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Ključne besede: jump, force, power
Objavljeno v RUP: 14.05.2026; Ogledov: 197; Prenosov: 8
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Opis: This study aimed to evaluate the Force-Velocity (Fv) profile of elite female volleyball players during the Squat Jump and Countermovement Jump to define the Fv profile of female athletes based on strength, power, and individual mechanical characteristics. The goal was to enhance training efficiency and improve performance in ballistic movements. For this study, we recruited 12 elite female volleyball players from the Montenegro U19 national team. The Fv profile was assessed in two types of muscle contractions: the Squat Jump (concentric contraction) and the Countermovement Jump (eccentric-concentric contraction) to determine Fv imbalance. First, the height of the jump was measured in the Squat Jump, followed by the Countermovement Jump. After that, the Fv profile was analyzed under both contraction types to assess potential imbalances. The results showed an Fv imbalance of 24.93% during the concentric muscle contraction and 29.71% during the eccentric-concentric muscle contraction. Based on these findings, it is suggested that training should prioritize enhancing strength capabilities while simultaneously addressing Fv imbalances. Reducing theoretical Fv imbalance could serve as a supplementary component of training to improve overall physical. performance.
Ključne besede: jump, force, velocity, volleyball
Objavljeno v RUP: 30.06.2025; Ogledov: 1139; Prenosov: 5
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Ključne besede: water splitting, photo electrochemistry, molecular dynamics, classical force fields, ab initio simulations
Objavljeno v RUP: 16.07.2021; Ogledov: 3633; Prenosov: 44
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Opis: Background: Within the current study we aimed at exploring gender-related differences and the relationship between sprint start block kinematics and kinetics and sprint acceleration force-velocity (F-v) relationship parameters (maximal force [F0], maximal velocity [v0], maximal power [Pmax] and slope) in top national-level sprinters. (2) Methods: Twenty-eight sprinters (6 females) performed 10 maximal 30-m sprints. Start block and acceleration kinematics and kinetics were collected with an instrumented sprint start block and a laser distance sensor (KiSprint system). Displacement-time data were used to determine the F-v relationship through Samozino's method. (3) Results: Start block rear foot maximal force (effect size [ES] = 1.08), rate of force development (ES = 0.90-1.33), F0 (ES = 1.38), v0 (ES = 1.83) and Pmax (ES = 1.95) were higher in males than in females (p -< 0.05). There were no differences in the slope, and ratio of horizontal-to-resultant force. F0, v0, and Pmax generally presented higher correlations with the start block kinetics (median r [range] = 0.49 [0.28, 0.78]) than with the kinematics (median r [range] = -0.27 [-0.52, 0.28]). (4) Conclusions: We confirmed that sprint block phase and sprint acceleration mechanics should be mutually assessed when analyzing sprinting performance. KiSprint system could provide more accurate information regarding mechanical pattern and technique during sprint initiation and acceleration, and potentially help create a more personalized and effective training program.
Ključne besede: force-velocity relationship, force platform, kinematics, kinetics, track-and-field
Objavljeno v RUP: 10.09.2020; Ogledov: 2957; Prenosov: 88
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Opis: We analysed the effects of task symmetry during bilateral accurate force production tasks performed by the two feet. In particular, we tested a hypothesis that bilateral deficit would lead to higher indices of synergies defined as co-varied adjustments in the two forces across trials that reduced total force variability. The subjects produced steady-state force followed by a quick force pulse into the target. The two feet could be acting both into plantar flexion and into dorsiflexion (symmetrical tasks), or in opposite directions (asymmetrical task). We used the framework of the uncontrolled manifold hypothesis to quantify two variance components, one of which did not change total force (VUCM), while the other did (VORT). Synergy indices during the asymmetrical task were higher than in either symmetrical task. The difference was due to higher VUCM (compared to the symmetrical plantar flexion task) or lower VORT (compared to the symmetrical dorsiflexion task). The synergy index showed a drop (anticipatory synergy adjustment, ASA) starting 100150 ms prior to the force pulse initiation. The ASA tended to be shorter and of a smaller magnitude for the asymmetrical task. This is the first demonstration of bilateral synergies during accurate force production by the legs. We conclude that bilateral deficit has no or weak effects on two-leg synergies. The results fit the earlier introduced scheme with two groups of neural variables defining average performance of a redundant system and patterns of co-variation among its elemental variables, respectively
Ključne besede: kinesiology, force, synergy, legs, bilateral deficit, symmetry
Objavljeno v RUP: 15.10.2013; Ogledov: 40186; Prenosov: 249
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