Development of a subject-specific computational musculoskeletal trunk model (accounting for age, sex, body weight and body height), estimation of muscle forces and internal loads as well as ...subsequent validation by comparison with measured intradiscal pressure in various lifting tasks are novel, important and challenging. The objective of the present study is twofold. First, it aims to update and personalize the passive and active structures in an existing musculoskeletal kinematics-driven finite element model. The scaling scheme used an existing imaging database and biomechanical principles to adjust muscle geometries/cross-sectional-areas and passive joint geometry/properties in accordance with subjects’ sex, age, body weight and body height. Second, using predictions of a detailed passive finite element model of the ligamentous lumbar spine, a novel nonlinear regression equation was proposed that relates the intradiscal pressure (IDP) at the L4–L5 disc to its compression force and intersegmental flexion rotation. Predicted IDPs and muscle activities of the personalized models under various tasks are found in good-to-excellent agreement with reported measurements. Results indicate the importance of personal parameters when computing muscle forces and spinal loads especially at larger trunk flexion angles as minor changes in individual parameters yielded up to 30 % differences in spinal forces. For more accurate subject-specific estimation of spinal loads and muscle activities, such a comprehensive trunk model should be used that accounts for subject’s personalized features on active musculature and passive spinal structure.
The elephant proboscis (trunk), which functions as a muscular hydrostat with a virtually infinite number of degrees of freedom, is a spectacular organ for delicate to heavy object manipulation as ...well as social and sensory functions. Using high-resolution motion capture and functional morphology analyses, we show here that elephants evolved strategies that reduce the biomechanical complexity of their trunk. Indeed, our behavioral experiments with objects of various shapes, sizes, and weights indicate that (1) complex behaviors emerge from the combination of a finite set of basic movements; (2) curvature, torsion, and strain provide an appropriate kinematic representation, allowing us to extract motion primitives from the trunk trajectories; (3) transport of objects involves the proximal propagation of an inward curvature front initiated at the tip; (4) the trunk can also form pseudo-joints for point-to-point motion; and (5) the trunk tip velocity obeys a power law with its path curvature, similar to human hand drawing movements. We also reveal with unprecedented precision the functional anatomy of the African and Asian elephant trunks using medical imaging and macro-scale serial sectioning, thus drawing strong connections between motion primitives and muscular synergies. Our study is the first combined quantitative analysis of the mechanical performance, kinematic strategies, and functional morphology of the largest animal muscular hydrostat on Earth. It provides data for developing innovative “soft-robotic” manipulators devoid of articulations, replicating the high compliance, flexibility, and strength of the elephant trunk.
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•Elephants evolved strategies reducing the biomechanical complexity of their trunk•Object transport is achieved by propagating inward curvature from the trunk tip•The trunk can form rigid segments connected by pseudo-joints for point-to-point motion•The trunk tip tangential velocity obeys a power law with its path curvature
Dagenais et al. uncover the biomechanics of the elephant trunk, showing that complex behaviors emerge from a finite set of basic movements. Curvature, torsion, and strain provide an efficient kinematic representation to decompose trunk trajectories into motion primitives. The trunk forms pseudo-joints and its tip follows a speed-curvature power law.
To verify whether trunk control test (TCT) upon admission to intensive inpatient post-stroke rehabilitation, combined with other confounding variables, is independently associated with discharge mBI.
...Multicentric retrospective observational cohort study.
Two Italian inpatient rehabilitation units.
A total of 220 post-stroke adult patients, within 30 days from the acute event, were consecutively enrolled.
Not applicable.
The outcome measure considered was the modified Barthel Index (mBI), one of the most widely recommended tools for assessing stroke rehabilitation functional outcomes.
All variables collected at admission and significantly associated with mBI at discharge in the univariate analysis (TCT, mBI at admission, pre-stroke modified Rankin Scale mRS, sex, age, communication ability, time from the event, Cumulative Illness Rating Scale, bladder catheter, and pressure ulcers) entered the multivariate analysis. TCT, mBI at admission, premorbid disability (mRS), communication ability and pressure ulcers (P<.001) independently predicted discharge mBI (adjusted R
=68.5%). Concerning the role of TCT, the model with all covariates and without TCT presented an R
of 65.1%. On the other side, the model with the TCT only presented an R
of 53.1%. Finally, with the inclusion of both TCT and all covariates, the model showed an R
increase up to 68.5%.
TCT, with other features suggesting functional/clinical complexity, collected upon admission to post-acute intensive inpatient stroke rehabilitation, independently predicted discharge mBI.
BACKGROUNDSacroiliac joint (SIJ) motion has been documented using invasive and noninvasive kinematic techniques. No study has explored SIJ angular positions in functional postures using noninvasive ...techniques. The purpose of this study was to quantify SIJ positioning among different seated postures in a healthy population. METHODSTwelve female and 11 male healthy young participants participated. Left and right anterior and posterior superior iliac spines were manually digitized during standing, neutral sitting and four different seated postures. Rigid bodies recorded the kinematics of the lumbar spine. Angles calculated included transverse sacroiliac angle, innominate sagittal angle, sacral tilt, lumbar flexion-extension, lumbar lateral bend and lumbar axial twist. FINDINGSThe observed range of angular positions was approximately 3 to 4 degrees across the SIJ-related angles. The main effect of seated posture was observed for all angles measured. The main effect of sex was observed for all angles except lumbar lateral bending. Females consistently experienced more posterior sacral tilt than males. Interaction effects between sex and posture were only observed at the right-transverse sacroiliac angle and sacral tilt. Previous sitting posture affected the subsequent neutral sitting posture for the right-transverse sacroiliac angle and lumbar spine angle. INTERPRETATIONSIJ angular position differences among the seated postures were similar in magnitude to motions previously reported in participants undergoing prone passive hip abduction and external rotation. Sex differences, including greater sacral posterior tilt observed in females, likely reflect underlying morphological and physiological differences. Future studies should explore SIJ positioning during functional tasks in pathological populations to help elucidate the underlying causes of SIJ pain and inform treatment strategies.
Rural regions in industrialised countries are facing problems in public transport (PT) provision against the backdrop of demographic change, urbanisation and austerity policies. However, innovative ...mobility concepts evolve under technological developments. Demand responsive transport (DRT) has been identified in research to meet the challenges and efficiently improve mobility through the concept of ride-pooling. Still, most of these DRT services are being investigated in urban settings with high mobility demand and population density. Research on low-demand regions, such as the Oberharz in Germany, is rarely considered. Moreover, the applied DRT services come with several restrictions regarding stop locations, customer target groups or spatial restrictions. Therefore, this paper fills this gap through spatial and temporal analysis of a real-life, fully flexible and true door-to-door DRT experiment. Over a 6-months period around 38,000 trips took place in the Oberharz. The analysis of these trips shows that an unrestricted DRT service between three main centres (Goslar, Clausthal-Zellerfeld and Osterode) results in main travel axes between these cities while the more remote areas forfeit mobility to these centres of public service provision. Consequently, a feeder-trunk system should be favoured for future DRT services in low-demand areas to sustainably improve mobility in remote regions. The complementary extension of the existing PT through such a DRT service should then meet mobility needs of rural areas to redeem car dependency and improve mobility for all population groups.
•Under a fully flexible, door-to-door DRT service in a rural area travel axes form between larger cities in the area.•A feeder-trunk concept or a demand responsive connector may increase viability of DRT services even in rural areas.•Temporal and spatial booking constraints are suitable to improve overall DRT system performance.•Rural population accepts innovative DRT service and prefers using the smartphone app for bookings.
Abstract Background Context Heterogeneity exists within the low back pain population. Some patients recover after every pain episode, whereas others suffer daily from LBP complaints. Until now, ...studies rarely make a distinction between recurrent low back pain (RLBP) and chronic low back pain (CLBP), although both are characterized by a different clinical picture. Clinical experiences also indicate that heterogeneity exists within the CLBP population. Muscle degeneration, like atrophy, fat infiltration, alterations in muscle fiber type and altered muscle activity, compromises proper biomechanics and motion of the spinal units in low back pain (LBP) patients. The amount of alterations in muscle structure and muscle function of the paraspinal muscles, might be related to the recurrence or chronicity of LBP. Purpose The aim of this experimental study is to evaluate differences in muscle structure (cross-sectional area and lean muscle fat index) and muscle activity of the multifidus (MF) and erector spinae (ES) during trunk extension, in patients with RLBP, non-continuous CLBP and continuous CLBP. Study Design and Setting This cross-sectional study took place in the University hospital of Ghent, Belgium. Muscle structure characteristics and muscle activity were assessed by magnetic resonance imaging (MRI). Patient Sample Fifty five adults with non-specific low back pain (24 RLBP in remission, 15 non-continuous CLBP, 16 continuous CLBP) participated in this study. Outcome Measures Total cross-sectional area, muscle cross-sectional area, fat cross-sectional area, lean muscle fat index, T2-rest and T2-shift were assessed. Methods A T1-weighted Dixon MRI scan was used to evaluate spinal muscle cross-sectional area and fat infiltration in the lumbar MF and ES. Muscle functional MRI was used to evaluate the muscle activity of the lumbar MF and ES during a lumbar extension exercise. Before and after the exercise, a pain assessment was performed. This study was supported by grants from the Special Research Fund of Ghent University (DEF12/AOP/022) without potential conflict of interest-associated biases in the text of the paper. Results Fat cross-sectional area and lean muscle fat index was significantly higher in MF and ES in continuous CLBP compared to non-continuous CLBP and RLBP (p<0.05). No differences between groups were found for total cross-sectional area and muscle cross-sectional area in MF or ES (p>0.05). Also no significant differences between groups for T2-rest were established. T2-shift, however, was significantly lower in MF and ES in RLBP compared to respectively non-continuous CLBP and continuous CLBP (p<0.05). Conclusion These results indicate a higher amount of fat infiltration in the lumbar muscles, in the absence of clear atrophy, in continuous CLBP compared to RLBP. A lower metabolic activity of the lumbar muscles was seen in RLBP replicating a relative lower intensity in contractions performed by the lumbar muscles in RLBP compared to non-continuous and continuous CLBP. In conclusion, RLBP differ from continuous CLBP for both muscle structure and muscle function, whereas non-continuous CLBP seem comparable with RLBP for lumbar muscle structure and with continuous CLBP for lumbar muscle function. These results underline the differences in muscle structure and muscle function between different LBP populations.
•Ability to maintain a seated position is influenced by level of activity.•High level of activity produces stable static cervical and thoracic trunk position.•Moderate or low level of activity ...exhibited postural impairment over time.•Physical activity should be encouraged in older adults to maintain a proper posture.
to assess the impact of physical activity (PA) levels on sitting posture in the older adults.
One hundred and twenty individuals were divided into three groups according their PA levels: vigorous group (VG); moderate group (MG); low group (LG). The ability to maintain static trunk posture in sitting position as assessed based on the cervical angle (CA) and thoracic angle (TA) was measured.
There were no significant differences between measurements in CA for the VG. However, LG and MG participants exhibited a significant decrease in CA from minute 1 to 10 and from minute 2 to 10, respectively. In the thoracic region, only the MG exhibited significant differences in TA from minute 2 to 10 compared to minute 1 (p < 0.05). No significant differences were found in TA between measurements for either VG or LG.
PA has a high impact on the ability to maintain static trunk posture in the older adults.
Purpose This study aimed to clarify the characteristics of movement when lifting loads at defined stance widths, and the associated mechanical stress in the lumbar region. Subjects and Methods Eight ...healthy, male university students lifted a 10 kg load placed on the floor using three stance widths. High-speed cameras and surface electromyography were used to measure body movements and muscle activities. Results Anterior tilt angle of the trunk and activity of the lumbar paraspinal muscles were significantly decreased when using a wide stance. There were no significant differences in the activities of the lower extremity muscles. Conclusion These results suggest that use of a wide stance while lifting loads decreases the anterior tilt angle of the trunk and the activity of the lumbar paraspinal muscles, which would decrease mechanical stress on the lumbar region.
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