Fordfunder3848

Z Iurium Wiki

Verze z 9. 9. 2024, 13:20, kterou vytvořil Fordfunder3848 (diskuse | příspěvky) (Založena nová stránka s textem „In musculoskeletal modelling, adjusting model parameters is challenging. This paper proposes a multivariate statistical methodology to adjust muscle force-…“)
(rozdíl) ← Starší verze | zobrazit aktuální verzi (rozdíl) | Novější verze → (rozdíl)

In musculoskeletal modelling, adjusting model parameters is challenging. This paper proposes a multivariate statistical methodology to adjust muscle force-generating parameters optimally. Dynamic residuals are minimized as muscle force-generating parameters are varied (maximal isometric force, optimal fiber length, tendon slack length and pennation angle).First, a sensitivity and a Pareto analyses are carried out in order to sort out and screen the set of parameters having the greatest influence regarding the dynamic residuals. These parameters are then used to create a response surface following a Design of Experiments (DoE) approach. Finally, this surface is used to determine the optimum levels of the design variables (muscle force-generating parameters). The proposed methodology is illustrated by the adjustment of a three-dimensional musculoskeletal model of a sheep forelimb. After adjustment, the reserve actuator values of the elbow and wrist joints were reduced, on average, by 18%, and 16%, respectively. These results demonstrate that the use of multivariate statistical strategies is an effective way to adjust model parameters optimally while reducing dynamic inconsistencies. This study constitutes a step towards a more robust methodology in musculoskeletal modelling, focusing on muscular parameter tuning. Control of the centre of mass (CoM) whilst minimising the use of unnecessary movements is imperative for successful performance of dynamic sports tasks, and may indicate the condition of whole-body dynamic stability. The aims of this study were to express movement strategies that represent whole-body dynamic stability, and to explore their association with potentially injurious joint mechanics and side cutting performance. Twenty recreational soccer players completed 45° unanticipated side cutting. Five distinct whole-body dynamic stability movement strategies were identified, based on factors that influence the medial ground reaction force (GRF) vector during ground contact in the side cutting manoeuvre. Using Statistical Parametric Mapping, the movement strategies were linearly regressed against selected performance outcomes and peak knee abduction moment (peak KAM). Significant relationships were found between each movement strategy and at least one selected performance outcome or peak KAM. Our results suggest excessive medial GRFs were generated through sagittal plane movement strategies, and despite being beneficial for performance aspects, poor sagittal plane efficiency may destabilise control of the CoM. Frontal plane hip acceleration is the key non-sagittal plane movement strategy used in a corrective capacity to moderate excessive medial forces. However, whilst this movement strategy offered a way to retrieve control of the CoM, mitigating reduced whole-body dynamic stability, it also coincided with increased peak KAM. Overall, whole-body dynamic stability movement strategies helped explain the delicate interplay between the mechanics of changing direction and undesirable joint moments, providing insights that might support development of future intervention strategies. To assess the test - retest reliability and sensitivity of an instrument developed to measure the passive mechanical properties of the midfoot joint complex (MFJC), nine female and three male healthy young adults were evaluated in two different days by two experienced examiners. After proper participant positioning on the instrument, the left forefoot was passively moved from eversion (20°) to inversion (45°) at 2°/s, while the rearfoot and shank were kept immobile. From the instrument's sensing units (torque meter and potentiometer at 100 Hz), passive torque and angle data were registered. Passive stiffness was calculated as the instantaneous slope of the torque vs. angle curve. Therefore, the variables analyzed were resting angle, passive torques and stiffnesses during inversion and eversion through the intraclass correlation coefficient (ICC3,3), standard error of measurement (SEM) and minimal detectable change (MDC95). For the resting angle, ICC3,3 ranged from 0.85 to 0.91, SEM ranged from 1.54° to 1.95° and MDC95 ranged from 4.26° to 5.41°. For the torques, ICC3,3 ranged from 0.85 to 0.97, SEM ranged from 0.09Nm to 0.42Nm and MDC95 ranged from 0.26Nm to 1.16Nm. Finally, for the stiffnesses, ICC3,3 ranged from 0.79 to 0.98, SEM ranged from 0.01Nm/° to 0.04Nm/° and MDC95 ranged from 0.01Nm/° to 0.10 Nm/°. It can be concluded that most of the measurements presented good to excellent reliability with low measurement error. Hence, clinicians and researchers may benefit from the reliable and stable measures provided by the Foot Torsimeter when assessing patients and planning interventions. Despite many in vitro mechanical experiments of tendon being conducted at room temperature, few assessments have been made to determine how the structural response of tendon to mechanical overload may vary with ambient temperature. We explored whether damage to the collagen nanostructure of tendon resulting from tensile rupture varies with temperature. Use of bovine tail tendons in combination with NaBH4 crosslink stabilization treatment allowed us to probe the mechanisms underlying the observed changes. Untreated tendons and NaBH4-stabilized tendons were pulled to rupture at temperatures of 24, 37, and 55 °C. Of nine mechanical parameters measured from the resulting stress-strain curves, only yield stress differed between the tendons tested at 37 and 24 °C. When tested at 55 °C, untreated tendons showed large reductions in ultimate strength and toughness, while NaBH4-stabilized tendons showed smaller reductions. check details Differential scanning calorimetry was used to assess damage to the collagen fibril nanostructure of tendons resulting from rupture, with samples from the ruptured tendons compared to samples from the same tendons removed prior to loading. While there was indication that overload-induced molecular packing disruption to collagen fibrils may be heightened at 37 °C, statistical increases in damage compared to that occurring at 24 °C were only seen when testing was conducted at 55 °C. The results show that the temperature sensitivity of tendon to ramp loading depends on crosslinking within the tissue. In poorly crosslinked tissues, collagen may be more susceptible to mechanical damage when tested at physiologic temperature compared to room temperature. For tendons with a high density of thermally stable crosslinks, such as the human Achilles or patellar tendons, testing at room temperature should produce comparable results to testing at physiologic temperature.

Autoři článku: Fordfunder3848 (Goldberg Vestergaard)