Jumping-based asymmetries are negatively associated with jump, change of direction, and repeated sprint performance, but not linear speed, in adolescent handball athletes

The aim of the present study was to determine the association of multi-directional jumping asymmetries with measures of physical performance. Forty-two youth handball athletes (age: 16.0 ± 1.3 years; body height: 174.11 ± 7.3 cm; body mass: 70.49 ± 13.3 kg) performed a mid-season fitness test battery consisting of single leg countermovement, lateral and broad jump tests, two change of direction speed (CODS) tests, an 8 x 10 m repeated sprint test, and a 20 m sprint. The Kappa coefficient showed only ‘slight’ levels of agreement (K range = -0.05 to 0.15), indicating that asymmetries rarely favoured the same side during each of the jump tests. The single leg countermovement jump showed significantly (p = 0.006) larger asymmetries (11.2 ± 8.4) than the broad jump (6.4 ± 4.6) and significant correlations were present between jumping asymmetries and jump (r = -0.32 to -0.52), CODS (r = 0.31 to 0.32) and repeated sprint (r = 0.35 to 0.40) performance. The findings of the present study highlight the independent nature of jumping asymmetries and associations with measures of physical performance. Practitioners are encouraged to use multiple tests to detect existing side differences and consider appropriate training interventions for the reduction of inter-limb asymmetries

Acute and chronic effects of competition on ankle dorsiflexion ROM in professional football players.

The aim of this study was to investigate the acute (a football match) and chronic (a whole season) effects of competition on ankle dorsiflexion ROM in professional football players. Forty football players participated in this study. Ankle dorsiflexion ROM was recorded to examine acute (pre-match, immediately post-match and 48 h post-match) and chronic (pre-season, mid-season and post-season) effects of competitive football. In addition, it was found that players had restricted mobility measures on ankle dorsiflexion as >2 cm change between baseline measures (pre-match and pre-season). The training load of all played matches was estimated using a global positioning system (GPS) and RPE. Pre-season ankle dorsiflexion ROM was greater compared to mid-season (8.1% in the dominant, and 9.6% in the non-dominant leg) and post-season (13.8% in the dominant, and 12.5% in the non-dominant leg). In addition, around 30% of all players showed restricted ankle dorsiflexion ROM values in post-season compared with pre-season. Related to acute effects, ankle dorsiflexion ROM increased after a match (5.8%) in the dominant ankle, and this value decreased (2.65%) 48 h post-match when post-match measurements in both dominant and non-dominant ankles were compared. The progressive decrease in ankle dorsiflexion ROM throughout a season can be an indicator of increased risk of injury and may be reinforce the need of prevention actions such as stretching exercises and eccentric strength training in professional football players. In addition, these findings suggest to implement specific recovery strategies aiming at minimizing alteration in ankle dorsiflexion ROM 48 h post-match.pre-print594 K

Effects of an integrative neuromuscular training protocol vs. FIFA 11+ on sprint, change of direction performance and inter-limb asymmetries in young soccer players

his study compared the effects of integrative neuromuscular training (INT) versus FIFA 11+ protocols on sprint, change of direction performance and inter-limb asymmetries. Thirty young (U-11) male soccer players (age: 11.2 ± 0.7 years; height: 145.6 ± 6.8 cm; body mass: 72.5 ± 3.0 kg) were randomly assigned to each training group, which consisted of two sessions/week for a period of 6-weeks. The INT consisted of play-based tasks designed according to structured training principles, whereas the FIFA 11+ followed standard procedures. Before and after the intervention, 0-20 sprint time and double 180° change of direction test were measured from which change of direction deficit and inter-limb asymmetries were also computed. Significant improvements were found in double 180° change of direction test and deficit for both legs in both groups (all p < 0.01). A significant decrease was observed in 0-20 sprint time (p < 0.05), and inter-limb asymmetries for FIFA 11+ group. A significant group-by-time effect, which favored the FIFA 11+ group, was observed on double 180° change of direction in right leg (F = 15.08, p < 0.01, η2p = 0.35), but also in change of direction deficit in right (F = 214.19, p < 0.01, η2p = 0.88), and left legs (F = 126.79, p < 0.01, η2p = 0.82). These findings suggest youth soccer practitioners should select the FIFA 11+ program to improve inter-limb asymmetries and 0-20 sprint time, and that both training methods are suitable to improve 180° change of direction performance

Effects of 8-weeks of isoinertial vs. cable-resistance training on motor skills performance and interlimb asymmetries

Two training interventions conducted on youth handball athletes

The Relationship Between Performance and Asymmetries in Different Multidirectional Sprint Tests in Soccer Players

Practitioners usually include change of direction (COD) and linear speed measurements in the testing batteries of soccer players; however, despite being a commonly occurring action, curve sprint (CS) ability is rarely assessed in soccer. The aims of this study were to analyze the association between linear sprint, CS, and COD speed performances, and compare the association and direction of asymmetries between these skills. Thirty-three male soccer players performed linear sprint (17 m), CS (17 m), and COD-90º speed tests (COD [8.5 + 8.5 m]). Our main findings were (a) a large relationship between linear and multidirectional tasks (COD-90º and CS tests) (r = from 0.6 to 0.64, p 0.05) between COD and CS asymmetries, with opposing directional dominance in ~70% of players (e.g., curve left and COD right dominance). These results indicate that performance in linear sprints is strongly related to performance in multidirectional trajectories, whereas CS and COD-90º seem to be more independent actions. Additionally, the direction of asymmetry or dominance is generally opposite between the non-linear tasks measured

Acute effects of dynamic versus foam rolling warm-up strategies on physical performance in elite tennis players.

To date, there is a lack of information about the optimal conditions of the warm-up to lead to a better performance in elite tennis players. The aim of this study was to compare the effects of two different warm-up protocols (dynamic vs. self-myofascial release with foam rolling) on neuromuscular variables associated with physical determinants of tennis performance. Using a crossover randomised experimental design, eleven professional men tennis players (20.6 ± 3.5 years) performed either a dynamic warm-up (DWU) or a selfmyofascial release with foam rolling (SMFR) protocol. DWU consisted of 8 min of dynamic exercises at increasing intensity and SMFR consisted of 8 min of rolling on each lower extremity unilaterally. Just before (baseline) and after completing warm-up protocols, players performed a countermovement jump (CMJ), the 5-0-5 agility test, a 10-m sprint test and the Straight Leg Raise and Thomas tests to assess range of motion. Compared to baseline, the DWU was more effective to reduce the time in the 5-0-5 test than SMFR (-2.23 vs. 0.44%, respectively, p = 0.042, ηp2 = 0.19). However, both warm-up protocols similarly affected CMJ (2.32 vs. 0.61%, p = 0.373, ηp2 = 0.04) and 10-m sprint time changes (-1.26 vs. 1.03%, p = 0.124, ηp2 = 0.11). Changes in range of motion tests were also similar with both protocols (p = 0.448–1.000, ηp2 = 0.00–0.02). Overall, both DWU and SMFR were effective to prepare well-trained tennis players for highly demanding neuromuscular actions. However, DWU offered a better preparation for performing change of direction and sprint actions, and hence, in high-performance tennis players, the warm-up should include dynamic exercises.post-print402 K

Effects of different inertial load settings on power output using a flywheel leg curl exercise and its inter-session reliability

This study aimed to analyze the influence of the inertial load on both concentric and eccentric power output production during the flywheel leg curl exercise, and to assess the reliability of power output variables. Sixteen participants (8 males, 8 females) attended 4 testing sessions. During testing, participants performed one set of eight repetitions using a specific inertial load (0.083, 0.132, 0.182, 0.266 and 0.350 kg·m2) with a flywheel leg curl exercise. Concentric (CON) power, eccentric (ECC) power and the ECC/CON ratio were analyzed. The reliability analysis between sessions was performed. A significant interaction of inertia load x gender was found in CON power (p < 0.001) and in ECC power (p = 0.004), but not in the ECC/CON ratio (p = 0.731). A significant with-in (inertia loads) effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.096). CON power showed very high reliability scores, ECC power showed high to very high reliability scores, while the ECC/CON ratio ranged from poor to moderate. A significant between gender effect was found in CON power (p < 0.001) and in ECC power (p < 0.001), but not in the ECC/CON ratio (p = 0.752). This study is the first to report that power output in the flywheel leg curl exercise is altered by the inertia load used, as well as power output is different according to gender. CON and ECC power output presents high to very high reliability scores, and the ECC/CON ratio should not be used instead. These results can have important practical implications for testing and training prescription in sports

Validity and Reliability of the V-Cut Dribbling Test in Young Basketball Players

Purpose: Change of direction while dribbling appears to be of interest for on-court performance in basketball. The study aim was to assess the validity and reliability of the V-cut dribbling test (VcutBk) in young basketball players. Methods: Ninety-two young basketball players from 8 to 21 years old (74% male) were classified in relation to peak height velocity (PHV) offset. To examine validity and test–retest reliability, VcutBk was performed in 2 identical sessions separated by 1 week. Participants also performed the V-cut test and linear sprint test with and without dribbling to analyze correlations between tests in different somatic maturity stages. Results: The relationships of the VcutBk with the other tests and skill-time-related deficits were interpreted from large (r > .51) to very large (r > .71). The comparisons between pre-PHV and post-PHV groups of basketball players showed significant and large effect in the VcutBk (d = 2.04; mean difference = 2.59; 95% CI, 1.86 to 3.32). Also, significant main effects when comparing PHV groups were reported in all skill-time-related deficits (P < .001, η 2 p = . 13 − .28 , moderate to large effect size). Test–retest reliability and signal-to-noise ratio analysis did not show substantial between-trials differences in VcutBk. Reliability scores showed high intraclass correlation coefficient (.95) and low coefficient of variation (0.23%). Conclusions: The VcutBk seems to be a valid and reliable test to assess change of direction while dribbling. VcutBk performance and skill-time-related deficits seem to be sensitive to somatic maturity. Basketball coaches should consider the VcutBk to assess young basketball players

Effects of maturation on lower limb neuromuscular asymmetries in elite youth tennis players

Neuromuscular asymmetries have been previously associated with reduced performance. Similarly, maturation has shown that youth athletes may experience a loss of motor control, which could also lead to compromised physical performance. The present study aimed to evaluate and quantify the level of asymmetry among chronological and maturational groups. Forty-one youth tennis players performed the single leg countermovement jump (SLCMJ), star excursion balance test (SEBT) and a change of direction speed (CODS) test. Differences were found between the strongest and weakest limbs across all tests (p 0.001), and also for SEBT in the posteromedial direction (p = 0.02), SEBT composite score (p 0.01) in maturation groups, and for SEBT posterolateral direction (p = 0.03) and SEBT composite score (p = 0.01) in chronological groups. The SLCMJ showed the largest inter-limb asymmetries for the circa peak height velocity (PHV) group (19.31 ± 12.19%) and under-14 (U14) group (17.55 ± 9.90%). Chronological and maturation groups followed similar trends for inter-limb asymmetries, but the biological index showed larger asymmetry scores in the jumping test at PHV compared to that found in the chronological group (U14). These results show that inter-limb differences may be heightened during PHV. Practitioners can use this information to inform the decision-making process when prescribing training interventions in youth tennis players