Vertical jump kinetic parameters on sand and rigid surfaces in young female volleyball players with a combined background in indoor and beach volleyball

Little is known about the differences in vertical jump biomechanics executed on rigid (RJS) and sand (SJS) surfaces in female indoor and beach volleyball players. Eleven young female beach volleyball players with a combined indoor and beach volleyball sport background performed squat jumps, countermovement jumps with and without an arm swing, and drop jumps from 40 cm on a RJS (force plate) and SJS (sand pit attached to the force plate). The results of the 2 (surface) × 4 (vertical jump test) repeated-measure ANOVA revealed a significant (p 0.05), was observed for the other examined biomechanical parameters. The only significant (p < 0.05) jump height gain difference between RJS and SJS was observed for the utilization of the stretch-shortening cycle, which was higher in SJS (15.4%) compared to RJS (7.5%). In conclusion, as the testing was conducted during the beach volleyball competitive season, the examined female players showed adaptations relating the effective utilization of the pre-stretch and enhanced stability during the execution of the vertical jump tests on a SJS compared to RJS

Reliability of a Pendulum Apparatus for the Execution of Plyometric Rebound Exercises and the Comparison of Their Biomechanical Parameters with Load-Matching Vertical Drop Jumps

The inability to control the body center of mass (BCM) initial conditions, when executing plyometric exercises, comprises a restrictive factor to accurately compare jumps executed vertically and horizontally. The purpose of the study was to present a methodological approach for the examination of BCM initial conditions during vertical drop jumps (VDJ) and plyometric rebound jumps performed with a pendulum swing (HPRJ). A system consisting of two force plates was used for the evaluation of VDJ. A bifilar pendulum, equipped with a goniometer and accelerometer, was constructed for the evaluation of the HPRJ. Kinematic parameters from both jump modalities were obtained by means of videography (100 Hz). Thirty-eight physically active young males executed VDJ and HPRJ with identical BCM kinetic energy at the instant of impact (KEI). Results revealed that participants produced higher power and lower force outputs at HPRJ (p < 0.01). The rate of force development was larger in VDJ, while hip movement was less in HPRJ. The use of the presented methodology provided the means to reliably determine the exact BCM release height during the execution of the examined jumps. This provided an accurate determination of the amount of KEI, being the main parameter of calculating load during plyometric exercise

Sport specificity background affects the principal component structure of vertical squat jump performance of young adult female athletes

Purpose: Long-term training specificity is thought to alter performance in tests evaluating strength and power production capability. The aim of the present study was to provide additional information to the limited existing knowledge concerning the possible differences of the force/time profile of squat jumping among different groups of young female athletes. Methods: One hundred and seventy-three adult women (20.1 ± 2.8 years, 1.71 ± 0.09 m, 65.6 ± 10.3 kg, mean ± SD for age, height, and mass, respectively) engaged in track and field (TF), volleyball (VO), handball (HA), basketball (BA), and physical education students (PE) executed maximal squat jumps (SQJ) on a force plate. Pearson's correlation was used to identify the relationship between SQJ performance, the anthropometric characteristics and the biomechanical parameters. Differences concerning the biomechanical parameters among groups were investigated with analysis of variance, while the force- (FPD) or time- (TPD) dependency of SQJ execution was examined using principal components analysis (PCA). Results: SQJ was unrelated to body height but significantly correlated with body mass (r = −0.26, p = 0.001). TF jumped higher and produced larger peak body power output compared to all the other groups (p < 0.05). All athletes were superior to PE since they performed the SQJ with a longer (p < 0.05) vertical body center of mass trajectory during the propulsion phase. PCA results revealed that TF significantly differentiated than the other groups by relying on FPD. Conclusion: Various different profiles of FPD and TPD were detected due to different sporting background in young female athletes. Since TF superiority in SQJ was relied on the larger power production and a greater FPD, female indoor team sport athletes are suggested to execute jumping exercises adopting the jumping strategies utilized by TF

Vertical Jump Kinetic Parameters on Sand and Rigid Surfaces in Young Female Volleyball Players with a Combined Background in Indoor and Beach Volleyball

Little is known about the differences in vertical jump biomechanics executed on rigid (RJS) and sand (SJS) surfaces in female indoor and beach volleyball players. Eleven young female beach volleyball players with a combined indoor and beach volleyball sport background performed squat jumps, countermovement jumps with and without an arm swing, and drop jumps from 40 cm on a RJS (force plate) and SJS (sand pit attached to the force plate). The results of the 2 (surface) × 4 (vertical jump test) repeated-measure ANOVA revealed a significant (p p p > 0.05), was observed for the other examined biomechanical parameters. The only significant (p < 0.05) jump height gain difference between RJS and SJS was observed for the utilization of the stretch-shortening cycle, which was higher in SJS (15.4%) compared to RJS (7.5%). In conclusion, as the testing was conducted during the beach volleyball competitive season, the examined female players showed adaptations relating the effective utilization of the pre-stretch and enhanced stability during the execution of the vertical jump tests on a SJS compared to RJS

Relationship of Vertical Jump Performance and Ankle Joint Range of Motion: Effect of Knee Joint Angle and Handedness in Young Adult Handball Players

The purpose of the study is to examine the effect of the ankle joint range of motion (ROM) on the vertical jump (VJ) performance of adult handball players. The active (ACT) and passive (PAS) ankle joint ROM of 12 male members of the U21 National Handball Team with the knee joint at 0&deg;, 40&deg;, and 90&deg; flexion (0&deg; = fully extended knee) was evaluated using a video analysis measuring method. Participants also performed maximum VJ with (CMJ) and without (SQJ) countermovement, as well as with (AS) and without (NAS) an arm swing. Statistical analyses included 2 &times; 2 &times; 3 MANOVA, 2 &times; 2 repeated measures ANOVA, and Pearson&rsquo;s correlation. Results reveal that PAS-ROM was larger (p &lt; 0.05) in all knee joint flexion angles. ROM was smaller (p &lt; 0.05) by approximately 10&deg; at 0&deg; compared to 90&deg; knee flexion. No lateral effects on ROM due to the handedness of the players were observed. AS and CM resulted in increased jump height (p &lt; 0.05). Finally, ACT-ROM when the knee joint was flexed at 40&deg; was highly correlated (r &ge; 0.66, p &lt; 0.05) with VJ performance except for CMJ-AS. In conclusion, the differences in the bi-articular gastrocnemius muscle flexibility due to the alteration of the angular position of the examined joints affected the ability to generate impulse during the VJ tests

Temporal analysis of elite men’s discus throwing technique

The purpose of this study was to investigate the relationship between the duration of the throw and the official throwing distance in a group of elite male discus throwers. The time analysis of the technique phases (i.e. preparation, entry, flight, transition, delivery, release) of the participants in a top international athletics competition was used in order to conduct the study. Data were retrieved after recording seven right-handed throwers (age: 28.8 ± 4.1 years, body height: 1.94 ± 0.09 m, body mass: 119.4 ± 11.6 kg) with a Casio EX-FX1 (Casio Computer Co. Ltd) digital video camera (sampling frequency: 300fps) and analyzing the captured throws with the V1 Home 2.02.54 software (Interactive Frontiers Inc.). The relationships among the duration of the technique phases of the throw and the official throwing distance were examined with Pearson Correlation Analysis using the SPSS 10.0.1 software (SPSS Inc.). Results revealed that no significant correlation (p > 0.05) existed among the average official throwing distance (63.04 ± 6.09 m) and the duration of the discus throw or the duration of each technique phase. The temporal and correlation analyses were in agreement with previous studies. The dominant style of release was the release with no support on the ground. The majority of the throwers spent a larger percentage of the delivery turn (transition, delivery and release phases) being in single than in double support. It was noted that a short duration of the transition phase, combined with lower values of the ratio of the time spent for the starting turn compared to the time spent for the delivery turn might be favorable regarding the achievement of a larger throwing distance