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 XX(X): 000-000, 2018-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 highlight 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.

Movement speed is considered essential for success in elite tennis. The aim of the present study was to develop a model of movement speed components and quantify their ageand gender-related relevance for tennis performance. Physical testing data obtained from 1,434 nationally ranked junior squad tennis players were divided according to the age at peak height velocity (YPHV) into two age groups (pre-PHV: n=103 girls, 11.7 ± 0.6 yrs.; n=466 boys, 12.7 ± 1.0 yrs.; post-PHV: n=524 girls, 14.2 ± 1.4 yrs.; n=344 boys, 15.3 ± 1.2 yrs.). After assessing anthropometrics and maturity status, all players passed a series of standardized physical tests on an indoor hard court. All data were z-standardized, filtered and sorted by gender, maturity level, and ranking position. The structuring of the speedrelated performance parameters resulted in four factors ("Elementary Speed", "Jumping Power", "Linear Speed", and "COD Speed"), which were then confirmed by factor analysis. The correlation of these factors to the national ranking position was mostly significant but rather low, with "Linear Speed" reaching the lowest (r=0.10-0.18) and "COD Speed" the highest correlation (r=0.22-0.34). Path analytic models revealed "COD Speed" as the most important factor, which is strongly influenced by "Jumping Power" and "Linear Speed," with medium effect sizes, while "Elementary Speed" affects this factor only slightly. It can be concluded that the relationship between movement speed and junior players' tennis ranking is lower than expected. The development of "COD Speed" should be prioritized during testing, training, and talent identification, independent of age group and gender. Highlights. Performance parameters for 1,434 junior players with national rankings were analyzed and assigned to four superior factors. . The impact of the factors on the ranking position, as well as the internal causal relationships, were investigated via path analysis. . "COD Speed" was the most impactful factor for tennis performance and was strongly influenced by "Linear Speed" and "Jumping Power."

Our study aimed to examine athletics, training characteristics, and prevalence of musculoskeletal symptoms of male junior tennis Davis Cup players (DC) in comparison with their regional counterparts, as well as to evaluate the impact of age and performance level on training characteristics. Twelve junior DC (male) and two samples of regional squad players (RS1 n ¼ 60 males, n ¼ 47 females; RS2 n ¼ 59 males) participated in a physical testing, an interview for data evaluation on training characteristics, and a questionnaire survey of orthopedic injury frequency. Results indicate higher physical performance levels (effect size (ES) 0.75-1.26) and training volumes in DC (ES 1.23-1.66). In DC, significant relationships were found between total training volume and tennis ranking (r ¼ À0.78), age and physical training volume (r ¼ 0.82), and age and total training volume (r ¼ 0.62). Injury frequencies showed moderate to high prevalence with no differences (p > 0.05) between DC and RS. Given the demands of elite tennis and the important role of service in the modern game, more efforts are necessary to develop training prescription for both performance enhancement and prevention strategies.

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.

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