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

Acute effects of in-step and wrist weights on change of direction speed, accuracy and stroke velocity in junior tennis players

The main aim of this study was to investigate the acute effects of the use of a weighting set (Powerinstep®) on measures of stroke velocity (StV), accuracy and change of direction speed (CODS) in junior tennis players. A within-subjects design was used to evaluate seventeen (6 female and 11 male) tennis players (mean ± SD; 16.5 ± 1.3 years old; 1.75 ± 8.4 m; 67.0 ± 8.1 kg; 22.04 ± 1.8 kg/m2) on StV of three specific tennis actions (serve, forehand and backhand) and CODS for the following conditions: wearing a 50, 100, 150, 200 g weight or no weight at all (baseline). No significant differences were found between conditions for forehand (F = 0.412; p = 0.799), backhand (F = 0.269; p = 0.897) and serve (F = 0.541; p = 0.706) velocity and forehand (F = 1.688; p = 0.161), backhand (F = 0.567; p = 0.687) and serve (F = 2.382; p = 0.059) accuracy and CODS (F = 0.416; p = 0.797). Small-to-moderate effect sizes (ES) negatively affecting StV when using 200 g compared to the baseline (ES = 0.48, 0.35 and 0.45) could be observed. Moderate (ES = -0.49) and trivial (ES = -0.14 and -0.16) ES for a higher accuracy score were noticed in serve, forehand and backhand 100 g compared to the baseline. Moreover, small ES (ES = 0.41) for improvement in 200 g CODS comparing to baseline conditions were found. These results indicate that the use of a weighting set does not significantly affect StV or CODS respectively. Notwithstanding, small-to-moderate changes show impact in accuracy and no variance in velocity production when using 100 g alongside faster execution in CODS when using 200 g.The research leading to these results has been conducted using funds from the agreement between the Universitat de Vic – Universitat Central de Catalunya and Powerinstep, SL. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Relationship between Heart Rate and the Scoreboard during a Relegation Playoff

En los deportes de equipo, el estudio de la frecuencia cardíaca (FC) resulta fundamental para la optimización del rendimiento y la prevención de lesiones, ya que nos permite conocer algunas de las demandas fisiológicas generadas por la práctica deportiva y el nivel de carga interna. El objetivo del presente estudio fue conocer la relación existente entre la FC y el marcador del partido, así como el número de acciones que se realizan en cada uno de los estratos generados, en función de la diferencia de puntos en el marcador en jugadoras de baloncesto amateur durante una fase de descenso. Para ello, se analizó la FC siguiendo los criterios propuestos por McInnes, Carlson, Jones y McKenna (1995) en una muestra de diez jugadoras (n = 10) de Copa Catalunya, durante los 10 partidos oficiales de una fase de descenso. Seguidamente, se relacionó la FC con el marcador y con la duración de las acciones de juego en cada momento del partido. Los resultados muestran valores de FC que fluctúan entre el 88.9% y el 92.2% de la FC máx. Además, se observaron diferencias significativas en cuanto a la diferencia en el marcador (p < 0.05), en cada uno de los 3 estratos analizados. En cuanto a la relación con las variables temporales de juego, se observaron diferencias significativas únicamente en las posesiones largas (17-24 s) (p < 0.01). Las conclusiones de este estudio sugieren que la diferencia de puntos en el marcador y las acciones de juego de duración comprendida entre los 17-24 s tienen una influencia directa sobre la FC, modificándose esta en función de la diferencia de puntos e influyendo en las demandas fisiológicas de las jugadoras.In team sports, the study of heart rate (HR) is fundamental for optimizing performance and preventing injuries since it allows us to learn about some of the physiological demands generated by doing sport and the level of internal load. The purpose of this study was to explore the relationship between HR and the scoreboard for the game as well as the number of actions performed in each of the strata generated depending on the difference in points on the scoreboard in amateur basketball players during a relegation playoff. To do this HR was analyzed, following the principles proposed by McInnes, Carlson, Jones and McKenna (1995), in a sample of ten players (n = 10) in the Catalan Cup during the 10 competitive matches during a relegation playoff. Next, HR was related to the scoreboard and the duration of play actions at each moment during the game. The results show HR values that range between 88.9% and 92.2% of HR max. In addition, significant differences were observed with respect to the points difference on the scoreboard (p < 0.05) in each of the 3 strata analyzed. As for the relationship with the play time variables, significant differences were observed only in long possessions (17-24 s) (p < 0.01). The conclusions of this study suggest that the difference in points on the scoreboard and play actions lasting 17-24 s have a direct impact on HR, which changes as a function of the points difference and influences the physiological demands on the players

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

The Effectiveness of Shoulder Mobility and Strength Programs in Competitive Water-Polo Players

Background: Water-polo is the water sport with the highest incidence of injuries, with shoulder pain being the most common one. The understanding of risk factors and guidance on preventive measures is essential in this sport discipline. The aim of this study was to determine the effects of a specific 6-week training plan on range of motion (ROM) and joint strength levels in a group of professional water-polo players. Methods: Quasi-experimental study with a sample of 28 participants (age: 20.1 ± 2.5 years; height: 176.9 ± 6.2 cm; body mass: 74.6 ± 8.1 kg). Three study groups, which consisted of one control group and two experimental groups, were established. Two repeated measurements, pre and post intervention, were performed. During these measurements, ROM of the glenohumeral joint was analyzed both in external (ER) and internal (IR) rotation, as well as the maximal isometric strength. Conclusions: The application of a training program improved glenohumeral joint ROM. ER and IR evolve differently in both shoulders. ER improved only in the throwing arm only in the group undergoing intervention but for the non-dominant side, improvements were observed in both ER and IR, regardless of whether or not they had followed the intervention plan. No improvements were observed in either the isometric strength or contralateral asymmetries