Iskanje po repozitoriju

Opis: An essential aspect of jumping performance is the ability to control impact forces. One of the key measures of this ability is the damping ratio, a dimensionless parameter that quantifies the rate at which oscillations decay following a disturbance. This study aims to assess the intra-session and inter-session reliability of damping ratios at different lower-limb anatomical landmarks and evaluate their sensitivity in detecting differences between various repetitive jumping forms, with an emphasis on establishing a specific methodological approach. Twenty-three physically active male and female students performed maximal countermovement jumps (CMJs) and bilateral (BL) and unilateral (UL) hopping (HOP). Ten wireless inertial measurement units recorded inertial data of five bilateral lower-limb anatomical landmarks. Results showed that the damping ratios during CMJ and HOPUL demonstrated good reliability, whereas in HOPBL were moderately reliable. The damping ratios of nearly all the anatomical landmarks differed between the jumping forms. CMJ had the highest values, HOPBL the lowest, and HOPUL values in between, likely due to variations in joint stiffness and amplitude displacement, as well as stretch‒shortening cycle reliance. Methodologically, using 20 repetitions in an intra-session trial and averaging left and right sides for inter-session reliability and inter-jump sensitivity, damping ratios are acceptably reliable and sufficiently sensitive for biomechanical analysis of different repetitive jumping forms. This metric could potentially be a valuable tool in developing theoretical nonlinear multibody mass‒spring‒damper models and could enhance biomechanical analysis with practical applications in sports training and rehabilitation.
Ključne besede: stretch–shortening cycle, stiffness, impact absorption, oscillation, intraclass, correlation coefficient
Objavljeno v RUP: 13.04.2026; Ogledov: 498; Prenosov: 11
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Opis: Our objective was to investigate the effects of three hip flexion angles (0°, 45°, and 90°) and leg dominance on peak joint torque, angle at peak torque, and peak electromyographic activity (EMGA) of the adductor longus during bilateral eccentric hip adduction. Sixteen recreationally active participants completed bilateral eccentric contractions at each hip flexion angle using a custom-built dynamometer. The primary outcome measures were peak adduction torque, angle at peak torque, and EMGA of the adductor longus. A 3×2 repeated measures ANOVA was used to assess the effects of hip angle and leg dominance. Hip flexion angle had a significant main effect on peak torque (F(2, 30) = 15.75, p<0.01), with peak torque significantly lower at 90° compared to 0° and 45°. No significant effects were observed for leg dominance or interaction. No significant main effects of hip flexion angle, leg dominance, or their interaction were observed on peak EMGA or peak torque angle. Eccentric hip adduction strength is reduced at 90° of flexion, likely due to mechanical disadvantage, while neural activation remains unchanged. These findings support the use of less flexed positions in eccentric training protocols for adductor strength development or injury prevention.
Ključne besede: adductor longus, eccentric training, injury prevention, strength
Objavljeno v RUP: 19.11.2025; Ogledov: 1018; Prenosov: 19
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