Luiz Fernando Ramos-Silva

The aim of the study was to compare isokinetic performance (PT) of knee extensors (ext) and flexors (flex), H:Q ratio, and PT asymmetry in young soccer players based on somatic maturation. 80 soccer players (aged 12-17) were sampled, classified as pre-PHV (n=19) and post-PHV (n=61). Isokinetic dynamometry assessed knee extensors/flexors at 60º/s. Pre-PHV had lower body mass/height than post-PHV (P < 0.001). Pre-PHV exhibited lower PT for dominant and non-dominant leg in ext and flex (P < 0.001). No differences in asymmetry (ext: 31.6% vs 31.1%; flex: 31.6% vs 34.4%) and H:Q ratio (dominant: 42.1% vs 32.8%; non-dominant: 26.3% vs 39.3%) between PHV groups, where asymmetry was considered >15%, and cutoff points for each limb H:Q were set at ≥60%. Study showed increased isokinetic performance according to PHV, but no effect on asymmetries and H:Q ratio.

Luiz Fernando Ramos-Silva , Julio Cesar Costa, Paulo Henrique Borges, Felipe A Moura, Rafael Deminice, Donizete Cícero Xavier de Oliveira , Raul Osiecki, Enio Ricardo Vaz Ronque Predictors of Ball Velocity in the Sitting Volleyball Serve: A Causal Analysis Int J Sports Med 2023; 44: 664–672 DOI 10.1055/a-2046-2747 Published online: 19.05.2023 The table 2 has been corrected. This was corrected in the online version on october, 19.10.2023 Article published online: 23 October 2023 © 2023. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

This study aimed to observe the relationships between the maturity status on the network-based centrality measures of young athletes in small-sided soccer games (SSG). The study included 81 male players (14.4 ± 1.1 years). Measurements included height, sitting height, body mass, and bone age (TW3 method). The applied protocols were the following: Countermovement Jump (CMJ), Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1), Repeated Sprints Ability (RSA), observational analysis of techniques, and interactions performed by players in SSG. The relationship between the set of evaluated variables within each maturity status was obtained from the correlational analysis of networks (P < 0.05). The maturity status explained a significant portion of the variance in body mass (η² = 0.37), height (η² = 0.30), sitting height (η² = 0.30), and performance on the YYIRT1 (η² = 0.08), CMJ (η² = 0.14), and RSA (η² = 0.13). No effect of maturity status on network-based centrality measures of young athletes was identified (P > 0.05). For the late maturity group, there was a correlation between the degree of centrality and physical growth indicators (r_mean = 0.88). For players with maturation “on time”, physical growth indicators relate to the degree of prestige (r_mean = 0.36). It is concluded that body size and bone age impact how late and on-time maturity groups interact within the match.

This study verified the relationship between body size and skeletal age (SA) with the behavior of blood markers of muscle damage and delayed onset muscle soreness (DOMS) after a soccer match in the U-13 and U-15 categories. The sample consisted of 28 soccer players in the U-13 and 16 in the U-15 categories. Creatine kinase (CK), lactate dehydrogenase (LDH), and DOMS were evaluated up to 72 h after the match. Muscle damage was elevated at 0 h in U-13, and from 0 h to 24 h in U-15. DOMS increased from 0 h to 72 h in U-13 and from 0 h to 48 h in U-15. Significant associations of SA and fat-free mass (FFM) with muscle damage markers and DOMS were observed only in U-13, specifically at time 0 h, when SA explained 56% of CK and 48% of DOMS and FFM explained 48% of DOMS. We concluded that in the U-13 category, higher SA is significantly associated with muscle damage markers, and increase in FFM is associated with muscle damage markers and DOMS. Furthermore, U-13 players need 24 h to recover pre-match muscle damage markers and more than 72 h to recover DOMS. In contrast, the U-15 category needs 48 h to recover muscle damage markers and 72 h to recover DOMS.

Aim: The aim was to compare performance in specific-skill tests and motor coordination between groups with different technical efficiency and verify possible variables related to specific skills and motor coordination that contribute to discriminate players into high- and low-technical efficiency. Methods: The sample consisted of 82 young soccer players (12-15 years). Body size, bone age, motor performance tests, soccer-specific skill tests, and frequency of technical actions in SSG were analyzed. Statistic cluster-derived ANOVA F was used to identify which variables related to technical action most contributed to classifying subjects with similar performance. Discriminant analysis (Stepwise Method) was used to verify which predictor variables discriminated players into groups of low- and high-frequency technical actions in SSG. Statistical significance was set at 5%. Results: The group of high technical efficiency presented better performance in motor tests, shuttle run (P = 0.04; ES = −0.55), jumping laterally (P = 0.02; ES = 0.58), kicking speed (P = 0.03; ES = 0.60), soccer-specific skill tests, leading the ball in a straight line (LBSL) (P = 0.01; ES = −0.75), and zig-zag ball control (ZZBC) (P = 0.04; ES = −0.55); variable leading the ball in a straight line correctly discriminated 60% of players into high- and low-frequency groups. Conclusion: The frequency of technical actions in SSG was poorly influenced by motor performance and specific skill tests, and only the LBSL test correctly classified players of different frequencies of technical actions in SSG.