Physical abilities modelling has a profound connection with long-term athlete development and talent identification. There is not enough data to support evidence about age-related changes in volleyball players’ isometric strength. This study aimed to define the age-related model of volleyball players multidimensional muscles’ contractile characteristics. The participants were divided according to gender (male n = 112, female n = 371) and according to age into four groups: under 15 (U15), under 17 (U17), under 19 (U19), and under 21 (U21) years old. Participants performed three isometric strength tests: handgrip, lumbar extensors, and ankle extensors. Maximal force and rate of force development results from all three tests were transformed into a single Score value as a representation of contractile potentials using principal component analysis. The main findings were that Score values of both genders showed significant differences between age groups (male: F = 53.17, p < 0.001; Female: F = 41.61, p < 0.001). Trends of those yearly changes were slightly more balanced for female subjects (3.9%) compared to male subjects (6.3%). These findings could help in strength training adjustments when working with volleyball players of a certain age, and enable coaches to detect ones that stand out positively, considering them as strong in regard to their age.

This study examines the differences in the anthropometric characteristics and motor abilities of young elite female volleyball players depending on their playing position. This study was conducted with 114 U17 female players of the Serbian national team (age: 15.4 ± 0.4 years; body mass: 65.8 ± 7.8 kg; height: 176.8 ± 7.7 cm). All participants had at least four years of volleyball experience. A one-way ANOVA revealed significant differences (p ≤ 0.05) in body mass (BM), body height (BH), body mass index (BMI), one-arm standing reach (1ARS), two-arm standing reach (2ARS), arm span, a medicine ball throw (MT), standing long jump (SLJ), squat jump (SJ), countermovement jump without an arm swing (CMJ), 5 m sprint (S5), 15 m sprint with a flying start (S15), 20 m sprint (S20), and t-test (TT). The results show that a player’s position significantly impacts their anthropometric characteristics and motor abilities, with liberos requiring agility and flexibility, while middle blockers and opposite hitters focus on strength and explosiveness. Outside hitters and setters achieved high results in jump tests, while outside hitters, although agile, had slightly lower results in the long jump. The results confirm that BH and BM, 1ARS, 2ARS, arm span, explosive power, agility, speed, and flexibility significantly impact performance, indicating that a player’s position affects their anthropometric characteristics and motor abilities.

Introduction When a person is in a standing position, the plantar flexor muscles are involved in most static and dynamic body movements. Objectives The aim of this study was to investigate the trial to trial and factorial reliability of measuring the contractile characteristics of PF muscles using a simple novel field test. Methods The sample consisted of 452 healthy subjects, 120 male and 332 female. The research was conducted by means of the trial to trial testing method, using isometric dynamometry performed in field conditions. ANOVA was used to estimate the differences among the trials, Cronbach’s alpha and interclass correlation to estimate the correlations among the trials, and principal component analysis to evaluate the contribution of each trial to overall variability. Results The main findings of this study are that trials differed significantly (p0.9), proving that measuring was reliable, and the factorial analysis separated the second and third trials, the second trial accounting for most of the total variability. Conclusions The simple novel field test for the measurement of plantar flexor contractile characteristics recommended by this study proved to be as highly reliable as laboratory testing, but was easy to perform in conditions outside of scientific or diagnostic institutions, which greatly facilitates the work of scientists, coaches and professionals. Level of Evidence II; Diagnostic Studies – Investigating a diagnostics test.

The two-point force-velocity model allows the assessment of the muscle mechanical capacities in fast, almost fatigue-free conditions. The aim of this study was to investigate the concurrent validity of the two-point parameters with directly measured force and power and to examine the generalization of the two-point parameters across the different functional movement tests of leg muscles. Twelve physically active participants were tested performing three functional lower limb maximal tests under two different magnitudes of loads: countermovement jumps, maximal cycling sprint, and maximal force under isokinetic conditions of the knee extensors. The results showed that all values from the two-point model were higher than the values from the standard tests (p < 0.05). We also found strong correlations between the same variables from different tests (r ≥ 0.84; p < 0.01), except for force in maximal cycling sprint, where it was low and negligible (r = −0.24). The results regarding our second aim showed that the correlation coefficients between the same two-point parameters of different lower limb tests ranged from moderate to strong (r −0.47 to 0.72). In particular, the relationships were stronger between power variables than between force variables and somewhat stronger between standard tests and two-point parameters. We can conclude that mechanical capacities of the leg muscles can be partially generalized between different functional tests.

This study explored the changes in the rate of torque development scaling factor (RTD-SF) and maximum voluntary isometric contraction (MVC) variables following six weeks of unilateral isometric electromyostimulation (EMS) and voluntary (VOL) exercises. Twenty-six physically active participants were randomly assigned to EMS (n = 13) or a VOL group. MVC and RTD-SF of the quadriceps femoris of both legs were assessed before and after training. EMS and VOL exercises had identical frequency (three sessions/week), intensity (60% MVC), volume (40 contractions), and work-to-rest ratio (18 min: 6.25 s of work/20 s of rest). There were no between-group differences for the trained leg with overall increases in maximal torque (Tmax) of ~29% (d = 2.11–2.12), ~13% for RTDmax (d = 0.92–1.10); ~23% for Intercept (d = 0.72–0.78), and reduction in RTD-SF by ~15% (d = 1.01–1.10). In the non-trained leg, significant moderate change was only observed after EMS for RTD-SF which decreased by 12.5% (d = 0.76). Both EMS and VOL training applied at equivalent workloads positively impact on Tmax, RTDmax, and Intercept, but they negatively affect the quickness with which muscle contracts across a wide range of submaximal forces. Using a moderate training intensity in regularly physically active participants could explain the absence of cross-education in the VOL group.