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This study aimed to determine the correlation between interlimb asymmetries and physical performance metrics in adolescent female tennis players., Methods: Twenty-five female tennis players (age: 13.29 ± 0.98 years; weight: 52.52 ± 7.31 kg; height: 162.91 ± 6.02 cm) consented to participate in this study. Their performance was evaluated using various variables, including bilateral and unilateral countermovement jump (CMJ), bilateral and unilateral horizontal jump (HJ), 180° change of direction (180COD) conducted with both the right and left legs, and a 20 m sprint. The systematic bias was evaluated by one-way repeated measure analysis of variance, Pearson's correlation test for relationships between variables, and the kappa coefficient for consistency in the asymmetrical direction., Results: Significant relationships were found between CMJ asymmetry and the variables HJR (r = -0.47) and HJL (r = -0.44). In addition, significant relationships were found between HJ asymmetry and the variables CMJR (r = -0.60) and CMJL (r = -0.54), HJR (r = -0.64), HJL (r = -0.67), CMJ (r = -0.55), and HJ (r = -0.52)., Conclusion: Jumping tests are important indicators of performance loss in female tennis players. In addition, no significant correlation was found between the 180COD and performance tests, suggesting that asymmetries in COD do not affect jump performance or speed. Based on these results, it is recommended to integrate individualized programs for each athlete to reduce asymmetries.

The purpose of this study was to assess the external load demands in futsal, considering both home and away matches and their outcomes, in order to plan microcycles throughout the season based on the external load of each match. The external load of 10 players from a First Division team in the Spanish Futsal League was recorded throughout 15 official matches in the first half of the league championship. The players' external load was monitored using OLIVER devices. To analyse the influence of the match outcome and location on the external load, a univariate general linear model (GLM) analysis was conducted with Bonferroni post hoc. There are no differences between the variables neither comparing results nor location factors, except for accelerations of 2 to 3 m/s 2 (m) per minute and the number of accelerations of 2 to 3 m/s 2 per minute, reporting higher value winnings at home than away ( p < 0.05). The location and results are not factors that influence on external load in futsal matches, except the number and distance performed in accelerations and distance covered at a low to medium speed. These findings are important for planning microcycles and providing the appropriate dosage to each player to achieve optimal performance in matches.

Tennis is an individual sport characterised by high-intensity action, including sprints and changes of direction (COD). However, there is a gap in the knowledge of limb asymmetries in adolescent tennis players and their association with performance. The aim of this study was to investigate the relationship between asymmetry in vertical and horizontal jump tests (CMJ and HJ) and COD with lower limb performance variables in adolescent tennis players. Forty-five adolescent tennis players (age: 13.81 ± 1.08 years; height: 167.64 ± 9.9 cm; body mass: 57.48 ± 10.94 kg; body mass index: 20.27 ± 2.18 kg/m 2 ) performed the CMJ test (unilateral and bilateral), horizontal jumps (unilateral and bilateral), 25 m sprint, and 180° COD test. The single-leg countermovement jump showed the greatest asymmetries among the different tests (6.62 ± 9.35%). Notable negative relationships were found between CMJ asymmetry and COD asymmetry with unilateral horizontal jump variables ( r = -0.30 to -0.53). In addition, CMJ asymmetry showed notable relationships with CMJR ( r = 0.49) and COD180R ( r = 0.29), whereas COD asymmetry showed a notable relationship with COD180L ( r = 0.40). On the other hand, HJ asymmetry showed no notable relationships with any variable. The main findings of this study indicate that greater imbalances in the CMJ and COD tests are associated with a reduced capacity to perform unilateral horizontal jumps. These results suggest the incorporation of training protocols to reduce interlimb asymmetries in growing athletes to improve their performance. This practical application is important for coaches and physical trainers who aim to improve the physical performance of adolescent tennis players. Greater asymmetry results in a reduced ability to produce unilateral horizontal force.

Studies show that although female soccer players often have shorter change of direction (COD) deficits than males, indicating different biomechanical profiles, there is a lack of research on the impact of physical metrics on COD performance in females. The purpose of this work was to analyse whether performance metrics based on speed and jumping could explain the variation in %CODD in young female soccer players. Thirty-three highly trained adolescent female soccer players with an age of 16 ± 0.95 years, a body mass of 55.7 ± 7.22 kg, and a height of 160.4 ± 5.22 cm performed COD180 tests, 10 m and 30 m sprint tests, single-leg countermovement, and horizontal jumps. Acceleration in the first 10 m of a sprint was identified as a significant predictor of COD180 performance (R 2 = 28%), (R 2 = 50%), ( p < 0.01), indicating that early sprint performance may largely determine an individual's ability to change direction. However, no predictors were found for %CODD. Significant correlations were observed between COD180 performance and %CODD, acceleration, linear speed, and horizontal jump performance ( r = -0.59 to 0.70; p < 0.05). The study suggests that specific physical performance metrics, particularly early acceleration, are crucial for enhancing COD skills in female soccer players, emphasizing the need for targeted training interventions.

Background: The objective of this study was to assess the effectiveness of neuromuscular training on the performance of highly trainer junior tennis players., Methods: Twelve male tennis players (age: 13.4 ± 0.36 years; weight: 50.2 ± 6.29 kg; height: 163 ± 4.41 cm) participated and were randomly divided into two groups. The experimental group (EG) performed neuromuscular training that included exercises for speed, strength, throws, agility, jumps and coordination twice a week for a duration of 10 weeks. Performance was evaluated using various variables, including bilateral and unilateral countermovement jump, 30 cm drop jump and horizontal jump, 505 change of direction test conducted with both the right and left legs, 20-m sprint, and overhead 3 kg medicine ball throw. Asymmetries were also evaluated during the unilateral tests. The impact of the training was assessed through the utilization of ANCOVA tests and effect size measurements., Results: The results indicated a significant enhancement in the EG, specifically in bilateral vertical jump and horizontal jump, as well as explosive strength and speed. Conversely, the control group (CG) did not display similar advancements. Furthermore, there was no increase in asymmetries., Conclusion: This suggests that the implementation of a neuromuscular training program could prove to be an effective approach in enhancing explosive power in the lower limbs among young competitive tennis players. Finally, this training program could contribute to the enhancement of their physical attributes in lower body of young tennis players., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)