Dynamic Characteristics of Approach Spike Jump Tasks in Male Volleyball Players

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.

Biomechanical Analysis of Staples for Epiphysiodesis

Limb asymmetry can, and often does, cause various health problems. Blount bone staples (clips) are used to correct such uneven growth. This article analyzes the performance of a biomechanical staple during bone (tibia) growth arrest. The staples considered in this study were made of 1.4441 stainless steel, the model of tibia consisted of two materials representing corticalis and spongiosis. Hooke’s law was used for modeling materials’ behaviors for finite element analysis (FEA). The maxima of stress and total staple displacement were evaluated using the finite element method and verification of the results, along with the determination of the maximum loading (growing) force that the staples are capable of withstanding, was performed experimentally. The presented method can be used to determine the safety and usability of staples for bone growth arrest. According to our results, the design of Blount staples considered in this paper is safe and suitable for orthopedic treatment.

Unilateral versus Bilateral Landing after Spike Jumps in Male and Female Volleyball: A Systematic Review

Background: The spike is a key action in volleyball, and the landing technique and its asymmetries are commonly associated with an increased risk of injury. Objectives: The aim of this systematic review was to assess how male and female volleyball players land (i.e., unilaterally, or bilaterally) after spike jumps in matches and analytical settings (field or laboratory). Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines were followed, with eligibility criteria defined according to participants, interventions, comparators, study design (PICOS): (p) healthy indoor volleyball players of any sex, age group, or competitive level; (i) exposure to landing after spike actions during official matches AND/OR simulated 6 vs. 6 games AND/OR analytical training conditions AND/OR laboratorial experiments; (c) not mandatory; (o) data on landing mechanics after spike actions, including reporting of whether the landing was unilateral or bilateral; (s) no restrictions imposed on study design. Searches were performed in seven electronic databases (Cochrane Library, EBSCO, PubMed, Scielo, Scopus, SPORTDiscus, and Web of Science) on 23 April 2021. Results: Automated searches provided 420 results. Removal of 119 duplicates resulted in 301 records being screened for titles and abstracts. A total of 25 studies were eligible for full-text analysis. Of these, eight studies were deemed eligible for inclusion in the review. Studies showed that (i) attackers landed asymmetrically 68% of the times (61% left leg, 7% right leg); (ii) bilateral asymmetries were observed for the hip, knee, and ankle joints; (iii) bilateral asymmetries were observed even when players were instructed to land evenly on two feet; (iv) landing contact of the leg opposite to the hitting arm preceded the contact of the homolateral leg. One match analysis study showed that men landed more often on the left (31.5%) or right foot (8.5%) than women (23.7% and 1.6%). Conclusions: Studies analyzing spike landing showed a prevalence of unilateral landings (mostly the left leg first, for right-handed players) in men and women but more prevalently in men. Registration INPLASY202140104, DOI: 10.37766/inplasy2021.4.0104.