Sensory equipment for monitoring and assessing the jumping ability of volleyball players.

Purpose: The objective of this research was to develop a sensor device to control and evaluate the jumping ability of elite volleyball athletes and to test its efficacy in a pedagogical experiment. Methods: The study involved determining the pulsometric and respiratory parameters during test loads, indicative of the endurance and speed-strength aspects essential for volleyball performance. Additionally, the necessity for post-training and post-competition jump performance restoration via short-term relaxation exercises was identified. Results: Through the developed computer program, a method for storing maximal vertical jumps in computer memory was established. Furthermore, a technique was developed to determine the functional significance of maximum vertical jump performance among elite volleyball players. Notably, participants in the experimental group, who performed specialized exercises developed within the experimental framework, exhibited discernible progressive improvements compared to the control group participants. Before the experiment, the maximum number of jumps in the experimental group was 29.2 ± 2.73, with a jump time of 31.7 ± 3.08. Conclusions: The equipment developed for monitoring and assessing volleyball players' jumping ability has proven effective, warranting its incorporation into training regimens.

Quantifying and analysing the angular momentum in volleyball jump serve during the aerial phase: relationship to arm swing speed.

Background: In volleyball, the jump serve is a crucial and commonly used serving technique. Nonetheless, the angular momentum developed during the jump serve remains unexplored. The objectives of the current study were to determine the angular momentum manifesting during the airborne phase of the jump serve and to analyse the correlations between the angular momentum variables and arm swing speed. Methods: Three-dimensional coordinate data were obtained during the jump serves of 17 professional male volleyball players. Correlation and linear regression analyses were used to identify the angular momentum variables linked to the arm swing speed at ball impact (BI). Results: The arm swing speed at BI exhibited significant correlations with the peak angular momentum of the attack arm (r = 0.551, p = 0.024), non-attack arm (r = 0.608, p = 0.011), non-attack leg (r = -0.516, p = 0.034), forearm (r = 0.527, p = 0.032), and hand (r = 0.824, p < 0.001). A stepwise regression model (R2 = 0.35, p = 0.043) predicted arm swing speed based on the peak angular momentum of the non-attack leg, forearm, and hand. Conclusions: The study results suggest that during the arm-acceleration phase, (1) increasing angular momentum with the non-attack leg helps maintain aerial body balance, thereby enhancing arm swing execution, and (2) controlling the magnitude and timing of the force exerted by the elbow and wrist is crucial for effectively transmitting angular momentum, contributing to an increase in arm swing speed.

The Functional Organization of Corticomotor Neurons Within the Motor Cortex Differs Among Basketball and Volleyball Athletes With Patellar Tendinopathy Compared to Asymptomatic Controls.

Patellar tendinopathy (PT) typically affects jumping-sport athletes with functional impairments frequently observed. Alterations to the functional organization of corticomotor neurons within the motor cortex that project to working muscles are evident in some musculoskeletal conditions and linked to functional impairments. We aimed to determine if functional organization of corticomotor neuron projections differs between athletes with PT and asymptomatic controls, and if organization is associated with neuromuscular control. We used a cross-sectional design, and the setting was Monash Biomedical Imaging. Basketball and volleyball athletes with (n = 8) and without PT (n = 8) completed knee extension and ankle dorsiflexion force matching tasks while undergoing fMRI. We determined functional organization via identification of the location of peak corticomotor neuron activation during respective tasks (expressed in X, Y, and Z coordinates) and calculated force matching accuracy for both tasks to quantify neuromuscular control. We observed significant interactions between group and coordinate plane for functional organization of corticomotor projections to knee extensors (p < 0.001) and ankle dorsiflexors (p = 0.016). Compared to controls, PT group peak corticomotor activation during the knee extension task was 9.6 mm medial (p < 0.001) and 5.2 mm posterior (p = 0.036), and during the ankle dorsiflexion task 8.2 mm inferior (p = 0.024). In the PT group, more posterior Y coordinate peak activation location during the knee extension task was associated with greater task accuracy (r = 0.749, p = 0.034). Functional organization of corticomotor neurons differed in jumping athletes with PT compared to controls. Links between functional organization and neuromuscular control in the PT group suggest organizational differences may be relevant to knee extension neuromuscular control preservation.

The effects of fatigue on the relationship between ankle angle at initial contact and the knee and hip joints in landing: Assessing the risk of ACL injury.

BACKGROUND: Anterior cruciate ligament (ACL) injuries may correlate with lower limb angles and biomechanical factors in both dominant and non-dominant legs at initial contact (IC) post-landing. This study aims to investigate the correlation between ankle angles in three axes at IC and knee and hip joint angles during post-spike landings in professional volleyball players, both pre- and post-fatigue induction. RESEARCH QUESTION: To what extent does fatigue influence lower limb joint angles, and what is the relationship between ankle joint angles and hip and knee angles at IC during the landing phase following a volleyball spike? METHODS: Under conditions involving the peripheral fatiguing protocol, the lower limb joint angles at IC following post-spike landings were measured in 28 professional male volleyball players aged between 19 and 28 years, who executed the Bosco fatigue protocol both before and after inducing fatigue. A paired t-test was utilized to compare the joint angles pre- and post-fatigue in both dominant and non-dominant legs. Furthermore, Pearson's correlation test was conducted to explore the relationship between ankle angles at IC and the corresponding knee and hip joint angles. RESULTS: The findings of the study revealed that fatigue significantly increased hip external rotation and decreased knee joint flexion and external rotation in both the dominant and non-dominant legs (p < 0.05). Additionally, correlation analysis demonstrated that the ankle joint's positioning in the frontal and horizontal planes was significantly associated with hip flexion and external rotation at the IC, as well as with knee flexion and rotation (0.40 < r < 0.80). CONCLUSION: Fatigue increased hip external rotation and ankle internal rotation, weakening the correlation between these joints while strengthening the ankle-knee relationship, indicating a reduced hip control in jumps. This suggests a heightened ACL injury risk in the dominant leg due to the weakened ankle-hip connection, contrasting with the non-dominant leg.

Physiological and Performance Adaptations to Varying Rest Distributions During Short Sprint Interval Training Trials in Female Volleyball Players: A Comparative Analysis of Interindividual Variability.

PURPOSE: This study aimed to examine the impact of different rest periods between short sprint interval training (SSIT) trials on the physiological and performance adaptations of female volleyball players. METHODS: Twenty-four trained college athletes volunteered to participate in this study and were randomly assigned to 3 SSIT groups with different work-to-rest ratios (1:2 [5-s run:10-s rest], 1:4 [5-s run:20-s rest], and 1:6 [5-s work:30-s rest]). Before and after 6-week training, physiological parameters (maximum oxygen uptake, first and second ventilatory thresholds, and peak and mean power output) and physical performance measures (ie, countermovement vertical jump, 10-m sprint, and T-test change-of-direction speed) were evaluated. RESULTS: After the training period, all groups improved (P = .001) their sport-related performance and physiological parameters, ranging from moderate to very large effect sizes. Comparative analysis of the magnitude of training effects indicated that the 1:6 SSIT group had in a significantly greater change in countermovement vertical jump (P = .007), 10-m sprint (P = .014), peak power output (P = .019), and mean power output (P = .05) compared with 1:2 SSIT group. By contrast, the 1:2 SSIT group demonstrated significantly (P = .022) greater changes in maximum oxygen uptake than the 1:6 SSIT group. However, the change-of-direction speed and changes in first and second ventilatory thresholds were the same among the groups (P > .05). CONCLUSIONS: When performing SSIT, longer rest intervals are suitable for physical and anaerobic performance, and shorter rest periods are appropriate for enhancing the cardiorespiratory fitness of female volleyball players' performance.

Chronobiological Insights in Plyometric Jump Training: Optimizing Sport-Performance Adaptations for Volleyball Players.

PURPOSE: The objective of this study was to investigate the effects of morning versus evening plyometric training (PT) on performance adaptations in male volleyball players. METHODS: A total of 30 collegiate national-level young male volleyball players (age = 21.9 [2.1]; height = 186 [4.1]; body mass = 82.4 [4.6]) were randomly divided into 3 groups: morning PT (MPT), evening PT (EPT), and an active control group, each group consisting of 10 subjects. The players engaged in PT sessions twice weekly for a period of 6 weeks. The evaluation of biomotor abilities such as countermovement vertical jump, standing long jump, spike jump, block jump, 10-m sprint, T-test, sit and reach, and Y-balance test took place in the morning and evening before and after the intervention. RESULTS: Both the MPT and EPT groups indicated significant (P < .05) improvements in all biomotor abilities from pretraining to posttraining during both the morning and evening testing sessions. Furthermore, the MPT group displayed greater adaptive responses in the vertical jump (P = .001), standing long jump (P = .023), and Y-balance test (P ≤ .01) compared to the EPT group. Time-of-day fluctuations were the same between the MPT and EPT groups at the pretest. Conversely, EPT demonstrated significantly more daytime variations than MPT in the jump, sprint, and balance tests at postintervention (P < .05). CONCLUSION: Engaging in PT at specific times of the day has a significant impact on biomotor ability adaptations, with a focus on morning being more favorable than the evening for achieving greater gains in jump and balance performance of volleyball players.

Effect of ball positions on trunk, hip, knee, and ankle joint kinematics and kinetics during a spike jump in volleyball.

BACKGROUND: Anterior cruciate ligament injuries are serious conditions encountered in volleyball players and occur frequently during spike jump landings. During spike jumps, the lower limb kinematics and kinetics during landing may be altered in relation to the ball position. RESEARCH QUESTION: Does the ball position have an effect on lower-limb kinematics and kinetics during spike jumps? METHODS: We measured the lower limb kinematics and kinetics of 20 healthy female college volleyball athletes during a spike jump using a three-dimensional motion analysis system. The ball positions were set to normal, dominant, and non-dominant positions. A repeated analysis of variance was used to compare the lower limb kinematics and kinetics at the initial contact and the maximum knee flexion during jump landing. Additionally, statistical parametric mapping analysis was used to analyze changes over time during the spike jumps. RESULTS: At the initial contact of the spike jump landing, the knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment when the ball was set at the non-dominant position increased compared to those at the dominant position. Statistical parametric mapping analysis showed no significant change in knee valgus angle and moment of jump landing. CONCLUSION: Knee valgus angle, trunk lateral bending angle, and maximum knee valgus moment increased with the non-dominant position; furthermore, the risk of ACL injury may also be increased. SIGNIFICANCE: The posture at ball impact may influence the landing kinematics and kinetics. Therefore, it is necessary to pay close attention to movements during and prior to landing.

Volleyball training improves working memory in children aged 7 to 12 years old: an fNIRS study.

This study aimed to investigate the effect of a 12-wk extracurricular volleyball training on working memory from both behavioral and cerebral aspects. A total of 80 children were randomized assigned to (i) the experimental group, who engaged in extracurricular volleyball training for 60 min, thrice a week for 12 wk, and (ii) the control group, who maintained their regular daily routine. Working memory was evaluated in both groups using the N-back task before and after the intervention. Furthermore, functional near-infrared spectroscopy was employed to monitor the level of oxygenated hemoglobin in the prefrontal cortex. The experimental group performed better in the behavioral task than the control group, as evidenced by a shorter response time and a higher correct rate. The functional near-infrared spectroscopy results suggested that the activation of the left dorsolateral prefrontal cortex was significantly higher in the experimental group than in the control group. In addition, correlation analyses showed that the enhancement of left dorsolateral prefrontal cortex activation was significantly correlated with decreasing response time and improving response accuracy in the N-back task. These findings suggest that the left dorsolateral prefrontal cortex is likely the neural substrate for improved working memory performance elicited by 12-wk open skill exercise.

How reliable are lower limb biomechanical evaluations during volleyball-specific jump-landing tasks?

BACKGROUND: Biomechanical evaluations of sport-specific jump-landing tasks may provide a more ecologically valid interpretation compared to generic jump-landing tasks. For accurate interpretation of longitudinal research, it is essential to understand the reliability of biomechanical parameters of sport-specific jump-landing tasks. RESEARCH QUESTION: How reliable are hip, knee and ankle joint angles and moment curves during two volleyball-specific jump-landing tasks and is this comparable with the reliability of a generic jump-landing task? METHODS: Three-dimensional (3D) biomechanical analyses of 27 male volleyball players were performed in two sessions separated by one week. Test-retest reliability was analyzed by calculating integrated as well as 1D intraclass correlation coefficient (ICC) and integrated standard error of measurement (SEM) for hip, knee and ankle angles and moments during a spike and block jump (volleyball-specific tasks), and during a drop vertical jump (generic task). RESULTS: Reliability of joint angles of volleyball-specific and generic jump-landing tasks are similar with excellent-to-good integrated ICC for hip, knee and ankle flexion/extension (ICC= 0.61-0.89) and hip and knee abduction/adduction (ICC=0.61-0.78) but fair-to-poor ICC for ankle abduction/adduction (ICC=0.28-0.52) and hip, knee and ankle internal/external rotation (ICC=0.29-0.53). Reliability of hip, knee and ankle joint moments was good-to excellent (ICC= 0.62-0.86) except for hip flexion moment during spike jump and drop vertical jump (ICC=0.43-0.47) and knee flexion moment during both volleyball-specific tasks (ICC=0.56-0.57). For all tasks, curve analysis revealed poorer reliability at start and end of the landing phase than during the midpart. SIGNIFICANCE: Our data suggests that kinematic evaluations of volleyball-specific jump-landing tasks are reliable to use in screening programs, especially in the sagittal plane. Notably, reliability is poorer at the beginning and end of the landing phase, requiring careful interpretation. In conclusion, the results of this study indicate the potential for integration of sport-specific jump-landing tasks in screening programs, which will be more ecologically valid.

Effects of the stretching program in male volleyball players with posterior shoulder tightness.

BACKGROUND: Stretching programs are often used to improve muscle stiffness and thereby posterior shoulder tightness (PST); however, knowledge about their effects on the viscoelastic properties of muscles and performance is limited. OBJECTIVE: The aim of this study was to investigate the effects of a six-week stretching program on the viscoelastic properties of posterior shoulder muscles, shoulder functional performance and range of motion in volleyball players with PST. STUDY DESIGN: A Randomized Controlled Trial. LEVEL OF EVIDENCE: Level II. METHODS: The study was conducted in 34 male (aged 19-26) professional volleyball players with PST. They were randomly assigned to stretching and control groups. A stretching routine (combining sleeper stretch and cross body stretch exercises) was performed in the stretching group for six weeks. Measurements were taken during the first assessment and six weeks after the initiation of stretching for the following: shoulder external/internal rotation range of motion, spike velocity, single arm seated shot-put test, and infraspinatus- posterior deltoid muscle stiffness (by shear wave elastography). RESULTS: While the stretching group had statistically better results regarding increased shoulder internal rotation (p < 0.01), spike velocity (p = 0.02) and seated single arm shot put distance (p < 0.01), stretching did not have any effect on tissue stiffness. CONCLUSIONS: A 6-week program of sleeper stretch, and cross body stretch exercises improved shoulder internal rotation and functional performance. A clinically meaningful change in muscle mechanical properties cannot be detected after a 6-week stretching program.

Physiological and performance adaptations to beta alanine supplementation and short sprint interval training in volleyball players.

This study aimed to elucidate the impact of combining Beta-Alanine (BA) supplementation with short sprint interval training on cardiorespiratory fitness, anaerobic power, and bio-motor abilities in volleyball players. Twenty young male athletes were randomly divided into 2 equal groups and performed 8 weeks of short sprint interval training while supplementing 4.8 g daily BA or placebo (polydextrose). The players were evaluated for volleyball-specific bio-motor abilities (vertical jump, horizontal jump, spike jump, block jump, 10-m linear sprint, and T-test change of direction speed) and physiological parameters (cardiorespiratory fitness and anaerobic power) pre- and post-intervention. Both groups demonstrated significant (p ≤ 0.05) improvements in all measured variables over time. A time-regimen interaction was observed in jumping ability enhancement from pre- to post-training, wherein BA elicited more significant changes in both vertical and horizontal jumps compared to the placebo. Analyzing residuals in changes and the coefficient of variations (CV) in mean group changes demonstrated that BA supplementation results in uniformly inducing adaptive changes among individuals. Therefore, in light of these results, it is recommended that coaches and trainers take into consideration the utilization of BA as an ergogenic aid to enhance the vertical and horizontal jumps of volleyball players and increase the homogeneity in adaptive responses over the training period.

The effectiveness and types of serves used in elite women's and men's volleyball in the 2021/2022 season.

In elite volleyball, the serve takes an offensive form, aiming to directly score a point or significantly hinder the opponent from launching an attack. Which is why the research aimed to compare the type and effectiveness of the serve in the main round of Tauron and PlusLiga in the 2021/2022 season and update the current knowledge on the types of serves by function and gender. The study analysed observation consisted of 314 women's and men's matches. VolleyStation Pro v 1.29.5; Volleystation z o. o. Poland. Data from the main round matches that took place in the 2021/2022 season in the Polish elite league PlusLiga (182 men's matches) and Tauron Liga (132 women's matches) were used, and the regular season consisted of 2 rounds. The average percentage effectiveness of the serve in women was higher (E = 22%) than in men (E = 15%). In women, only 3 types were observed (JS, JF and W), as much as 86% of all the serves were JF serves. In men, as many as 5 types (JS, JF, FJS, FJF and W), of which over 67% were dynamic JS serves (jumping serve). The serve element has been modified over the years to obtain better effects conducive to winning. Ranging from increasing the speed of the serve, eliminating the serves from the spot in favor of the jump serves, to the use of serves to hide the correct hit of the ball ("Fake"-FFJ, FJS).

Motion extrapolation in sport expertise: Representational momentum and representational gravity in volleyball athletes.

When people indicate the vanishing location of a moving target that suddenly disappears, systematic errors forward (in the direction of motion) and downward (in the direction of gravity) emerge. These spatial displacements were coined, respectively, Representational Momentum and Representational Gravity, and are believed to reflect internalized ecologically relevant physical invariants useful for the anticipation of future states of an event. Previous research has shown that sports athletes exhibit increased Representational Momentum, indicating enhanced motion extrapolation and anticipation, albeit it is still not clear up to what degree this effect is specific for the expertise context or if it generalizes to other dynamic events. Furthermore, the influence of expertise on Representational Gravity, particularly in contexts where anticipation of vertically moving objects is crucial, remains understudied. This study aimed to address these gaps by focusing on Volleyball as a context of expertise due to the prevalence of fast vertically moving balls. Volleyball athletes and non-athletes indicated the perceived offset location of a smoothly moving target, which moved at a constant speed or was subjected to acceleration/deceleration, embedded either in a Volleyball or neutral context. Outcomes revealed that for the Volleyball context, athletes, but not non-athletes, revealed a significant trend to misperceive targets moving along the left diagonal to be further displaced forward beyond what would be expected due to Representational Momentum alone. This finding is discussed in relation to the natural statistics of Volleyball games, where crossed ball trajectories, particularly by the outside hitter, are more prevalent, fast, and offensive, requiring better anticipation to be efficiently dealt with.

Decrease in reaction time for volleyball athletes during saccadic eye movement task: A preliminary study with evoked potentials.

AIM: This preliminary study investigated the differences in event-related potential and reaction time under two groups (athletes vs. non-athletes). MATERIAL AND METHODS: The P300 was analyzed for Fz, Cz, and Pz electrodes in thirty-one healthy volunteers divided into two groups (volleyball athletes and non-athletes). In addition, the participants performed a saccadic eye movement task to measure reaction time. RESULTS: The EEG analysis showed that the athletes, in comparison to the no-athletes, have differences in the P300 in the frontal area (p = 0.021). In relation to reaction time, the results show lower reaction time for athletes (p = 0.001). CONCLUSIONS: The volleyball athletes may present a greater allocation of attention during the execution of the inhibition task, since they have a lower reaction time for responses when compared to non-athletes.

Intra- and inter-operator reliability of measuring compressive stiffness of the patellar tendon in volleyball players using a handheld digital palpation device.

This observational study aimed to evaluate the intra- and inter-operator reliability of a digital palpation device in measuring compressive stiffness of the patellar tendon at different knee angles in talent and elite volleyball players. Second aim was to examine differences in reliability when measuring at different knee angles, between dominant and non-dominant knees, between sexes, and with age. Two operators measured stiffness at the midpoint of the patellar tendon in 45 Dutch volleyball players at 0°, 45° and 90° knee flexion, on both the dominant and non-dominant side. We found excellent intra-operator reliability (ICC>0.979). For inter-operator reliability, significant differences were found in stiffness measured between operators (p<0.007). The coefficient of variance significantly decreased with increasing knee flexion (2.27% at 0°, 1.65% at 45° and 1.20% at 90°, p<0.001). In conclusion, the device appeared to be reliable when measuring compressive stiffness of the patellar tendon in elite volleyball players, especially at 90° knee flexion. Inter-operator reliability appeared to be questionable. More standardized positioning and measurement protocols seem necessary.

Motor alterations along the kinetic chain in amateur volleyball and handball athletes with shoulder pain: An observational comparative study.

Overhead sports overload the shoulder complex due to movement repetition and the great amount of force created during the athletic motion, which may cause adaptations in the shoulder and lead to shoulder pain. However, overhead movements include the kinetic chain, and alterations in some of the structures throughout the kinetic chain may increase stress on the shoulder complex and be associated with shoulder pain. PURPOSE: To compare kinetic chain components in overhead athletes with and without shoulder pain. METHODS: Forty-one volleyball and handball athletes (21 with and 20 without shoulder pain) were included and assessed for hip internal (IR) and external rotation (ER) range of motion (ROM), hip and trunk isometric strength, trunk endurance and neuromuscular control of the lower and upper limbs (Y balance test). RESULTS: Athletes with shoulder pain showed smaller IR ROM in both hips, lower endurance time for trunk extensors and flexors, decreased reach distance in the anterior and posteromedial direction, as well as a smaller composite score in the Y balance test (p < 0.05). CONCLUSION: Volleyball and handball athletes with shoulder pain showed changes in ROM throughout the kinetic chain in addition to lower core endurance, and decreased neuromuscular control of lower limbs.

Pes planus level affects counter movement jump performance: A study on amateur male and female volleyball players.

The aim of this study was to investigate the effect of pes planus level on counter movement jump (CMJ) performance parameters in amateur female and male volleyball players. In this context, amateur volleyball players aged between 18 and 23 years actively playing in the university school volleyball team were included in the study. Pes planus levels of the participants were analyzed using the navicular drop test (NDT). My Jump Lab application was used for CMJ measurement. Within the scope of CMJ, the participants' jump height, force, relative force, power, relative power, average speed, take-off speed, impulse, and flying time were analyzed. According to the linear regression results between NDT and CMJ parameters, force in males (t = 12.93, P = .049) and average speed in females (t = -3.52, P = .017) were significantly associated with NDT. NDT was similar in men and women (P > .05). However, all CMJ parameters were highly different between genders (P < .001). In the correlation analysis between sport age and physical characteristics and CMJ parameters; height (r = .386, P = .046), weight (r = .569, P = .002), leg length (r = .389, P = .045), foot length (r =. 558, P = .005), foot width (r = .478, P = .018), force (r = .407, P = .039), impulse (r = .460, P = .018) parameters, and sport age. The results suggest that the average speed in females and force in males both significantly influenced NDT, highlighting the significance of both factors in predicting NDT scores. Moreover, all CMJ measures showed significant variations between genders, although the NDT scores did not. Furthermore, the correlation analysis demonstrated a strong correlation between a number of physical attributes and CMJ parameters, highlighting the multifaceted nature of athletic performance and indicating the possible impact of these attributes on CMJ results.

Imagining flying increases jumping performance in volleyball players: A pilot study.

OBJECTIVE: The study aimed to examine the effect of mental imagery on sports performance. Specifically, it was tested whether imagining flying (i.e., air travel) increases jumping performance in a group of female volleyball players. METHODS: The study included 46 female young athletes (mean age = 15.23 years; standard deviation = 2.4) divided into two groups: the experimental group viewed a three-dimensional video that simulated a flying experience, while the control group watched neutral footage. The jump performance of both groups was measured before and after viewing the videos, using the Vertec Like® instrument to assess jump height. Participants were assessed for their flow disposition, mental imagery skills, and image vividness. RESULTS: Comparing pre-post jump performance scores, the experimental group showed a significant improvement over the control group, with a medium-large effect size (d = 0.634). There was no significant association between flow disposition, mental imagery skills, image vividness, and pre-post jumping performance differences (respectively: ß = -0.107, p = .484; ß = -0.008, p = .957; ß = 0.024, p = .913). CONCLUSIONS: These findings suggest that the experience of imagining flying, enhanced with an immersive video, has a positive effect on jumping performance in a one-session study with young female volleyball players. This effect does not appear to be associated with pre-existing characteristics or the vividness of the image itself.

Sex-specific relationship patterns between body morphology and maturity status with change of direction and agility in elite adolescent volleyball players.

This study explored sex-specific patterns in the relationship between maturity, body morphology, and change of direction (COD) and agility (AG) in adolescent volleyball players. The sample comprised 22 males and 24 females aged 15-17 with at least 4 years of sports experience. Measurements included body height, weight, muscle and fat mass, leg length, and center of mass. The study determined the Age of Peak Height Velocity (APHV) and evaluated sensorimotor ability through pre-planned COD and not-planned AG five-time shuttle runs, measuring the time difference as the index of reactivity. Positive correlations were found between COD and AG with fat mass index (FMI) in boys, while negative relative lower limb length (rLL) correlated with COD. In females, age of peak height velocity (APHV) showed a significant negative relationship with sensorimotor ability. Linear and polynomial regressions confirmed predictive and curvilinear relationships, respectively. Cluster analysis identified different associations in boys and girls, emphasizing sex-specific patterns. Body fat percentage had a negative impact on COD-AG in boys, while the optimal lower limb length proportion positively influenced COD due to enhanced maneuverability. Maturation affected sensorimotor abilities in girls. The findings suggest a need for a tailored approach to COD-AG development based on sex-specific considerations in adolescent volleyball players.

A New Training Load Quantification Method at Supramaximal Intensity and Its Application in Injuries Among Members of an International Volleyball Team.

ABSTRACT: Bouzigues, T, Maurelli, O, Imbach, F, Prioux, J, and Candau, R. A new training load quantification method at supramaximal intensity and its application in injuries among members of an international volleyball team. J Strength Cond Res 38(8): 1453-1463, 2024-The quantification of training loads (TLs) is essential for optimizing jump performance and reducing the occurrence of injuries. This study aimed to (a) propose a new method for quantifying TLs in explosive exercises, (b) determine the nature of the relationship between TLs dynamics and injury occurrence, and (c) assess a TL critical for training schedule purposes, above which the risk of injury occurrence becomes unacceptable. This study was conducted with 11 male volleyball players on a national team during a 5-month international competitive period. The proposed new method for quantifying TLs is based on a weighting factor applied to relative jumping intensities, determined by the number of sustainable jumps and their intensities measured by G-Vert accelerometer. The relationship between TLs dynamics and injury occurrence was assessed using a variable dose-response model. A high coefficient of determination was found between the maximum number of jumps possible and their intensities ( r2 = 0.94 ± 0.14, p < 0.001), indicating a strong physiological relationship between jumping intensities and the constraints imposed. The occurrence of injury was dependent on TLs dynamics for 2 players ( r2 = 0.26 ± 0.01; p < 0.001). The TL critical corresponded to 11 jumps over 80% of maximum jump height during games and approximately 130 jumps at <80% of maximal jump height. The present study proposes a new approach for quantifying supramaximal exercises and provides tools for training schedules and the prevention of volleyball injuries.