Introduction: Muscular strength is an essential capacity for soccer players; however, the profile of this capacity has not yet been clearly established in young players. Objective: To compare muscular strength performance in the countermovement jump (CMJ) task and the presence of lower limb asymmetry among soccer athletes of the under 15 (U15), under 17 (U17) and under 20 (U20) categories, and between two teams of different competitive levels. Methods: One hundred and fifty one young soccer players of three different categories (U15, U17 and U20) from two teams in the Brazilian first and second divisions performed six vertical jumps in a system of two force plates. Ground reaction force (GRF) was used to calculate jump height and to obtain the variables Peak force (FMAX), Impulse (I) and Peak power (PMAX) with regard to body mass and the respective asymmetry values. Results: No differences were found in the performance and asymmetry variable between the categories (Jump height: p=0.23; FMAX: p=0.15; I: p=0.11; PMAX: p=0.32; FMAX asymmetry: p=0.21; I asymmetry: p=0.58; PMAX asymmetry: p=0.58). The first division club had higher muscle strength and asymmetry values than the second division club (Jump height: p<0.01; I: p<0.01; PMAX: p<0.01; FMAX asymmetry: p<0.01; I asymmetry: p<0.01; PMAX asymmetry: p<0.01), except for FMAX (p=0.63). No variable had an interaction effect (club x category). Conclusion: As categories progress, jump height, relative I, PMAX and FMAX values and their respective asymmetries are stable. The asymmetry and strength performance of the first division club were higher than that of the second division club, except for FMAX, indicating that the competitive level may influence strength performance and the development of asymmetry. Level of Evidence II; Diagnostic study – Investigating a diagnostic test.
This article evaluates the effect of a supplementary resistance training program on passive and active hip external rotation on a ballet group. Fifteen Brazilian ballet dancers participated in the study. The passive hip external rotation was evaluated by a hip articular mobility test and the active hip external rotation in the first position en dehors in a self-selected angle. The resistance training protocol was based on The Best Performance Movement exercise method. Four 20-minute sessions per week were performed for three months. The paired t-test was performed to compare the passive and active hip external rotation pre- and post-training, with a significance level of 0.05. The paired t test showed that hip active external rotation improved after the resistance training, suggesting that the hip external rotation is muscle strength dependent.
Strength asymmetry may be related to an increased risk of injury and to a reduction in performance of soccer players. The purposes of this study were to verify if there is a difference in asymmetry prevalence and to determine the profile of strength asymmetry in four different youth soccer categories diagnosed by the single leg hop test. A total of 111 male soccer players from four different youth categories: pre-infantile (n = 34), infantile (n = 20), juvenile (n = 31) and junior (n = 26) of a national soccer team engaged in the study.Each soccer player made three valid attempts with each lower limb and the attempt with the best performance, i.e. greater horizontal distance, was used to calculate the symmetry index. To compare the symmetry index between the categories, the one-way ANOVA test with a Bonferroni post hoc was used, and the χ 2 test was used to verify the prevalence of symmetric or asymmetric soccer players among the categories (p < .05). There were no differences in the symmetry index (F (3.107) = 1.229; p > .05), nor were differences in the prevalence asymmetric players (χ 2 (111) = 1.574; p > .05) between the categories. It was concluded that the older soccer players of the different youth categories did not present a higher prevalence of asymmetry than the younger soccer players when evaluated at the beginning of the season.
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