Physical determinants, intercorrelations, and relevance of movement speed components in elite junior tennis players

Change of Direction Asymmetry in Youth Elite Tennis Players: A Longitudinal Study

Longitudinal investigations into the development of inter-limb asymmetry in sports are scarce. This study examined the development of change of direction (COD) asymmetry magnitude in youth elite tennis players. Dominant (overall best performance) and non-dominant (best performance on the other side) scores and COD asymmetry magnitude were quantified annually (up to six years) in 323 male and 235 female players (ages 6 to13 years). Linear mixed effects regression models examined the development of COD performance and asymmetry magnitude according to players' chronological age and sex. Kappa coefficients examined the consistency for the direction of asymmetry across test occasions. Regardless of sex, COD performance significantly improved (p<0.001) while COD asymmetry magnitude significantly decreased (- 0.17±0.87% / year) with increasing chronological age. Regardless of age, males showed significantly lower COD times (- 0.111±0.091 s) and lower COD asymmetry magnitude (- 0.30±1.00%) compared to females. The slight and poor (k-value=0.02-0.00) kappa coefficients for males and females, respectively, highlight the direction specificity of functional asymmetry. These data show that whereas performance of the COD test improved, the magnitude of COD asymmetry declined across chronological age in youth tennis players.

The plyometric treatment effects on change of direction speed and reactive agility in young tennis players: a randomized controlled trial

Aim: The aim of this paper is to determine the effect of 6 weeks of plyometric training on speed, explosive power, pre-planned agility, and reactive agility in young tennis players. Methods: The participants in this study included 35 male tennis players (age 12.14 ± 1.3 years, height 157.35 ± 9.53 cm and body mass 45.84 ± 8.43 kg at the beginning of the experiment). The biological age was calculated and determined for all participants. 18 of the participants were randomly assigned to the control group, and 17 were assigned to the experimental group. Running speed (sprints at 5, 10, and 20 m), change of direction speed (4 × 10, 20 yards, t-test, TENCODS), reactive agility (TENRAG), and explosive power (long jump, single leg triple jump, countermovement jump, squat jump, and single leg countermovement jump) were all tested. The Mixed model (2 × 2) ANOVA was used to determine the interactions and influence of a training program on test results. Furthermore, Bonferroni post hoc test was performed on variables with significant time*group interactions. Results: The results of this research indicate that an experimental training program affected results in a set time period, i.e. 5 out of total 15 variables showed significant improvement after experimental protocol when final testing was conducted. The experimental group showed significantly improved results in the 5 m sprint test in the final testing phase compared to the initial testing phase, this was also the case in comparison to the control group in both measurements. Furthermore, the experimental group showed significant improvement in the single leg countermovement jump in the final test, as well as in comparison to the control group in both measurements. The change of direction speed and reactive agility test also exhibited significant improvement in the final testing phase of the experimental group. Conclusion: The results of this research indicated that a 6-week program dominated by plyometric training can have a significant effect on the improvement of specific motor abilities within younger competitive categories. These results offer valuable insights for coaches in designing diverse tennis-specific scenarios to enhance overall performance, particularly focusing on the neuromuscular fitness of their players.

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.

Effectiveness and Kinematic Analysis of Initial Step Patterns for Multidirectional Acceleration in Team and Racquet Sports

The ability for quick multidirectional accelerations is crucial for athletic performance in team and racquet sports. So far, there has been little research dedicated to different initial step patterns usually applied by players. Therefore, the present study investigated the kinematic characteristics and effectiveness of the following step patterns: Jab Step (JS), Pivot Step (PS), Gravity Step (GS) and Counter Step (CS). Twenty-two male competitive team and racquet sport athletes completed maximum lateral accelerations utilizing the step patterns. Following familiarization with each step pattern, three 5 m sprints (5 m STs) into both directions (left & right) were completed. Sprint times, the translation of the center of mass (CoM) and joint angles were obtained using three-dimensional motion analysis. 5 m STs of the CS were faster compared to the GS and PS for both directions. A detailed distance-time analysis revealed that for shorter distances only the JS was faster than the GS. Regarding the sequence in which the maximum angular velocities (max. w → ) in the hip, the knee, and the ankle were reached during the push off, there was a proximal-to-distal sequence for the JS and the CS, but a distal-to proximal sequence for the GS and the PS. The results reveal that the JS and the CS are superior for accelerations towards the lateral direction. Specifically, they indicate that the JS is more suitable for covering very short distances and the CS is superior for covering further distances. In addition, the distal-to-proximal sequence of max. w → during the push-off in the GS and the PS might indicate lower kinematic efficiency.

Relevance of force-velocity and change of direction assessments for the ranking position in elite junior tennis players

Purpose

This study aimed to correlate sprint mechanical parameters (SMP) of a linear sprint (LS) and a tennis specific modified 505 (Tm505) change of direction (CoD) test obtained with a motorized resistance device (MRD) to the current tennis ranking position (RP).

Methods

107 male and 86 female elite junior tennis players nationally ranked in the German Tennis Federation between 10 and 18 years participated in the study. According to their age at peak height velocity (PHV), players were divided into pre-PHV, circa-PHV, and post-PHV groups. SMP were derived from instantaneous time-velocity data of two 20 m all-out LS measured with 333 Hz. Further, mean values from two Tm505 trials with constant 3 kg loading over acceleration-deceleration (1a) and reacceleration (1b) phases were measured with an MRD. SMP of LS and CoD measurements were partially correlated with the current RP in the overall national ranking by controlling for biological maturation.

Results

Low to moderate correlations (r_s  = -0.1 to -0.3) were found between SMP and the RP in all male and female age groups. Correlations of the CoD measurements were overall more pronounced, particularly in girls (r_s  = -0.44). All linear SMP, like maximal theoretical force (F₀; N/kg), and maximal theoretical velocity (v₀; m/s), maximal power (P_max; W/kg), improved over maturation for both genders with P_max being most important for sprint performance. Further, P_max was shown to correlate with the girls ranking position (r_s  = -0.31). During the Tm505, matured players achieved significantly faster overall total and CoD times. Positioning of CoM before CoD enlarged over maturation and was found to correlate to the RP in both sexes. In addition, nearly all SMP significantly correlated to the primary performance outcomes in the Tm505 test in both genders (r = -0.3 to -0.6).

Conclusion

CoD performance has a moderate and higher impact on tennis performance compared to LS. CoD performance as well as P_max achieved a higher relevance for the ranking position predominantly in girls compared to boys. Hence, particularly P_max as well as the transfer to on-court CoD motor skills should be a central training goal in elite junior tennis players besides technical skills and should depend on maturation status and gender.