Repeated Sprint Ability in Young Basketball Players: Multi-direction vs. One-Change of Direction (Part 1)

The aim of the present study was to examine the reliability of a novel multi-direction repeated sprint ability (RSA) test [RSM; 10 7 (6 7 5-m)] compared with a RSA with one change of direction [10 7 (2 7 15-m)], and the relationship of the RSM and RSA with Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) and jump performances [squat jump (SJ) and counter-movement-jump (CMJ)]. Thirty-six (male, n = 14, female n = 22) young basketball players (age 16.0 \ub1 0.9 yrs) performed the RSM, RSA, Yo-Yo IR1, SJ, and CMJ, and were re-tested only for RSM and RSA after 1 week. The absolute error of reliability (standard error of the measurement) was lower than 0.212 and 0.617-s for the time variables of the RSA and RSM test, respectively. Performance in the RSA and RSM test significantly correlated with CMJ and SJ. The best time, worst time, and total time of the RSA and RSM test were negatively correlated with Yo-Yo IR1 distance. Based on these findings, consistent with previously published studies, it was concluded that the novel RSM test was valid and reliable

Repeated Sprint Ability in Young Basketball Players (Part 2): The Chronic Effects of Multidirection and of One Change of Direction Are Comparable in Terms of Physiological and Performance Responses

The aim of this study was to examine the effects of a 5-week training program, consisting of repeated 30-m sprints, on two repeated sprint ability (RSA) test formats: one with one change of direction (RSA) and the other with multiple changes of direction (RSM). Thirty-six young male and female basketball players (age 16.1 \ub1 0.9 years), divided into two experimental groups, were tested for RSA, RSM, squat jump, counter-movement jump, and the Yo-Yo Intermittent Recovery-Level-1 (Yo-Yo IR1) test, before and after a 4-week training program and 1 week of tapering. One group performed 30-m sprints with one change of direction (RSA group, RSAG), whereas the other group performed multidirectional 30-m sprints (RSM group, RSMG). Both groups improved in all scores in the post-intervention measurements (P < 0.05), except for the fatigue index in the RSM test. However, when comparing the two groups, similar effects were found for almost all parameters of the tests applied, except for RPE in the RSA test, which had a greater decrease in the RSAG (from 8.7 to 5.9) than in the RSMG (from 8.5 to 6.6, P = 0.021). We can conclude that repeated 30-m sprints, either with one change of direction or multidirectional, induce similar physiological and performance responses in young basketball players, but have a different psycho-physiological impact

Inter-limb asymmetries in swimming and their impact on performance: evidence from a scoping review

The objectives of the present review were to: (a) map the studies analyzing bilateral asymmetries in specific (in-water tests) and non-specific (dry-land tests) swimming contexts and (b) investigate the effects of inter-limb asymmetries on swimming performance. Searches were systematically conducted on four databases. Out of 768 studies examined, 60 were eligible for the final selection (https://osf.io/46gya). Twenty-eight studies analyzed asymmetries during in-water tests, with asymmetry values ranging from 2.7 to 60.0%, and most studies (n = 18) reported significant between-limb differences (p 0.05). Eight studies measured asymmetries in both contexts and reported asymmetry values from -24.1 to 17.4%, with four studies finding significant differences between body sides (p < 0.05). Seven of the 60 studies selected investigated the relationship between asymmetries and swimming performance, with five reporting no meaningful associations with swimming performance. In conclusion, significant asymmetries in swimming are more evident during in-water than during dry-land tests. In addition, the few studies investigating asymmetries' influence on swimming performance reported that asymmetries rarely impact swimming performance

Relationship of aerobic and neuromuscular indexes with specific actions in judo

Objective. - The aim of this study was to verify the relationship of aerobic and neuromuscular indexes with specific situations in judo. Method. - Eighteen male judokas took part in the study. The following assessments were performed: vertical jump (CMJ) on a force platform; Special Judo Fitness Test (SJFT) to obtain the number of throws and percentage of the maximal heart rate (%HRmax) one minute after the test; match simulation to obtain the peak blood lactate (LACmax) and the percentage of the blood lactate removal (BLR); incremental test to obtain the velocity at the anaerobic threshold (vAT) and peak velocity (PV) reached in the test. Results. - A significant correlation was observed between the number of throws in the SJFT, the vAT (r = 0.60; P &lt; 0.01), PV (r = 0.70; P &lt; 0.01) and CMJ (r = 0.74; P &lt; 0.01). A significant inverse correlation was found between the LACmax and vAT (r = -0.59; P = 0.01). Conclusions. - It can be concluded that the performance in the SJFT was determined by the aerobic capacity and power and the muscle power. Athletes with greater aerobic ability (vAT) presented lower blood lactate accumulation after the match. (c) 2011 Elsevier Masson SAS. All rights reserved

Single-versus multi-joint isometric protocols to induce a post-activation potentiation effect on squat jump performance

Purpose. The objective of the study was to analyse the effects of post-activation potentiation induced by single- and multijoint maximal voluntary isometric contractions (MVIC) on squat jump performance. Methods. Overall, 13 resistance-training males volunteered to participate in the study. Isometric knee extension exercise was chosen to represent single-joint MVIC (MVIC_SJ) and isometric squat to represent multi-joint MVIC (MVIC_MJ). Four experimental protocols were implemented in a randomized order on different days as follows: P1: squat jump performed before and 3 minutes after MVIC_MJ; P2: squat jump performed before and 7 minutes after MVIC_MJ; P3: squat jump performed before and 3 minutes after MVIC_SJ; P4: squat jump performed before and 7 minutes after MVIC_SJ. Jump height, mean power output, peak power output, net impulse, and electromyographic activity of lower limbs were analysed in squat jump before and after the interventions. Results. ANOVA showed that peak power output increased in P1 (p = 0.04). No difference was found for electromyographic activity in any of the protocols. Conclusions. We concluded that MVIC_MJ performed 3 minutes before the main task (P1) was more effective than MVIC_SJ in optimizing squat jump performance and that the changes in performance were unrelated to muscle activatio

Concurrent validity and technological error-based reliability of a novel device for velocity-based training

The aim of this study was to verify the concurrent validity and the biological error-free reliability of a novel low-cost commercial encoder (Ergonauta I). Validity protocol involved comparisons with a custom system and other encoder commercially available (Vitruve). Reliability protocols involved inter devices and inter unit comparisons. No participants were recruited, and reliability assessments were performed in a Smith Machine by bar free fall tests. Our results showed a significant bias for mean velocity (MV) estimated by both encoders only in one of the four conditions investigated (bias=0.05 m/s). Regarding sensitivity, the smallest detectable change suggests only values higher than 0.03 m/s must to be considered as real changes in performance, when monitoring MV and mean propulsive velocity (MPV) through Ergonauta I and Vitruve. Between-days intra-device reliability showed Ergonauta I remains highly reliable after one week for most assessments, whereas slightly less sensitive for peak velocity and peak power output

Effects of four weeks of repeated sprint training on physiological indices in futsal players,Efeito de quatro semanas de treinamento de sprints repetidos sobre {\'i}ndices fisiol{\'o}gicos em atletas de futsal

The aim of this study was to investigate the effects of short repeated-sprint ability (RSA) training on the neuromuscular and physiological indices in U17 futsal players during the competitive period. Fourteen players were divided into two groups: intervention group (n = 8) and control group (n = 6). Both groups performed a repeated maximal sprint test (40-m MST), intermittent shuttle-running test (Carminatti’s test) and vertical jumps before and after the training period. The intervention group was submitted to an additional four-week repeated sprints program, twice a week, while the control group maintained their normal training routine. There was no significant interaction between time and groups for all variables analysed (p > 0.05). However, a significant main effect was observed for time (p < 0.01) indicating an increase on speed at heart rate deflection point (VHRDP) and the continuous jump performance while the peak lactate (40m-LACpeak) and sprint decrement decreased after training, in both groups. Still, based on effect sizes (ES) the greater changes with practical relevance were verified for intervention group in important variables such as peak velocity (ES = 0,71), VHRDP (ES = 0,83) and 40m-LACpeak (ES = 1,00). This study showed that RSA-based and normal training routine are equally effective in producing changes in the analysed variables during a short period of intervention. However, the effect size suggests that four weeks of RSA training would be a minimum time that could induce the first changes of futsal player’s physical fitness