Asimakidis, ND, Dalamitros, AA, Ribeiro, J, Lola, AC, and Manou, V. Μaturation stage does not affect change of direction asymmetries in young soccer players. J Strength Cond Res 36(12): 3440-3445, ...2022-This study examined whether the stage of biological maturation can affect interlimb asymmetries during a change of direction (COD) test. Seventy-six young soccer players were divided into 2 different groups according to their peak height velocity stage (PHV): pre-PHV (n = 45, age = 11.8 ± 1.2 years, height = 149.8 ± 9.3 cm, body mass = 43.9 ± 11.2 kg) and post-PHV (n = 31, age = 14.4 ± 0.9 years, height = 170.0 ± 4.9 cm, body mass = 61.5 ± 8.9 kg). Subjects performed a 505 test to measure the completion time in both directions and a 20-m maximum sprint test. Change of direction deficit (CODD) was used as a measure for isolating COD ability. An independent sample t-test detected no significant differences between the asymmetry index values for the 505 test completion time when the pre-PHV group and the post-PHV group were compared (-3.49 ± 2.49% vs. -3.45 ± 2.47%, effect size ES = 0.02, p = 0.923). Similarly, the CODD asymmetry index indicated no differences between the 2 groups (-8.21 ± 5.95% vs. -7.37 ± 5.12%, ES = 0.15, p = 0.457). A paired sample t-test revealed that the values of the CODD asymmetry index were larger than those of the 505 asymmetry index (-7.88 ± 5.61% vs. -3.49 ± 2.46%, ES = 1.09, p < 0.001). According to these results, maturational status has no influence on the interlimb asymmetries of COD ability. Furthermore, subjects showed greater asymmetry values in CODD compared with the 505 test completion time, reinforcing that the evaluation of COD asymmetries should be based on CODD. As interlimb asymmetries are not altered during the maturation process, practitioners should address abnormal COD asymmetries early on during athletes' development processes.
The simultaneous improvement of both form and outcome of sport skills is a challenge for every instructor since these are competing goals, especially for novices, and in the early stages of learning ...the improvement of movement form is usually more important than outcome. However, when novices have both goals, outcome usually prevails over form. External over internal focus of attention has been proposed by many researchers as an effective method for the development and learning of movement form or outcome. In this study, 57 girls were randomly divided into 2 experimental groups (external and internal) and a control group. All groups performed a pre-test. The two experimental groups followed an intervention program for 12 training units (6 weeks X 2 times a week). A post-test and a transfer test followed two weeks later. Data were analysed by factorial ANOVA (3 groups X 3 measurements) with repeated measurements of the last factor, followed by a post-hoc Tukey test. Both experimental groups, but not the control group, improved their performance in both form and outcome from pre-test to post-test and transfer test. The external focus group scored better in both form and outcome than the internal focus group in the post and transfer tests. It seems that external focus drives a subconscious motor control that results in greater movement automaticity and improves both form and outcome of sport skills. It is concluded that the external focus method is appropriate to develop both form and outcome of perceptual-motor skills.
This study aimed to develop a test for measuring athletes’ performance. Logical, content, construct, criterion validity, as well as reliability, were examined. Three beach volleyball experts ...evaluated how well the test evaluates the shot skill accuracy according to their judgment (logical validity). A group of eight beach volleyball experts analyzed the test and rated it on a scale of 1 to 7 regarding the relevance of the content as a measure of beach volleyball athlete’s accuracy, the average score was calculated at 6.75 (SD=0.46) (content validity). 60 beach volleyball players divided into three equal groups of novices, intermediates, and experts were asked to undergo the test on two separate days. A one-way ANOVA between the three groups was performed, which indicated that the mean scores of the three groups differed significantly (p<0.001 for both days): experts achieved better scores than intermediates who in turn scored better than novices (construct validity). The athletes’ scores were correlated with their proficiency level, using the Pearson Correlation test, which indicated very high positive (Day-1: r=0.956, n=60, p<0.001; Day-2: r=0.953, n=60, p<0.001) (criterion validity). The intraclass correlation coefficient was calculated between Day-1 and Day-2 and was found equal to 0.980 for average measures (p<0.001) and 0.961 for single measures (p<0.001). In conclusion, the requirements for logical, content, construct, criterion validity, and reliability have been met. Therefore, the line shot attack test can be used as a valid and reliable measurement instrument for evaluating the performance of beach volleyball athletes.
This study aimed to investigate the beach volleyball set and technical performance indicators that best discriminate between winning and losing elite women’s teams in set according to the final score ...differences of the set. The data have been collected from all sets played (N = 236) in the women’s beach volleyball 2022 World Championship. Cluster analysis established two types of 21 points sets (S-21): balanced (S-21B) with a difference from 2-5 points and unbalanced (S-21U) with a difference >5 points. A discriminant function analysis indicated which skill(s) significantly contribute to winning in each type of set. The results of this study revealed that the teams that won S-21B, S-21U and S-15 had better performance than their opponents in set indicators (attack, block, serve, opponent errors) and technical indicators (attack kill percent, attack efficiency, and serve efficiency). Attack points and attack kill percent were the most important predictors of a team's success in terms of set and technical indicators, respectively. In summary, the attack kill percent is the most important indicator in elite women’s beach volleyball in every type of set. However, serve aces per set point significantly increases the probability of winning a set in every type of 21-point set, while block per set points contributes equally significantly in 15-point sets. Despite the high level of blocking, women's teams must avoid attack errors to improve their chances of winning a set. The study’s findings highlight the importance of the offensive ability to win a set, in women’s elite beach volleyball.
The purpose of this study was to explore the match and technical indicators between winning and losing teams in the Olympics and World Championships (2016–2021) depending on the final score of the ...matches. A total of 273 volleyball match reports were analyzed from the Men's Olympics (2016 and 2021) and World Championships (2014–2018). Discriminant function analysis determined which skill(s) contributed significantly to winning in matches with various score types. This study showed that for 3- and 4-set matches attack was the best predictor for team's success, while block and serve had also meaningful contribution. In 5-set matches serve and block points were the main predictors of a team's success. The results on the importance of scoring skills highlight the necessity of sustained trainability of all match actions, not favoring one, such as attack, too much. The essential for this balance is confirmed by the fact that teams do not increase their probability of winning a match by success only in attack, but also in the other terminal actions such as serve and block.
The present study is an attempt to evaluate directly the effect of explicit, implicit and analogy instruction on decision-making skills among novices under stress conditions. 60 young novices, aged ...10-11, were randomly selected and assigned to three experimental groups and a control group. A field and a laboratory test were conducted to evaluate decision-making on the volleyball serve skill (decide and move). Once the four groups completed the pre-test, the three experimental groups participated in the intervention programme consisting of 12 training units (4 weeks X 3 times per week). A post-test, a retention test, and a stress test were also applied to all groups. All experimental groups improved and retained decision-making scores in both the laboratory and the field tests. Comparing the groups showed that the analogy learning group achieved a higher score than the implicit, explicit, and control groups in the post-test and retention test. Analogy and implicit learners appear to be unaffected by stress conditions, while the opposite is true of the explicit learners' performance, which decreased in both in the laboratory and the field tests. Ιt seems that if taught by analogy-based instructions, novices may perform better at both decision-making and motor skills, which indicates that they are under less cognitive demand, even under stress conditions.
Expression of Concern
International journal of sport and exercise psychology,
10/2021, Letnik:
ahead-of-print, Številka:
ahead-of-print
Journal Article
Background: Front crawl and backstroke share similar trunk rotating characteristics and tempt coaches to transfer teaching parts from one stroke to the other intuitively. However, the degree of ...similarity has yet to be determined. The coordination of the pelvis and the 7th cervical vertebrae (C7), during yaw and roll rotation, when sprint swimming front crawl, and backstroke was studied. Methods: Thirty-four swimmers were assessed on their performance in25m-sprint of each stroke. Using inertial sensors, each segment’s time series of angular displacement was calculated. Their amplitudes, mean autocorrelation values, max cross-correlation coefficient, phase lag, and relative power at the main frequency were analyzed. For all comparisons, the p-value was set to 0.05. Results: Pelvis yaw and roll and C7 roll amplitudes were greater at backstroke, C7 yaw was greater at front crawl. Autocorrelations ranged from 0.79 to 0.82 except for the pelvis at front crawl in yaw which was 0.72±0.16. Relative power at the main frequency ranged from 47% to 52% except for the yaw pelvis’ at the front crawl which was lower (32.81±14.09%). Backstroke had larger mean values in all cases and roll had larger mean values than yaw. Cross-correlation between the two segments yielded higher values at roll. At roll direction, the leading segment in the front crawl was the pelvis while in backstroke, it was the C7 which was true in all cases. In all cases, the coupling was slightly deviating from in-phase mode except from backstroke yaw which yield phase lag values of -13.35±1.14% of stroke cycle time. Conclusions: Although both strokes share similar characteristics their intersegmental coupling differs. The findings of the study imply that proper focus should be given to enhance only a positive transfer of learning between the two strokes.
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