oxygen uptake during tennis play. J Strength Cond Res 34(11): 3208-3216, 2020-This study aimed to assess the validity of an on-court tennis test (specific endurance tennis test [SET-Test]) and 2 heart rate (HR)-based methods for estimating oxygen uptake (V[Combining Dot Above]O2) in competitive tennis players. Thirty-five male players performed a SET-Test to relate test duration (minutes) and V[Combining Dot Above]O2. Two weeks later, 16 players performed a simulated match play set where HR and V[Combining Dot Above]O2 (V[Combining Dot Above]O2-PLAY, criterion value) were measured and then compared with V[Combining Dot Above]O2 values predicted from the HR/V[Combining Dot Above]O2 linear regression equations derived from the SET-Test (pV[Combining Dot Above]O2-TEST) and from the one set match play (pV[Combining Dot Above]O2-PLAY). Test duration and V[Combining Dot Above]O2-TEST were strongly correlated (r = 0.821, p < 0.001, SEE = 5.6 ml·kg·min), indicating that SET-Test outcome is a somewhat good indicator of aerobic fitness in tennis players, likely to be useful for training purposes. pV[Combining Dot Above]O2-PLAY and V[Combining Dot Above]O2-PLAY (criterion value) were strongly correlated (r = 0.832, p < 0.001) and SEE was moderate (3.5 ml·kg·min = 11.5%). pV[Combining Dot Above]O2-TEST differed from the criterion (32.4 ± 10.7 vs. 30.8 ± 8.6 ml·kg·min, p < 0.001) and, although strongly correlated (r = 0.689, p < 0.001), an overestimation occurred (mean Δ = 1.6 ml·kg·min = 4.9%), yielding a high SEE (4.8 ml·kg·min = 15.6%). We conclude that (a) SET-Test performance is a valid and moderately accurate predictor of V[Combining Dot Above]O2; and (b) the individual HR-V[Combining Dot Above]O2 regression equation generated during tennis match play predicts V[Combining Dot Above]O2 with greater accuracy than the regression derived from the SET-Test.

Maximal Aerobic Frequency of Ball Hitting: A New Training Load Parameter in Tennis.

Baiget, E, Iglesias, X, and Rodríguez, FA. Maximal aerobic frequency of ball hitting: a new training load parameter in tennis. J Strength Cond Res 31(1): 106-114, 2017-This study aimed (a) to evaluate a new training load parameter in tennis based on the ball-hitting frequency (Ballf) at V[Combining Dot Above]O2max occurs (maximal aerobic frequency of ball hitting, MAF) and (b) to assess the accuracy of a specific endurance tennis test (SET-Test) for predicting MAF. Thirty-five male competitive tennis players performed the SET-Test and selected physiological and performance parameters at maximal workload (MAX), and last completed stage (LS) and MAF were compared. Performance parameters (Ballf, time, stage, and hits per test) at LS were higher than at MAF (20.2 ± 1.7 vs. 18.1 ± 1.5 shots·min, 6.6 ± 0.8 vs. 5.6 ± 0.8 stages, and 189 ± 33 vs. 147 ± 27 hits; p < 0.001), and highly correlated (r = 0.72-0.77; p < 0.001). The mean difference between Ballf and stage at MAF and LS were 2.1 ± 1.1 shots·min and 1.1 ± 0.6 stages, respectively. The main physiological parameters (heart rate, V[Combining Dot Above]O2, and V[Combining Dot Above]CO2 at LS) were higher than at MAF (191 ± 9 vs. 186 ± 8 beats·min, 55.5 ± 5.9 vs. 55.0 ± 6.0 ml·kg·min and 4,724 ± 880 vs. 4,253 ± 739 ml·min; p < 0.005), and were very strongly correlated (r = 0.93-0.99; p < 0.001). We conclude that MAF can be used as a practical performance parameter to prescribe tennis-specific training, and that the SET-Test is a valid method for assessing MAF. Gas exchange measurements not being available, as a rule of thumb, most players reach their MAF at ∼1 stage (95% confidence interval: 0.9-1.2) and ∼2 shots·min (95% confidence interval: 1.7-2.5) less than their completed LS. A model for specific on-court training protocols for optimizing aerobic fitness in competitive tennis player is proposed.

Heart rate deflection point relates to second ventilatory threshold in a tennis test.

The relationship between heart rate deflection point (HRDP) and the second ventilatory threshold (VT2) has been studied in continuous sports, but never in a tennis-specific test. The aim of the study was to assess the relationships between HRDP and the VT2, and between the maximal test performance and the maximal oxygen uptake ((Equation is included in full-text article.)) in an on-court specific endurance tennis test. Thirty-five high-level tennis players performed a progressive tennis-specific field test to exhaustion to determine HRDP, VT2, and (Equation is included in full-text article.). Ventilatory gas exchange parameters were continuously recorded by a portable telemetric breath-by-breath gas exchange measurement system. Heart rate deflection point was identified at the point at which the slope values of the linear portion of the time/heart rate (HR) relationship began to decline and was successfully determined in 91.4% of the players. High correlations (r = 0.79-0.96; p < 0.001) between physiological (HR and oxygen uptake [(Equation is included in full-text article.)]) and performance (Time, Stage, and Frequency of balls [Ballf]) variables corresponding to HRDP and VT2 were observed. Frequency of balls at the HRDP (BallfHRDP) was detected at 19.8 ± 1.7 shots per minute. Paired t-test showed no significant differences in HR (178.9 ± 8.5 vs. 177.9 ± 8.7 b·min for HRDP vs. HRVT2, respectively) at intensities corresponding to HRDP and VT2. Maximal test performance and (Equation is included in full-text article.)were moderately correlated (r = 0.56; p < 0.001). Heart rate deflection point obtained from this specific tennis test can be used to determine the VT2, and the BallfHRDP can be used as a practical performance variable to prescribe on-court specific aerobic training at or near VT2.

On-court endurance and performance testing in competitive male tennis players.

The aims of this study were (a) to establish a specific endurance test procedure for competitive tennis players, combining performance, physiological and technical parameters and (b) to determine the relationship between these parameters and their competitive levels. Thirty-eight competitive male tennis players (age, 18.2 ± 1.3 years; height, 180 ± 0.08 cm; body mass, 72.7 ± 8.6 kg; mean ± SD) performed a specific endurance field test. Performance (level achieved), physiological (heart rate, maximum oxygen uptake (VO2max), and ventilatory thresholds (VT1, VT2), and technical parameters (technical effectiveness [TE]) were assessed. Bivariate and multivariate models for predicting performance level were developed. Technical effectiveness was 63.1 ± 9.1%, with 3 identified phases throughout the test (adaptation, maximum effectiveness, and steady decline). Low to moderate correlations were found between performance (final stage), physiological (VT1, VT2) and TE, and competitive performance (r = 0.35-0.61; p = 0.038-0.000). Technical effectiveness explained 37% of variability in competitive performance (r = 0.61; p = 0.001). Using TE combined with VT2 or predictability increased explaining approximately 55% (p < 0.05) of the variance in competitive performance. The present study showed the usefulness of a field test including physiological and performance elements in high-caliber tennis players, and VT2 values combined with TE were good predictors of tennis performance.

Comparison of the finishing shot and ending zone of points in Grand Slam matches of women's doubles tennis: A cross-sectional study.

Despite the importance of doubles tennis, there is little research on this modality of the game, especially in women's tennis. The aim of this study was to analyse the finishing shot, the ending zone and shot by ending zone of women´s doubles matches during three Grand Slams (GS), and to observe the differences among surfaces. Twenty-one women's doubles matches from three GS, each played on a different surface were analysed. 56.4 ± 2.3% of the points were finished from the baseline and mid court zone (BMZ), 36.1 ± 2.3% from the net zone (NZ) and 7.5 ± 4.2% from the service zone (SZ). The shot with which the points ended primarily was the forehand volley (FV) (18.2 ± 3.5%), followed by the forehand (F) (17.4 ± 4.2%), the backhand (B) (15.8 ± 4.8%), the backhand volley (BV) (12.8 ± 3.6%), the forehand return (FRT) (11.7 ± 2.7%), the backhand return (BRT) (11.4 ± 2.6%), the service (S) (7.5 ± 4.2%) and the overhead (O) (5.2 ± 3.0%). The results showed a higher percentage of F played from the BMZ in Roland Garros (RG) than in Wimbledon (W) (p = 0.011). In addition, the results also showed a higher percentage in overall F in RG than in W (p = 0.023). The FRT percentage was higher in the Australian Open (AUS) compared to RG (p = 0.026), and the O shots played from the BMZ were higher in W than RG (p = 0.038). These results suggest that in professional women's doubles tennis the net game is a determinant factor, as well as the volley (V) and F shots. Playing aggressive and close to the net may have a positive effect on the result.

Retirements of professional tennis players in second- and third-tier tournaments on the ATP and WTA tours.

The demands of professional tennis, including physical and psychological aspects, contribute to the frequency of retirements at elite levels of the sport. The aim of this study was to analyze epidemiological patterns and risk factors associated with retirements in previous ATP and WTA Tour tournaments. A retrospective cohort study was conducted. This study focused on previous ATP and WTA Tour tournaments. The ATP database encompassed 584,806 matches, while the WTA database included 267,380 matches. To assess retirements, potential risk factors such as playing surface, tournament category, match round, and player age were analyzed. Incidence rates were calculated for the period between 1978-2019 for men and 1994-2018 for women. The overall incidence rate was 1.56 (95%CI: 1.54, 1.59) and 1.36 (95%CI: 1.33, 1.39) retirements per 1000 games played in male and female competitions, respectively. Retirements increased over the years. Higher incidence rates were observed on hard (1.59 [95%CI: 1.56, 1.63] and 1.39 [95%CI: 1.34, 1.44]) and clay (1.60 [95%CI: 1.57, 1.63] and 1.36 [95%CI: 1.32, 1.41]) compared to grass courts (0.79 [95%CI: 0.65, 0.94] and 1.06 [95%CI: 0.88, 1.27]). Risk factors differed by gender, with tournament category significant in males (IRR: 1.23 [95%CI: 1.19, 1.28] in ITF vs ATP) and match round in females (IRR: 0.92 [95%CI: 0.88, 0.98] in preliminary vs final). This study provides valuable insights for coaches, players, support teams, and epidemiologists regarding retirements and associated risk factors in previous ATP and WTA Tour tournaments, contributing to injury prevention strategies.

Quantifying Hitting Load in Racket Sports: A Scoping Review of Key Technologies.

PURPOSE: This scoping review aims to identify the primary racket and arm-mounted technologies based on inertial measurement units that enable the quantification of hitting load in racket sports. METHODS: A comprehensive search of several databases (PubMed, SPORTDiscus, Web of Science, and IEEE Xplore) and Google search engines was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) extension for scoping reviews guidelines. Included records primarily focused on monitoring hitting load in racket sports using commercialized racket or arm-mounted inertial sensors through noncompetitive and competitive racket-sports players. RESULTS: A total of 484 records were identified, and 19 finally met the inclusion criteria. The largest number of systems found were compatible with tennis (n = 11), followed by badminton (n = 4), table tennis (n = 2), padel (n = 1), and squash (n = 1). Four sensor locations were identified: grip-attached (n = 8), grip-embedded (n = 6), wrist (n = 3), and dampener sensors (n = 2). Among the tennis sensors, only 4 out of the 11 (36.4%) demonstrated excellent reliability (>.85) in monitoring the number of shots hit either during analytic drills or during simulated matches. None of the other racket-sports sensors have undergone successful, reliable validation for hitting-volume quantification. CONCLUSIONS: Despite recent advancements in this field, the quantification of hitting volume in racket sports remains a challenge, with only a limited number of tennis devices demonstrating reliable results. Thus, further progress in technology and research is essential to develop comprehensive solutions that adequately address these specific requirements.

Six-Week Joint-Specific Isometric Strength Training Improves Serve Velocity in Young Tennis Players.

PURPOSE: Evaluate the effects of 6 weeks of specific-joint isometric strength training on serve velocity (SV), serve accuracy (SA), and force-time curve variables. METHODS: Sixteen young competition tennis players were divided into an intervention (n = 10) or control group (n = 6). SV, SA, maximal voluntary isometric contraction, peak rate of force development, rate of force development, and impulse (IMP) at different time frames while performing a shoulder internal rotation (SHIR) or flexion were tested at weeks 0, 3, and 6. RESULTS: The intervention group showed significant increases in SV from pretest to posttest (7.0%, effect size [ES] = 0.87) and no variations in SA. Moreover, the intervention group showed significant increases from pretest to posttest in shoulder-flexion rate of force development at 150 (30.4%, ES = 2.44), 200 (36.5%, ES = 1.26), and 250 ms (43.7%, ES = 1.67) and in SHIR IMP at 150 (35.7%, ES = 1.18), 200 (33.4%, ES = 1.19), and 250 ms (35.6%, ES = 1.08). Furthermore, significant increases were found in shoulder-flexion rate of force development from intertest to posttest at 150 ms (24.5%, ES = 1.07) and in SHIR IMP at 150 (13.5%, ES = 0.90), 200 (19.1%, ES = 0.98), and 250 ms (27.2%, ES = 1.16). SHIR IMP changes from pretest to intertest were found at 150 ms (25.6%, ES = 1.04). The control group did not show changes in any of the tested variables. CONCLUSIONS: Six weeks of upper-limb specific-joint isometric strength training alongside habitual technical-tactical workouts results in significant increases in SV without SA detriment in young tennis players.

Performance Outcomes Following Isoinertial or Machine-Based Training Interventions in Female Junior Tennis Players.

PURPOSE: To evaluate changes in physical performance indicators after executing a flywheel or machine-based neuromuscular training program in young female tennis players. METHODS: Twenty-four players were divided into a machine-based  group (MG), flywheel  group (FG), and control group. Countermovement jump (CMJ), sprint time (5, 10, and 15 m), change-of-direction (COD) performance (right and left), medicine-ball throws (overhead, forehand, and backhand), and serve velocity were included as tests at baseline, week 4, and week 8. RESULTS: Both MG and FG largely improved from baseline to weeks 4 and 8 of training in CMJ (11.6, 10.6%; effect size [ES] = 1.24, 1.95). Also, sprint time 5 m and 10 m, COD performance-right, and COD performance-left improved moderately to very largely at week 4 in MG (-5.0% to -6.2%; ES = -1.79 to -4.19) and FG (-2.9% to -5.1%; ES = -1.13 to -1.64), respectively. Regarding medicine-ball throw, only FG improved moderately to very largely from weeks 4 to 8 in overhead (9.3%; ES = 1.46), forehand (8.0%; ES = 1.08), and backhand (6.1%; ES = 1.15). Serve velocity improved moderately from weeks 4 to 8 in MG (5.8%; ES = 0.87). CONCLUSIONS: Four weeks of the tested programs seem sufficient to improve physical determinants in young female participants. Greater improvements in CMJ and medicine-ball throw following flywheel neuromuscular training indicate the importance of including exercises that emphasize the stretch-shortening cycle and involve the entire kinetic chain. Performing the same intervention with no load adjustments may stall or even decrease performance in some parameters from weeks 4 to 8.

Effects of 4 Weeks of Variability Training on Forehand Approach Precision and Velocity in Recreational Tennis Players.

This study aims to analyze the effects of a training program based on practice variability on the speed and accuracy of the tennis forehand approach to the net shot. The study sample consisted of 35 players of both genders, 22 men and 13 women (age 44 ± 10.9 years, height 1.73 ± 0.8 cm, and weight 74.7 ± 8.4 kg). Players were randomly distributed into two groups (control group = 18 and experimental group = 17). Both training groups worked a total volume of 4 weeks, seven sessions, and 15 min per session of forehand approach shot. Control group performed traditional training while experimental group trained with variability using wristband weights. The data obtained showed a large Group × Time interaction in the accuracy of the forehand approach shot, F(1, 16) = 28.034, p < .001, η2 = .637. Only the experimental group increased significantly in the accuracy after the program (51.4%, effect size = 1.3, p < .001), while no changes were achieved regarding hitting speed (1.2%, effect size = 0.12, p = .62). The control group did not improve in any of the tested variables. These results indicate that variability of training using wrist weights is a valid option to improve forehand approach shot accuracy in recreational-level players. Although stroke speed was not increased, this type of training may be interesting as accuracy and technical control is commonly the main goal of training at this level.

Relationship between isometric force-time curve variables and serve velocity in young tennis players.

This study aimed to investigate the associations between serve velocity (SV), maximal absolute and relative isometric voluntary contraction (MVC and RMVC), peak rate of force development (PRFD), rate of force development (RFD) and impulse (IMP) at different stages of contraction (≤200 ms). Sixteen players performed four maximum isometric tests in positions involved in the tennis serve motion. Variables tested included MVC, PRFD, RFD and IMP at 50, 100, 150 and 200 ms while performing a 90º shoulder internal rotation (SHIR), shoulder flexion (SHF), horizontal shoulder abduction (SHABD) and an isometric mid-thigh pull (IMTP). Significant (p ≤ 0.05) moderate-to-very-large correlations were found between SV, MVC and PRFD. RFD at different time intervals showed positive associations with SV, except in the SHF0-200 ms and IMTP0-200 ms. Accordingly, IMP values positively correlated with SV in all positions except in the SHIR0-50 ms and the IMTP in late contraction stages. Results indicate that the combination of maximum isometric strength in several body positions involved in the serve kinetic chain alongside RFD and IMP in short periods of time (≤200 ms) positively influences SV in young participants.

Inter-Limb Muscle Property Differences in Junior Tennis Players.

The goal of this study was to investigate side-to-side differences and asymmetries regarding muscle characteristics in young tennis players. Thirty-four participants performed contractile property measurements (stiffness, tone, elasticity and time to relaxation) on the dominant and non-dominant extremities including nine muscle groups involved in the kinetic chain of main tennis strokes. Significant differences (p≤0.05) and small-to-moderate effect sizes for greater stiffness and tone were found for the dominant biceps femoris (-11.1% and -5.6%; ES=0.53 and 0.54) and the non-dominant vastus medialis (5.4% and 3.2%; ES=-0.33 and -0.41), while greater tone was present in the non-dominant pectoralis major (4.0%; ES=-0.56). Time to relaxation was increased in the dominant biceps femoris (10.3%; ES=-0.58), the non-dominant pectoralis major (5.1%; ES=-0.56) and the gastrocnemius (9.1%; ES=-0.5). The non-dominant infraspinatus and dominant rectus abdominis showed greater elasticity than contralateral muscles (9.9% and -8.0%; ES=-0.58 and 0.6, respectively). These results reflect the existence of small-to-moderate differences when comparing side-to-side values of contractile characteristics in a small amount of the muscle groups tested. However, passive measurements of a relaxed muscle do not seem to fully reflect possible adaptation and changes derived from gameplay in young tennis players.

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.

Determinant Physical Factors of Tennis Serve Velocity: A Brief Review.

PURPOSE: To review the main physical aspects that could positively or negatively influence serve velocity (SV). METHODS: An examination of existing literature including studies analyzing positive (biomechanical aspects, anthropometrics, range of motion, strength, and power) and negative (competition-induced fatigue) associations to SV are summarized in this review. RESULTS: Aspects such as lower-leg drive, hip and trunk rotations, upper-arm extension, and internal rotation seem to be the major contributors to racquet and ball speed. Favorable anthropometric characteristics, such as body height, arm length, and a greater lean body mass, seem to positively influence SV. Also, strength indicators such as maximal isometric strength and rate of force development in specific joint positions involved in the kinetic chain alongside upper-body power seem to be related to faster serves. On the other hand, the effects of prolonged or repetitive match play may impair the aforementioned factors and negatively influence SV. CONCLUSIONS: Following specific serving models that seem to enhance velocity production and efficient motion is highly recommended. Moreover, achieving a higher impact point, alongside shifting body composition toward a greater lean body mass, will most likely aid toward faster serves. Programs aiming at improving maximal isometric strength and rate of force development in specific positions involved in the kinetic chain including stretch-shortening cycle predominance and the mimicking of the serve motion seem of great interest to potentially increase SV. Effective recovery and monitoring of these variables appear to be essential to avoid impairments produced by continued or repetitive competition loads.