Articles de revues : « Mechanical movements Biomechanics »

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Hood, Simon, Thomas McBain, Matt Portas et Iain Spears. « Measurement in Sports Biomechanics ». Measurement and Control 45, n^o 6 (juillet 2012) : 182–86. http://dx.doi.org/10.1177/002029401204500604.

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One of the major roles of a sports biomechanist or coach is to assess the movement patterns within sports performances. Movements can be analysed to enhance an individual's technique in terms of efficiency or to provide technical advantage. This paper aims to highlight the different measurement techniques available for the biomechanist to assess the movement characteristics of the technical and mechanical aspects of athletic performance.

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Verbruggen, Stefaan W., Bernhard Kainz, Susan C. Shelmerdine, Joseph V. Hajnal, Mary A. Rutherford, Owen J. Arthurs, Andrew T. M. Phillips et Niamh C. Nowlan. « Stresses and strains on the human fetal skeleton during development ». Journal of The Royal Society Interface 15, n^o 138 (janvier 2018) : 20170593. http://dx.doi.org/10.1098/rsif.2017.0593.

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Mechanical forces generated by fetal kicks and movements result in stimulation of the fetal skeleton in the form of stress and strain. This stimulation is known to be critical for prenatal musculoskeletal development; indeed, abnormal or absent movements have been implicated in multiple congenital disorders. However, the mechanical stress and strain experienced by the developing human skeleton in utero have never before been characterized. Here, we quantify the biomechanics of fetal movements during the second half of gestation by modelling fetal movements captured using novel cine-magnetic resonance imaging technology. By tracking these movements, quantifying fetal kick and muscle forces, and applying them to three-dimensional geometries of the fetal skeleton, we test the hypothesis that stress and strain change over ontogeny. We find that fetal kick force increases significantly from 20 to 30 weeks' gestation, before decreasing towards term. However, stress and strain in the fetal skeleton rises significantly over the latter half of gestation. This increasing trend with gestational age is important because changes in fetal movement patterns in late pregnancy have been linked to poor fetal outcomes and musculoskeletal malformations. This research represents the first quantification of kick force and mechanical stress and strain due to fetal movements in the human skeleton in utero , thus advancing our understanding of the biomechanical environment of the uterus. Further, by revealing a potential link between fetal biomechanics and skeletal malformations, our work will stimulate future research in tissue engineering and mechanobiology.

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Rabbitt, R. D. « Semicircular canal biomechanics in health and disease ». Journal of Neurophysiology 121, n^o 3 (1 mars 2019) : 732–55. http://dx.doi.org/10.1152/jn.00708.2018.

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The semicircular canals are responsible for sensing angular head motion in three-dimensional space and for providing neural inputs to the central nervous system (CNS) essential for agile mobility, stable vision, and autonomic control of the cardiovascular and other gravity-sensitive systems. Sensation relies on fluid mechanics within the labyrinth to selectively convert angular head acceleration into sensory hair bundle displacements in each of three inner ear sensory organs. Canal afferent neurons encode the direction and time course of head movements over a broad range of movement frequencies and amplitudes. Disorders altering canal mechanics result in pathological inputs to the CNS, often leading to debilitating symptoms. Vestibular disorders and conditions with mechanical substrates include benign paroxysmal positional nystagmus, direction-changing positional nystagmus, alcohol positional nystagmus, caloric nystagmus, Tullio phenomena, and others. Here, the mechanics of angular motion transduction and how it contributes to neural encoding by the semicircular canals is reviewed in both health and disease.

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Salmond, Layne H., Andrew D. Davidson et Steven K. Charles. « Proximal-distal differences in movement smoothness reflect differences in biomechanics ». Journal of Neurophysiology 117, n^o 3 (1 mars 2017) : 1239–57. http://dx.doi.org/10.1152/jn.00712.2015.

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Smoothness is a hallmark of healthy movement. Past research indicates that smoothness may be a side product of a control strategy that minimizes error. However, this is not the only reason for smooth movements. Our musculoskeletal system itself contributes to movement smoothness: the mechanical impedance (inertia, damping, and stiffness) of our limbs and joints resists sudden change, resulting in a natural smoothing effect. How the biomechanics and neural control interact to result in an observed level of smoothness is not clear. The purpose of this study is to 1) characterize the smoothness of wrist rotations, 2) compare it with the smoothness of planar shoulder-elbow (reaching) movements, and 3) determine the cause of observed differences in smoothness. Ten healthy subjects performed wrist and reaching movements involving different targets, directions, and speeds. We found wrist movements to be significantly less smooth than reaching movements and to vary in smoothness with movement direction. To identify the causes underlying these observations, we tested a number of hypotheses involving differences in bandwidth, signal-dependent noise, speed, impedance anisotropy, and movement duration. Our simulations revealed that proximal-distal differences in smoothness reflect proximal-distal differences in biomechanics: the greater impedance of the shoulder-elbow filters neural noise more than the wrist. In contrast, differences in signal-dependent noise and speed were not sufficiently large to recreate the observed differences in smoothness. We also found that the variation in wrist movement smoothness with direction appear to be caused by, or at least correlated with, differences in movement duration, not impedance anisotropy. NEW & NOTEWORTHY This article presents the first thorough characterization of the smoothness of wrist rotations (flexion-extension and radial-ulnar deviation) and comparison with the smoothness of reaching (shoulder-elbow) movements. We found wrist rotations to be significantly less smooth than reaching movements and determined that this difference reflects proximal-distal differences in biomechanics: the greater impedance (inertia, damping, stiffness) of the shoulder-elbow filters noise in the command signal more than the impedance of the wrist.

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Lusiana. « The Biomechanic Of Bridge Up Analysis ». International Journal of Kinesiology and Physical Education 1, n^o 2 (24 décembre 2019) : 51–57. http://dx.doi.org/10.34004/ijkpe.v1i1.15.

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Sport is a physical activity to maintain physic fitness and health. Physical fitness can be obtained with correct physical activity, one of which is by doing gymnastic movements. Bridge up is one of the movements in gymnastics on the floor with a supine body shape or posture which rests on both hands and legs with knees bent. The correct movement is a movement that is in accordance with the anatomy and physiology of the human body, coupled with a mechanical study of efficient movement. In terms of biomechanics, the mechanical laws of motion are: 1) center of gravity, 2) balance and 3) force. It takes coordination between balance, flexibility and good strength to be able to make movement bridge up. Efforts to avoid mistakes that can result in injury can be done by applying the principles of proper training and adequate stretching. In the learning process, a teacher/lecturer must pay attention to the condition of students by providing step by step exercises or a series of movements from simple to complex.

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IVANCEVIC, VLADIMIR, et SANJEEV SHARMA. « COMPLEXITY IN HUMAN AND HUMANOID BIOMECHANICS ». International Journal of Humanoid Robotics 05, n^o 04 (décembre 2008) : 679–98. http://dx.doi.org/10.1142/s0219843608001571.

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We propose the following complexity conjecture: in a combined biomechanical system, where the action of Newtonian laws cannot be neglected, it is the mechanical part that determines the lower limit of complexity of the combined system, commonly defined as the number of mechanical degrees of freedom. The biological part of such a system, being "more intelligent", naturally serves as a "controller" for the "nonintelligent" mechanical "plant". Although, in some special cases, the behavior of the combined system might have a "simple" output, a realistic internal state space analysis shows that the total system complexity represents either the superposition, or a kind of "macroscopic entanglement" of the two partial complexities. Neither "mutual canceling" nor "averaging" of the mechanical degrees of freedom generally occurs in such a biomechanical system. The combined system has both dynamical and control complexities. The "realistic" computational model of such a system also has its own computational complexity. We demonstrate the validity of the above conjecture using the example of the physiologically realistic computer model. We further argue that human motion is the simplest well-defined example of a general human behavior, and discuss issues of simplicity versus predictability/controllability in complex systems. Further, we discuss self-assembly in relation to conditioned training in human/humanoid motion. It is argued that there is a significant difference in the observational resolution of human motion while one is watching "subtle" movements of a human hands playing a piano versus "coarse" movements of a human crowd at a football stadium from an orbital satellite. Techniques such as cellular automata can model the coarse crowd motion, but not the subtle hierarchical neural control of the dynamics of human hands playing a piano. Therefore, we propose the observational resolution as a new measure of biomechanical complexity. Finally, there is a possible route to apparent simplicity in biomechanics, in the form of oscillatory synchronization, both external (kinematical) and internal (control).

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POTKONJAK, VELJKO. « ROBOTIC HANDWRITING ». International Journal of Humanoid Robotics 02, n^o 01 (mars 2005) : 105–24. http://dx.doi.org/10.1142/s021984360500034x.

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Handwriting has always been considered an important human task, and accordingly it has attracted the attention of researchers working in biomechanics, physiology, and related fields. There exist a number of studies on this area. This paper considers the human–machine analogy and relates robots with handwriting. The work is two-fold: it improves the knowledge in biomechanics of handwriting, and introduces some new concepts in robot control. The idea is to find the biomechanical principles humans apply when resolving kinematic redundancy, express the principles by means of appropriate mathematical models, and then implement them in robots. This is a step forward in the generation of human-like motion of robots. Two approaches to redundancy resolution are described: (i) "Distributed Positioning" (DP) which is based on a model to represent arm motion in the absence of fatigue, and (ii) the "Robot Fatigue" approach, where robot movements similar to the movements of a human arm under muscle fatigue are generated. Both approaches are applied to a redundant anthropomorphic robot arm performing handwriting. The simulation study includes the issues of legibility and inclination of handwriting. The results demonstrate the suitability and effectiveness of both approaches.

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Astreinidi Blandin, Afroditi, Irene Bernardeschi et Lucia Beccai. « Biomechanics in Soft Mechanical Sensing : From Natural Case Studies to the Artificial World ». Biomimetics 3, n^o 4 (24 octobre 2018) : 32. http://dx.doi.org/10.3390/biomimetics3040032.

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Living beings use mechanical interaction with the environment to gather essential cues for implementing necessary movements and actions. This process is mediated by biomechanics, primarily of the sensory structures, meaning that, at first, mechanical stimuli are morphologically computed. In the present paper, we select and review cases of specialized sensory organs for mechanical sensing—from both the animal and plant kingdoms—that distribute their intelligence in both structure and materials. A focus is set on biomechanical aspects, such as morphology and material characteristics of the selected sensory organs, and on how their sensing function is affected by them in natural environments. In this route, examples of artificial sensors that implement these principles are provided, and/or ways in which they can be translated artificially are suggested. Following a biomimetic approach, our aim is to make a step towards creating a toolbox with general tailoring principles, based on mechanical aspects tuned repeatedly in nature, such as orientation, shape, distribution, materials, and micromechanics. These should be used for a future methodical design of novel soft sensing systems for soft robotics.

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Nishikawa, Kiisa C. « Neuromuscular control of prey capture in frogs ». Philosophical Transactions of the Royal Society of London. Series B : Biological Sciences 354, n^o 1385 (29 mai 1999) : 941–54. http://dx.doi.org/10.1098/rstb.1999.0445.

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While retaining a feeding apparatus that is surprisingly conservative morphologically, frogs as a group exhibit great variability in the biomechanics of tongue protraction during prey capture, which in turn is related to differences in neuromuscular control. In this paper, I address the following three questions. (1) How do frog tongues differ biomechanically? (2) What anatomical and physiological differences are responsible? (3) How is biomechanics related to mechanisms of neuromuscular control? Frog species use three non–exclusive mechanisms to protract their tongues during feeding: (i) mechanical pulling, in which the tongue shortens as its muscles contract during protraction; (ii) inertial elongation, in which the tongue lengthens under inertial and muscular loading; and (iii) hydrostatic elongation, in which the tongue lengthens under constraints imposed by the constant volume of a muscular hydrostat. Major differences among these functional types include (i) the amount and orientation of collagen fibres associated with the tongue muscles and the mechanical properties that this connective tissue confers to the tongue as a whole; and (ii) the transfer of inertia from the opening jaws to the tongue, which probably involves a catch mechanism that increases the acceleration achieved during mouth opening. The mechanisms of tongue protraction differ in the types of neural mechanisms that are used to control tongue movements, particularly in the relative importance of feed–forward versus feedback control, in requirements for precise interjoint coordination, in the size and number of motor units, and in the afferent pathways that are involved in coordinating tongue and jaw movements. Evolution of biomechanics and neuromuscular control of frog tongues provides an example in which neuromuscular control is finely tuned to the biomechanical constraints and opportunities provided by differences in morphological design among species.

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Ruellas, Antônio Carlos de Oliveira, Matheus Melo Pithon et Rogério Lacerda dos Santos. « Miniscrew-supported coil spring for molar uprighting : description ». Dental Press Journal of Orthodontics 18, n^o 1 (février 2013) : 45–49. http://dx.doi.org/10.1590/s2176-94512013000100012.

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INTRODUCTION: Since the beginning of miniscrews as orthodontic anchorage, many applications have been described in the literature. Among these, one is the uprighting of mesially inclined molars. In regard to the mechanical aspects, however, there is little information about the application of orthodontic forces using such devices. OBJECTIVE: The objective of this study was to describe a miniscrew supported spring for uprighting of mesially inclined molars. With this device, one can achieve the correct use of orthodontic biomechanics, thus favoring more predictable tooth movements and preventing unwanted movements from occurring.

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Andrysek, Jan, Daniela García, Claudio Rozbaczylo, Carlos Alvarez-Mitchell, Rebeca Valdebenito, Karin Rotter et F. Virginia Wright. « Biomechanical responses of young adults with unilateral transfemoral amputation using two types of mechanical stance control prosthetic knee joints ». Prosthetics and Orthotics International 44, n^o 5 (11 mai 2020) : 314–22. http://dx.doi.org/10.1177/0309364620916385.

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Background: Prosthetic knee joint function is important in the rehabilitation of individuals with transfemoral amputation. Objectives: The objective of this study was to assess the gait patterns associated with two types of mechanical stance control prosthetic knee joints—weight-activated braking knee and automatic stance-phase lock knee. It was hypothesized that biomechanical differences exist between the two knee types, including a prolonged swing-phase duration and exaggerated pelvic movements for the weight-activated braking knee during gait. Study design: Prospective crossover study. Methods: Spatiotemporal, kinematic, and kinetic parameters were obtained via instrumented gait analysis for 10 young adults with a unilateral transfemoral amputation. Discrete gait parameters were extracted based on their magnitudes and timing. Results: A 1.01% ± 1.14% longer swing-phase was found for the weight-activated braking knee (p < 0.05). The prosthetic ankle push-off also occurred earlier in the gait cycle for the weight-activated braking knee. Anterior pelvic tilt was 3.3 ± 3.0 degrees greater for the weight-activated braking knee. This range of motion was also higher (p < 0.05) and associated with greater hip flexion angles. Conclusions: Stance control affects biomechanics primarily in the early and late stance associated with prosthetic limb loading and unloading. The prolonged swing-phase time for the weight-activated braking knee may be associated with the need for knee unloading to initiate knee flexion during gait. The differences in pelvic tilt may be related to knee stability and possibly the different knee joint stance control mechanisms. Clinical relevance Understanding the influence of knee function on gait biomechanics is important in selecting and improving treatments and outcomes for individuals with lower-limb amputations. Weight-activated knee joints may result in undesired gait deviations associated with stability in early stance-phase, and swing-phase initiation in the late stance-phase of gait.

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Kodigepalli, Karthik M., Kaitlyn Thatcher, Toni West, Daniel P. Howsmon, Frederick J. Schoen, Michael S. Sacks, Christopher K. Breuer et Joy Lincoln. « Biology and Biomechanics of the Heart Valve Extracellular Matrix ». Journal of Cardiovascular Development and Disease 7, n^o 4 (16 décembre 2020) : 57. http://dx.doi.org/10.3390/jcdd7040057.

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Heart valves are dynamic structures that, in the average human, open and close over 100,000 times per day, and 3 × 109 times per lifetime to maintain unidirectional blood flow. Efficient, coordinated movement of the valve structures during the cardiac cycle is mediated by the intricate and sophisticated network of extracellular matrix (ECM) components that provide the necessary biomechanical properties to meet these mechanical demands. Organized in layers that accommodate passive functional movements of the valve leaflets, heart valve ECM is synthesized during embryonic development, and remodeled and maintained by resident cells throughout life. The failure of ECM organization compromises biomechanical function, and may lead to obstruction or leaking, which if left untreated can lead to heart failure. At present, effective treatment for heart valve dysfunction is limited and frequently ends with surgical repair or replacement, which comes with insuperable complications for many high-risk patients including aged and pediatric populations. Therefore, there is a critical need to fully appreciate the pathobiology of biomechanical valve failure in order to develop better, alternative therapies. To date, the majority of studies have focused on delineating valve disease mechanisms at the cellular level, namely the interstitial and endothelial lineages. However, less focus has been on the ECM, shown previously in other systems, to be a promising mechanism-inspired therapeutic target. Here, we highlight and review the biology and biomechanical contributions of key components of the heart valve ECM. Furthermore, we discuss how human diseases, including connective tissue disorders lead to aberrations in the abundance, organization and quality of these matrix proteins, resulting in instability of the valve infrastructure and gross functional impairment.

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Zhu, Zhiqiang, Weijie Fu, En Shao, Lu Li, Linjie Song, Wei Wang et Yu Liu. « Acute Effects of Midsole Bending Stiffness on Lower Extremity Biomechanics during Layup Jumps ». Applied Sciences 10, n^o 1 (5 janvier 2020) : 397. http://dx.doi.org/10.3390/app10010397.

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Purpose: This study aims to investigate the acute effects of shoe midsole stiffness on the joint biomechanics of the lower extremities during specific basketball movements. Methods: Thirty participants wearing stiff midsole shoes (SS) and control shoes (CS) performed layup jumps (LJs) while the kinematics and ground reaction forces were simultaneously collected via the Vicon motion capture system and Kistler force plates. Furthermore, the joint angles, range of motion (ROM), joint power, joint energy, and jump height were calculated. Results: No significant differences were observed between SS and CS conditions for both jump height and the metatarsophalangeal (MTP) joint biomechanics except that the minimum angular velocity of the MTP joint was significantly lower in SS the condition. However, the ROM in the ankle joint was significantly greater in the SS condition than in the CS condition (p < 0.05). Additionally, the maximum plantarflexion power, energy absorption (EA), and energy generation (EG) in the ankle joint were significantly greater in the SS condition than in the CS condition (p < 0.05). Compared with the CS condition, jump height in the SS condition did not increase. Conclusion: During a single LJ, the longitudinal midsole stiffness did not influence the jump height and MTP joint biomechanical patterns but significantly increased the maximum power, EA, and EG during the push-off phase of the ankle joint. These preliminary results indicate that wearing SS could change the ankle joint mechanical patterns by modulating the lower extremity kinetic chain, and may enhance muscle strength in the ankle.

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Windmill, James F. C., Joseph C. Jackson, Victoria G. Pook et Daniel Robert. « Frequency doubling by active in vivo motility of mechanosensory neurons in the mosquito ear ». Royal Society Open Science 5, n^o 1 (janvier 2018) : 171082. http://dx.doi.org/10.1098/rsos.171082.

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Across vertebrate and invertebrate species, nonlinear active mechanisms are employed to increase the sensitivity and acuity of hearing. In mosquitoes, the antennal hearing organs are known to use active force feedback to enhance auditory acuity to female generated sounds. This sophisticated form of signal processing involves active nonlinear events that are proposed to rely on the motile properties of mechanoreceptor neurons. The fundamental physical mechanism for active auditory mechanics is theorized to rely on a synchronization of motile neurons, with a characteristic frequency doubling of the force generated by an ensemble of motile mechanoreceptors. There is however no direct biomechanical evidence at the mechanoreceptor level, hindering further understanding of the fundamental mechanisms of sensitive hearing. Here, using in situ and in vivo atomic force microscopy, we measure and characterize the mechanical response of mechanosensory neuron units during forced oscillations of the hearing organ. Mechanoreceptor responses exhibit the hallmark of nonlinear feedback for force generation, with movements at twice the stimulus frequency, associated with auditory amplification. Simultaneous electrophysiological recordings exhibit similar response features, notably a frequency doubling of the firing rate. This evidence points to the nature of the mechanism, whereby active hearing in mosquitoes emerges from the double-frequency response of the auditory neurons. These results open up the opportunity to directly investigate active cellular mechanics in auditory systems, and they also reveal a pathway to study the nanoscale biomechanics and its dynamics of cells beyond the sense of hearing.

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Louder, Talin, Dennis Dolny et Eadric Bressel. « Biomechanical Comparison of Countermovement Jumps Performed on Land and in Water : Age Effects ». Journal of Sport Rehabilitation 27, n^o 3 (1 mai 2018) : 249–56. http://dx.doi.org/10.1123/jsr.2016-0225.

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Context:The aquatic environment provides a low-impact alternative to land-based exercise and rehabilitation in older adults.Objective:Evaluate the biomechanics of older adults and young adults performing jumping movements on land and in water.Design and Setting:Cross-sectional, mixed-factorial experiment; adjustable-depth pool at sports medicine research facility.Participants:Fifty-six young adults (age = 22.0 [3.9] y) and 12 healthy older adults (age = 57.3 [4.4] y).Interventions:Each participant performed 6 maximal effort countermovement jumps: 3 jumps were performed on land, and 3 other jumps were performed with participants immersed in chest-deep water.Main Outcome Measures:Using data from the amortization and propulsive phases of jumping, the authors computed the following kinetic and kinematic measures: peak and mean mechanical power, peak force, amortization time and rate, unweighting and propulsive times, and lower-extremity segment kinematics.Results:Mechanical power outputs were greater in younger adults (peak: 7322 [4035] W) versus older adults (peak: 5661.65 [2639.86] W) and for jumps performed in water (peak: 9387 [3981] W) versus on land (peak: 4545.84 [1356.53] W). Peak dorsiflexion velocities were greater for jumps performed in water (66 [34] deg/s) versus on land (4 [7] deg/s). The amortization rate was 26% greater in water versus on land. The amortization time was 20% longer in older adults versus young adults.Conclusions:Countermovement jumps performed in water are mechanically specific from those performed on land. Older adults jumped with longer unweighting times and increased mechanical power in water. These results suggest that aquatic-based exercise and rehabilitation programs that feature jumping movements may benefit older adults.

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Liu, Jun Qian. « Study on Knee Movement Mechanical Simulation in Basketball Shooting ». Applied Mechanics and Materials 536-537 (avril 2014) : 1351–54. http://dx.doi.org/10.4028/www.scientific.net/amm.536-537.1351.

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Application of sports biomechanics, sports biomechanics analyses of technical action shots, biomechanical characteristics obtained the basketball shooting skill and summarize the influencing factors of sports biomechanics shooting rate, especially for the shot before the body, lower limbs of each part of the action process were studied.

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Sandow, Michael J. « Computer Modelling of Wrist Biomechanics : Translation into Specific Tasks and Injuries ». Current Rheumatology Reviews 16, n^o 3 (22 septembre 2020) : 178–83. http://dx.doi.org/10.2174/1573397115666190119095311.

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Background: The carpus is a complicated and functionally challenged mechanical system, advancements in the understanding of which have been compromised by the recognition that there is no standard carpal mechanical system and no typical wrist. This paper covers components of a larger project that seeks to develop a kinetic model of wrist mechanics to allow reverse analysis of the specific biomechanical controls or rules of a specific patient’s carpus. Those rules, unique to each patient, could be used to create a forward synthesis mathematical model to reproduce the individual’s anatomical motion in a virtual environment. Objective and Methods: Based on the previous observations, the carpus essentially moves with only two degrees of freedom-pitch (flexion/extension) and yaw (radial deviation/ulnar deviation)-while largely preventing roll (pronation/supination). The objective of this paper is, therefore, to present the background and justification to support the rules-based motion (RBM) concept, which states that the motion of a mechanical system, such as the wrist, is the net interplay of four rules: morphology, constraint, interaction, and load. The stable central column theory (SCCT) of wrist mechanics applies the concept of RBM to the carpus, and by using a reverse engineering computational analysis model, a consistent pattern of isometric constraints was identified, creating a “two-gear four-bar” linkage. This study assessed the motion of the carpus using a 3D (three-dimensional) dynamic visualization model. The hypothesis was that the pattern and direction of motion of the proximal row and the distal row with respect to the immediately cephalad carpal bones or radius would be similar in all directions of wrist motion. To identify the unique motion segments, 3D models were created from five normal wrists that underwent CT scanning in multiple positions of radial and ulnar deviation as well as flexion and extension. Each carpal row (proximal and distal) was animated in a virtual environment with the cephalad carpal bones or radius held immobile. The rotational axis and position of each bone and each row were then compared in sagittal (flexion-extension) and coronal (radial and ulnar deviation) motion. Results: The carpus appeared to have only two degrees of freedom, and yet was stable in those arcs with the loads applied proximally in the forearm. The proximal row moved in a singular arc, but with a varying extent during sagittal and coronal motion. The isometric constraints were consistent in both directions. The distal row moved on an axis formed by a pivot joint laterally (between the trapezium and scaphoid) and a saddle joint medially (between hamate and triquetrum). The sagittal and coronal alignment of this axis changed as the proximal row moved. This created a distinct pattern of row motion to achieve the various required positions of wrist function. On wrist radial deviation, the scaphoid (with the proximal row) was flexed and the distal row was extended, whereas, in wrist flexion, the scaphoid flexed (with the proximal row) and so did the distal row. The pattern was reversed in the opposite wrist movements. While the general direction of motion of each row was consistent, the extent was quite variable. Conclusion: This review supports the SCCT of carpal mechanics and the carpus acting as a twogear four-bar linkage, as well as the concept of RBM as a means to understand the biomechanics of the wrist, and how this is translated into specific functional tasks. More sophisticated 3D modelling will be required to further understand the specifics of carpal motion; however, reverse engineering of the specific rules that define each individual wrist can also be applied to a mathematical model to provide a “what if” test of particular surgical interventions for a variety of wrist injuries. The use of quantitative 3D Computed Tomography Scan (CT) analysis, surgical planning and virtual surgical intervention allows potential surgical solutions to be applied to a computer model of an injured wrist to test the possible outcomes and prognosis of a proposed treatment.

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Munsch, Amanda E., Brian Pietrosimone et Jason R. Franz. « The effects of knee extensor moment biofeedback on gait biomechanics and quadriceps contractile behavior ». PeerJ 8 (8 juillet 2020) : e9509. http://dx.doi.org/10.7717/peerj.9509.

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Individuals with knee joint pathologies exhibit quadriceps dysfunction that, during walking, manifests as smaller peak knee extensor moment (pKEM) and reduced knee flexion excursion. These changes persist despite muscle strengthening and may alter stance phase knee joint loading considered relevant to osteoarthritis risk. Novel rehabilitation strategies that more directly augment quadriceps mechanical output during functional movements are needed to reduce this risk. As an important first step, we tested the efficacy of real-time biofeedback during walking to prescribe changes of ±20% and ±40% of normal walking pKEM values in 11 uninjured young adults. We simultaneously recorded knee joint kinematics, ground reaction forces, and, via ultrasound, vastus lateralis (VL) fascicle length change behavior. Participants successfully responded to real-time biofeedback and averaged up to 55% larger and 51% smaller than normal pKEM values with concomitant and potentially favorable changes in knee flexion excursion. While the VL muscle-tendon unit (MTU) lengthened, VL fascicles accommodated weight acceptance during walking largely through isometric, or even slight concentric, rather than eccentric action as is commonly presumed. Targeted pKEM biofeedback may be a useful rehabilitative and/or scientific tool to elicit desirable changes in knee joint biomechanics considered relevant to the development of osteoarthritis.

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Anderson, Philip S. L., et Mark W. Westneat. « A biomechanical model of feeding kinematics forDunkleosteus terrelli(Arthrodira, Placodermi) ». Paleobiology 35, n^o 2 (2009) : 251–69. http://dx.doi.org/10.1666/08011.1.

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Biomechanical models illustrate how the principles of physics and physiology determine function in organisms, allowing ecological inferences and functional predictions to be based on morphology. Dynamic lever and linkage models of the mechanisms of the jaw and skull during feeding in fishes predict function from morphology and have been used to compare the feeding biomechanics of diverse fish groups, including fossil taxa, and to test ideas in ecological morphology. Here we perform detailed computational modeling of the four-bar linkage mechanism in the skull and jaw systems ofDunkleosteus terrelli, using software that accepts landmark morphological data to simulate the movements and mechanics of the skull and jaws during prey capture. The linkage system is based on the quadrate and cranio-thoracic joints: Cranial elevation around the cranio-thoracic joint forces the quadrate joint forward, which, coupled with a jaw depressor muscle connecting the jaw to the thoracic shield, causes the jaw to rotate downward during skull expansion. Results show a high speed transmission for jaw opening, producing a rapid expansion phase similar to that in modern fishes that use suction during prey capture. During jaw closing, the model computes jaw and skull rotation and a series of mechanical metrics including effective mechanical advantage of the jaw lever and kinematic transmission of the skull linkage system. Estimates of muscle cross-sectional area based on the largest of five specimens analyzed allow the bite force and strike speed to be estimated. Jaw-closing muscles ofDunkleosteuspowered an extraordinarily strong bite, with an estimated maximal bite force of over 6000 N at the jaw tip and more than 7400 N at the rear dental plates, for a large individual (10 m total length). This bite force capability is among the most powerful bites in animals. The combination of rapid gape expansion and powerful bite meant thatDunkleosteus terrellicould both catch elusive prey and penetrate protective armor, allowing this apex predator to potentially eat anything in its ecosystem, including other placoderms.

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Zhu, Min, Kaiwen Zhang, Hirotaka Tao, Sevan Hopyan et Yu Sun. « Magnetic Micromanipulation for In Vivo Measurement of Stiffness Heterogeneity and Anisotropy in the Mouse Mandibular Arch ». Research 2020 (22 juin 2020) : 1–11. http://dx.doi.org/10.34133/2020/7914074.

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The mechanical properties of tissues are pivotal for morphogenesis and disease progression. Recent approaches have enabled measurements of the spatial distributions of viscoelastic properties among embryonic and pathological model systems and facilitated the generation of important hypotheses such as durotaxis and tissue-scale phase transition. There likely are many unexpected aspects of embryo biomechanics we have yet to discover which will change our views of mechanisms that govern development and disease. One area in the blind spot of even the most recent approaches to measuring tissue stiffness is the potentially anisotropic nature of that parameter. Here, we report a magnetic micromanipulation device that generates a uniform magnetic field gradient within a large workspace and permits measurement of the variation of tissue stiffness along three orthogonal axes. By applying the device to the organ-stage mouse embryo, we identify spatially heterogenous and directionally anisotropic stiffness within the mandibular arch. Those properties correspond to the domain of expression and the angular distribution of fibronectin and have potential implications for mechanisms that orient collective cell movements and shape tissues during development. Assessment of anisotropic properties extends the repertoire of current methods and will enable the generation and testing of hypotheses.

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Zhang, Bo. « Research on Biomechanical Simulation and Simulation of Badminton Splitting and Hanging Action Based on Edge Computing ». Mobile Information Systems 2021 (27 avril 2021) : 1–8. http://dx.doi.org/10.1155/2021/5527879.

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Sports biomechanics refers to the science of the laws of mechanical motion produced in the process of biological movement. Its essence is to systematically and digitally reconstruct the fundamental attributes and characteristics of motion. At present, the research of sports biomechanics mainly focuses on the theoretical research of basic aspects and lacks the new technology of sports biomechanics digital simulation innovation and data measurement. This article takes the badminton chopping action as the research object and carries out biomechanical simulation and simulation research with the help of edge computing and genetic algorithm. First of all, this paper constructs a badminton chopping and hanging action system framework based on edge computing, so as to facilitate simulation and improve data transmission efficiency. Secondly, genetic algorithm is used in biomechanics simulation and simulation optimization and data analysis process. System testing and simulation verify the excellent performance of the biomechanical simulation of badminton chopping and hanging action established in this paper. The research will provide a reference for the academic circles to explore the field of sports biomechanics.

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Carrero, W., M. Cerrolaza, J. Romero et J. Cedeño. « PHYSIOLOGICAL IN VIVO LOADING MEASURING IN ALVEOLAR DISTRACTION ». Biomedical Engineering : Applications, Basis and Communications 24, n^o 03 (juin 2012) : 275–84. http://dx.doi.org/10.4015/s101623721150058x.

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Loading evaluation in biomechanics is of the most concern if reliable results are expected. A key aspect in the mechanical design of an alveolar distractor is the accurate evaluation of physiological loading for computer simulation and effective modeling. Very few information and previous works are available about this subject. A stainless steel load cell with strain gauges has been developed and manufactured, in order to get accurate values of physiological loading. The cell was attached to splints, like those used in orthodontia. The load cell was calibrated and then an "in vivo" test was carried out on four partially-edentulous patients. Load digital registers were obtained for three cases in each patient: Tongue protrusion, lower or upper lips retraction and a combination of tongue and lips during the vocalization. Records show that it is possible to interpret quantitatively the load proportionality according to the tongue and lip physiological movements. From the loads magnitude differences in four patients, it can be observed that the morphological factor or occlusion differences affect both the loads size of the tongue protrusion muscles and lip retraction due to the orbicular muscles which can vary slightly or significantly. Further studies are been carried out by considering other kind of patients suffering different pathologies.

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Latash, Mark L. « Biomechanics as a window into the neural control of movement ». Journal of Human Kinetics 52, n^o 1 (1 septembre 2016) : 7–20. http://dx.doi.org/10.1515/hukin-2015-0190.

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Abstract Biomechanics and motor control are discussed as parts of a more general science, physics of living systems. Major problems of biomechanics deal with exact definition of variables and their experimental measurement. In motor control, major problems are associated with formulating currently unknown laws of nature specific for movements by biological objects. Mechanics-based hypotheses in motor control, such as those originating from notions of a generalized motor program and internal models, are non-physical. The famous problem of motor redundancy is wrongly formulated; it has to be replaced by the principle of abundance, which does not pose computational problems for the central nervous system. Biomechanical methods play a central role in motor control studies. This is illustrated with studies with the reconstruction of hypothetical control variables and those exploring motor synergies within the framework of the uncontrolled manifold hypothesis. Biomechanics and motor control have to merge into physics of living systems, and the earlier this process starts the better.

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Olberding, Jeffrey P., et Stephen M. Deban. « Thermal robustness of biomechanical processes ». Journal of Experimental Biology 224, n^o 1 (1 janvier 2021) : jeb228973. http://dx.doi.org/10.1242/jeb.228973.

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ABSTRACTTemperature influences many physiological processes that govern life as a result of the thermal sensitivity of chemical reactions. The repeated evolution of endothermy and widespread behavioral thermoregulation in animals highlight the importance of elevating tissue temperature to increase the rate of chemical processes. Yet, movement performance that is robust to changes in body temperature has been observed in numerous species. This thermally robust performance appears exceptional in light of the well-documented effects of temperature on muscle contractile properties, including shortening velocity, force, power and work. Here, we propose that the thermal robustness of movements in which mechanical processes replace or augment chemical processes is a general feature of any organismal system, spanning kingdoms. The use of recoiling elastic structures to power movement in place of direct muscle shortening is one of the most thoroughly studied mechanical processes; using these studies as a basis, we outline an analytical framework for detecting thermal robustness, relying on the comparison of temperature coefficients (Q10 values) between chemical and mechanical processes. We then highlight other biomechanical systems in which thermally robust performance that arises from mechanical processes may be identified using this framework. Studying diverse movements in the context of temperature will both reveal mechanisms underlying performance and allow the prediction of changes in performance in response to a changing thermal environment, thus deepening our understanding of the thermal ecology of many organisms.

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M.Asyraf, AH, AR Ahmad et GN Solayar. « Successful Outcome Following Bilateral Dual-Mobility Total Hip Arthroplasty For Neglected Developmental Dysplasia Of The Hip – A Case Report ». Orthopaedic Journal of Sports Medicine 8, n^o 5_suppl5 (1 mai 2020) : 2325967120S0002. http://dx.doi.org/10.1177/2325967120s00029.

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Objectives: Developmental dysplasia of hip (DDH) is a disorder of abnormal development of dislocation of hip secondary to casular laxity and mechanical factor. Arthroplasty maybe challenging with acetabular dysmorphia affecting cup placement which may increase the risk of dislocation post procedure Results: We describe a case of 60 years old lady that with history of difficulty in walking since childhood but not taken any definitive treatment. She presented with complaint of pain in both hips for last 5 years ago. On examination, patient was walking with waddling gait. All hip movements were painfully restricted. 3 cm shortening was present on left side. Radiological examination, Radiographs of the pelvis revealed proximally migrated dysplastic head of femur with dysplastic shallow empty acetabulum. Patient was underwent for right dual-mobility total hip arthroplasty (THA) first with acetabular shelf grafting. Following successful results, she opted for a similar implant on the left side. Harris Hip Score was used to evaluate the functional outcome of hip. Prior of operation, the score was 40, then after operation, the score was 80. The patient is currently two years from her surgery and ambulating with one stick Conclusion: In untreated developmental dysplasia of hip, concentric reduction of prosthetic hip is technically demanding. Cup coverage and restoration of normal hip biomechanics remain the most important issues. Acetabulum is hypoplastic with narrow femoral medullary canal. Dual-mobility arthroplasty is an option with potentially reduced wear rates and improved articulating stability; particularly in cases of DDH where placement maybe sub-optimally placed due to existing acetabular dysmorphia. This case highlights success in treating patients with DDH using dual-mobility arthroplasty. In untreated developmental dysplasia of hip, concentric reduction of prosthetic hip is technically demanding. Cup coverage and restoration of normal hip biomechanics remain the most important issues. Acetabulum is hypoplastic with narrow femoral medullary canal. Dual-mobility arthroplasty is an option with potentially reduced wear rates and improved articulating stability; particularly in cases of DDH where placement maybe sub-optimally placed due to existing acetabular dysmorphia. This case highlights success in treating patients with DDH using dual-mobility arthroplasty.

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Bertomeu-Motos, Arturo. « Biomechanics of human walking and stability descriptive parameters ». Revista Doctorado UMH 2, n^o 1 (16 mars 2016) : 4. http://dx.doi.org/10.21134/doctumh.v1i1.880.

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From the time of Aristotle onward, there have been countless books written on the topic of movement in animals and humans. However, research of human motion, especially walking mechanisms, has increased over the last fifty years. The study of human body movement and its stability during locomotion involves both neuronal and mechanical aspect. The mechanical aspect, which is in the scope of this thesis, requires knowledge in the field of biomechanics. Walking is the most common maneuver of displacement for humans and it is performed by a stable dynamic motion. In this article it is introduced the bases of the human walking in biomechanical terms. Furthermore, two stability descriptive parameters during walking are also explained - Center of Pressure (CoP) and Zero-Moment Pint (ZMP).

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Balardina, Andressa Lorandi, Simone Andrighettia, Vinícius Mazzochi Schimit, Fernanda Cechetti, Leandro Viçosa Bonetti et Raquel Saccani. « Análise Cinemática Linear e Angular da Marcha em Pacientes Amputados Transfemorais Protetizados ». Journal of Health Sciences 20, n^o 2 (27 juillet 2018) : 125. http://dx.doi.org/10.17921/2447-8938.2018v20n2p125-130.

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A amputação leva a uma série de alterações funcionais na biomecânica corporal, gerando padrões alterados de postura e de marcha para compensar a perda do membro, sendo possível através da análise cinemática identificar as compensações e adequar o padrão de marcha. O objetivo deste estudo foi identificar as alterações cinemáticas da marcha, em pacientes protetizados em nível transfemoral, considerando os valores da normalidade e do membro não afetado. Estudo descritivo, observacional, comparativo, transversal, no qual participaram 7 indivíduos, com idade média de 59 anos, com amputação transfemoral, já protetizados. Os pacientes foram selecionados na Clínica de Fisioterapia da Universidade de Caxias do Sul. Para análise da cinemática da marcha foi utilizado o Laboratório de Análises biomecânicas do Movimento Humano da Instituição, seguindo o protocolo descrito por Laroche. Para análise de dados foi utilizada a estatística descritiva e teste t pareado e one sample (p<0,05). Observaram-se inúmeras alterações na cinemática angular e linear destes indivíduos, tanto entre membros, quanto comparando com a normalidade, porém somente a flexão de quadril quando comparada com a normalidade mostrou diferença significativa estatística (p=0,009). O estudo indicou que existem alterações importantes na cinemática da marcha em amputados transfemorais comparando à normalidade e com o membro contralateral. Estas alterações podem estar relacionadas às questões de insegurança, falta de equilíbrio, propriocepção e instabilidade no membro afetado sobre a prótese, entre outros fatores musculoesqueléticos e biomecânicos ocasionados pela mudança do membro fisiológico pelo mecânico.Palavras-chave: Marcha. Amputação. Membros Artificiais.AbstractAmputation leads to a series of functional alterations on the corporal biomechanics and these generate altered posture patterns and the march as well. This is because it is necessary to compensate the loss of a limb. The objective of the study herein was to peform akinematic analysis to identify the compensation and to adequate the march pattern as well as the kinematic alterations of the march on prosthetic limb patients regarding transfemoral issues taking into account the values of normality and the non-affected limb. It was a descriptive , observational, comparative and transversal studies in which 7 people with an average age of 59 years old participated. These people are tranfemoral amputees and they are already prosthetic-limb users. The patients were selected at the Physiotherapy Clinic of the Universidade of Caxias do Sul. The kinematic analysis took place at the Laboratory of Biomechanics and Human Movements and the protocol described by Laroche was followed. The data analysis was based on the paired t- test and on the one sample (p<0,05). Various alterations were observed on angular and linear kinematic of these persons. These alterations were noted as much among members as when comparing to normality but only the hip flexion, when compared to normality, showed significant statistics (p= 0,009). The study indicated that there are important alterations in the kinematic march in trasfemoral amputees compared to normality and compared to the contralateral limb. These alterations might be associated with insecurity, lack of balance confidence, proprioception, and instability of the limb affected on the prosthesis among other skeletal muscle system and biomechanic factors caused by the replacement of the physiological member by the mechanical one.Keywords: Gait. Amputation. Artificial Limbs.

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Matsuoka, Yoky, Pedram Afshar et Michael Oh. « On the design of robotic hands for brain–machine interface ». Neurosurgical Focus 20, n^o 5 (mai 2006) : 1–9. http://dx.doi.org/10.3171/foc.2006.20.5.4.

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✓ Brain–machine interface (BMI) is the latest solution to a lack of control for paralyzed or prosthetic limbs. In this paper the authors focus on the design of anatomical robotic hands that use BMI as a critical intervention in restorative neurosurgery and they justify the requirement for lower-level neuromusculoskeletal details (relating to biomechanics, muscles, peripheral nerves, and some aspects of the spinal cord) in both mechanical and control systems. A person uses his or her hands for intimate contact and dexterous interactions with objects that require the user to control not only the finger endpoint locations but also the forces and the stiffness of the fingers. To recreate all of these human properties in a robotic hand, the most direct and perhaps the optimal approach is to duplicate the anatomical musculoskeletal structure. When a prosthetic hand is anatomically correct, the input to the device can come from the same neural signals that used to arrive at the muscles in the original hand. The more similar the mechanical structure of a prosthetic hand is to a human hand, the less learning time is required for the user to recreate dexterous behavior. In addition, removing some of the nonlinearity from the relationship between the cortical signals and the finger movements into the peripheral controls and hardware vastly simplifies the needed BMI algorithms. (Nonlinearity refers to a system of equations in which effects are not proportional to their causes. Such a system could be difficult or impossible to model.) Finally, if a prosthetic hand can be built so that it is anatomically correct, subcomponents could be integrated back into remaining portions of the user's hand at any transitional locations. In the near future, anatomically correct prosthetic hands could be used in restorative neurosurgery to satisfy the user's needs for both aesthetics and ease of control while also providing the highest possible degree of dexterity.

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Green, P. A., M. J. McHenry et A. Rico-Guevara. « Mechanoethology : The Physical Mechanisms of Behavior ». Integrative and Comparative Biology 61, n^o 2 (14 juin 2021) : 613–23. http://dx.doi.org/10.1093/icb/icab133.

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Abstract Research that integrates animal behavior theory with mechanics—including biomechanics, physiology, and functional morphology—can reveal how organisms accomplish tasks crucial to their fitness. Despite the insights that can be gained from this interdisciplinary approach, biomechanics commonly neglects a behavioral context and behavioral research generally does not consider mechanics. Here, we aim to encourage the study of “mechanoethology,” an area of investigation intended to encompass integrative studies of mechanics and behavior. Using examples from the literature, including papers in this issue, we show how these fields can influence each other in three ways: (1) the energy required to execute behaviors is driven by the kinematics of movement, and mechanistic studies of movement can benefit from consideration of its behavioral context; (2) mechanics sets physical limits on what behaviors organisms execute, while behavior influences ecological and evolutionary limits on mechanical systems; and (3) sensory behavior is underlain by the mechanics of sensory structures, and sensory systems guide whole-organism movement. These core concepts offer a foundation for mechanoethology research. However, future studies focused on merging behavior and mechanics may reveal other ways by which these fields are linked, leading to further insights in integrative organismal biology.

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Holt, Kenneth G., et Suh Fang Jeng. « Advances in Biomechanical Analysis of the Physically Challenged Child : Cerebral Palsy ». Pediatric Exercise Science 4, n^o 3 (août 1992) : 213–35. http://dx.doi.org/10.1123/pes.4.3.213.

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This paper presents some of the ways we are attempting to understand why physically challenged children adopt the movement patterns they do. It focuses on the skill of walking and compares non-neurologically disabled persons with children with cerebral palsy. A multidisciplinary approach is advocated in which the tools of biomechanics, physiology, and dynamical systems theory are explored. Traditional biomechanics of children with cerebral palsy tend to be descriptive in nature. More recent methods include both traditional biomechanical and dynamical systems approaches to understand why physically challenged children adopt the gait patterns they do. The concept of self-optimization is introduced as a way to motivate the investigations. Mechanical energy conservation, minimal metabolic cost, normality, and stability are discussed as some of the potential optimality criteria. Optimality criteria measurement including several methods of analysis of stability are discussed, and preliminary results of findings in the three groups are reported.

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Lam, Wing-Kai, Duo Wai-Chi Wong et Winson Chiu-Chun Lee. « Biomechanics of lower limb in badminton lunge : a systematic scoping review ». PeerJ 8 (4 novembre 2020) : e10300. http://dx.doi.org/10.7717/peerj.10300.

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Background Badminton is a popular sport activity in both recreational and elite levels. A lot of biomechanical studies have investigated badminton lunge, since good lunge performance may increase the chances to win the game. This review summarized the current trends, research methods, and parameters-of-interest concerning lower-extremity biomechanics in badminton lunges. Methodology Databases including Web of Science, Cochrane Library, Scopus, and PubMed were searched from the oldest available date to September 2020. Two independent authors screened all the articles and 20 articles were eligible for further review. The reviewed articles compared the differences among playing levels, footwear designs, and lunge directions/variations, using parameters including ground reaction forces, plantar pressure distribution, kinematics, and kinetics. Results Elite badminton players demonstrated higher impact attenuation capability, more aggressive knee and ankle strategy (higher mechanical moment), and higher medial plantar load than amateur players. Footwear modifications can influence comfort perception and movement mechanics, but it remains inconclusive regarding how these may link with lunging performance. Contradicting findings in kinematics is possibly due to the variations in lunge and instructions. Conclusions Playing levels and shoe designs have significant effects on biomechanics in badminton lunges. Future studies can consider to use an unanticipated testing protocol and realistic movement intensity. They can study the inter-limb coordination as well as the contributions and interactions of intrinsic and extrinsic factors to injury risk. Furthermore, current findings can stimulate further research studying whether some specific footwear materials with structural design could potentially compromise impact attenuation, proprioception, and performance.

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Prilutsky, Boris I., Mikhail G. Sirota, Robert J. Gregor et Irina N. Beloozerova. « Quantification of Motor Cortex Activity and Full-Body Biomechanics During Unconstrained Locomotion ». Journal of Neurophysiology 94, n^o 4 (octobre 2005) : 2959–69. http://dx.doi.org/10.1152/jn.00704.2004.

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Recent progress in the understanding of motor cortex function has been achieved primarily by simultaneously recording motor cortex neuron activity and the movement kinematics of the corresponding limb. We have expanded this approach by combining high-quality cortical single-unit activity recordings with synchronized recordings of full-body kinematics and kinetics in the freely behaving cat. The method is illustrated by selected results obtained from two cats tested while walking on a flat surface. Using this method, the activity of 43 pyramidal tract neurons (PTNs) was recorded, averaged over 10 bins of a locomotion cycle, and compared with full-body mechanics by means of principal component and multivariate linear regression analyses. Patterns of 24 PTNs (56%) and 219 biomechanical variables (73%) were classified into just four groups of inter-correlated variables that accounted for 91% of the total variance, indicating that many of the recorded variables had similar patterns. The ensemble activity of different groups of two to eight PTNs accurately predicted the 10-bin patterns of all biomechanical variables (neural decoding) and vice versa; different small groups of mechanical variables accurately predicted the 10-bin pattern of each PTN (neural encoding). We conclude that comparison of motor cortex activity with full-body biomechanics may be a useful tool in further elucidating the function of the motor cortex.

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Deda, Jakub, et Tomasz Mirosław. « Design of a mechanical knee joint for an exoskeleton ». MATEC Web of Conferences 338 (2021) : 01003. http://dx.doi.org/10.1051/matecconf/202133801003.

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The main problem of designing a lower limb exoskeleton for healthy people is allowing unconstrained movement along with providing sufficient load carrying capability. It is not a simple task since most of the human body joints have more than one degree of freedom. A designed mechanical equivalent should imitate these movements being outside the human body. Due to this, the mechanical joints must provide shortening or elongation of the structure during load carrying. Authors present biomechanical analyzes of a knee joint and propose a design of a mechanical equivalent of this joint that can be applied in exoskeletons. Additionally, laboratory trials proved suitability of this solution.

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Singh, Amit K., Sunil Prabhakar et Sanjay P. Sane. « The biomechanics of fast prey capture in aquatic bladderworts ». Biology Letters 7, n^o 4 (9 mars 2011) : 547–50. http://dx.doi.org/10.1098/rsbl.2011.0057.

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Carnivorous plants match their animal prey for speed of movements and hence offer fascinating insights into the evolution of fast movements in plants. Here, we describe the mechanics of prey capture in aquatic bladderworts Utricularia stellaris , which prey on swimming insect larvae or nematodes to supplement their nitrogen intake. The closed Utricularia bladder develops lower-than-ambient internal pressures by pumping out water from the bladder and thus setting up an elastic instability in bladder walls. When the external sensory trigger hairs on their trapdoor are mechanically stimulated by moving prey, the trapdoor opens within 300–700 μ s, causing strong inward flows that trap their prey. The opening time of the bladder trapdoor is faster than any recorded motion in carnivorous plants. Thus, Utricularia have evolved a unique biomechanical system to gain an advantage over their animal prey.

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Priego-Quesada, Jose I. « Exercise Biomechanics and Physiology ». Life 11, n^o 2 (19 février 2021) : 159. http://dx.doi.org/10.3390/life11020159.

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Khatib, N., C. Parisi et NC Nowlan. « Differential effect of frequency and duration of mechanical loading on fetal chick cartilage and bone development ». European Cells and Materials 41 (25 mai 2021) : 531–45. http://dx.doi.org/10.22203/ecm.v041a34.

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Developmental engineering strategies aim to recapitulate aspects of development in vitro as a means of forming functional engineered tissues, including cartilage and bone, for tissue repair and regeneration. Biophysical stimuli arising from fetal movements are critical for guiding skeletogenesis, but there have been few investigations of the biomechanical parameters which optimally promote cartilage and bone development events in in vitro explants. The effect of applied flexion-extension movement frequencies (0.33 and 0.67 Hz) and durations (2 h periods, 1, 2 or 3 × per day) on knee (stifle) joint cartilage shape, chondrogenesis and diaphyseal mineralisation of fetal chick hindlimbs, cultured in a mechanostimulation bioreactor, were assessed both quantitatively and qualitatively. It was hypothesised that increasing frequency and duration of movements would synergistically promote cartilage and bone formation in a dose-dependent manner. Increasing loading duration promoted cartilage growth, shape development and mineralisation of the femoral condyles and tibiotarsus. While increasing frequency had a significant positive effect on mineralisation, hyaline cartilage growth and joint shape were unaffected by frequency change within the ranges assessed, and there were limited statistical interactions between the effects of movement frequency and duration on cartilage or bone formation. Increased glycosaminoglycan deposition and cell proliferation may have contributed to the accelerated cartilage growth and shape change under increasing loading duration. The results demonstrated that frequencies and durations of applied biomechanical stimulation differentially promoted cartilage and bone formation, with implications for developmentally inspired tissue engineering strategies aiming to modulate tissue construct properties.

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Taha, Zahari, et Abdelhakim Deboucha. « Development of Synchronized Biomechanics Sensors Detection Software ». Advanced Materials Research 706-708 (juin 2013) : 771–75. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.771.

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Biomechanics is a relatively new discipline where engineering and mechanics principles are applied to the understanding of biological organism. Biomechanics simply taking place to study the mechanics of tissues, joints, human movements, circulatory system and digestive tract. One of the most challenging applications of biomechanics is in the field of sports and sports medicine in which the prevention of sports injuries is highly required. To understand and to diagnosis tissues abnormalities, mechanics of neuromuscular control, mechanics of cardiovascular function, a synchronizing interface with multi biomechanics sensors is developed in this effort. The interface shows different data recorded from several sensors during a physical activity made by the subject. These synchronized and combined data will help the user to make a specific diagnosis of the subject health. Moreover, these data will give an insight understanding on the correlation between variety aspects of biomechanics.

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Siri, Saeed, Yunmei Zhao, Franz Maier, David M. Pierce et Bin Feng. « The Macro- and Micro-Mechanics of the Colon and Rectum I : Experimental Evidence ». Bioengineering 7, n^o 4 (19 octobre 2020) : 130. http://dx.doi.org/10.3390/bioengineering7040130.

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Many lower gastrointestinal diseases are associated with altered mechanical movement and deformation of the large intestine, i.e., the colon and rectum. The leading reason for patients’ visits to gastrointestinal clinics is visceral pain, which is reliably evoked by mechanical distension rather than non-mechanical stimuli such as inflammation or heating. The macroscopic biomechanics of the large intestine were characterized by mechanical tests and the microscopic by imaging the load-bearing constituents, i.e., intestinal collagen and muscle fibers. Regions with high mechanical stresses in the large intestine (submucosa and muscularis propria) coincide with locations of submucosal and myenteric neural plexuses, indicating a functional interaction between intestinal structural biomechanics and enteric neurons. In this review, we systematically summarized experimental evidence on the macro- and micro-scale biomechanics of the colon and rectum in both health and disease. We reviewed the heterogeneous mechanical properties of the colon and rectum and surveyed the imaging methods applied to characterize collagen fibers in the intestinal wall. We also discussed the presence of extrinsic and intrinsic neural tissues within different layers of the colon and rectum. This review provides a foundation for further advancements in intestinal biomechanics by synergistically studying the interplay between tissue biomechanics and enteric neurons.

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Thibaut, Bernard. « Three-dimensional printing, muscles, and skeleton : mechanical functions of living wood ». Journal of Experimental Botany 70, n^o 14 (8 avril 2019) : 3453–66. http://dx.doi.org/10.1093/jxb/erz153.

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AbstractWood is well defined as an engineering material. However, living wood in the tree is often regarded only as a passive skeleton consisting of a sophisticated pipe system for the ascent of sap and a tree-like structure made of a complex material to resist external forces. There are two other active key roles of living wood in the field of biomechanics: (i) additive manufacturing of the whole structure by cell division and expansion, and (ii) a ‘muscle’ function of living fibres or tracheids generating forces at the sapwood periphery. The living skeleton representing most of the sapwood is a mere accumulation of dead tracheids and libriform fibres after their programmed cell death. It keeps a record of the two active roles of living wood in its structure, chemical composition, and state of residual stresses. Models and field experiments define four biomechanical traits based on stem geometry and parameters of wood properties resulting from additive manufacturing and force generation. Geometric parameters resulting from primary and secondary growth play the larger role. Passive wood properties are only secondary parameters, while dissymmetric force generation is key for movement, posture control, and tree reshaping after accidents.

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Hewett, Timothy E., Stephanie L. Di Stasi et Gregory D. Myer. « Current Concepts for Injury Prevention in Athletes After Anterior Cruciate Ligament Reconstruction ». American Journal of Sports Medicine 41, n^o 1 (5 octobre 2012) : 216–24. http://dx.doi.org/10.1177/0363546512459638.

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Ligament reconstruction is the current standard of care for active patients with an anterior cruciate ligament (ACL) rupture. Although the majority of ACL reconstruction (ACLR) surgeries successfully restore the mechanical stability of the injured knee, postsurgical outcomes remain widely varied. Less than half of athletes who undergo ACLR return to sport within the first year after surgery, and it is estimated that approximately 1 in 4 to 1 in 5 young, active athletes who undergo ACLR will go on to a second knee injury. The outcomes after a second knee injury and surgery are significantly less favorable than outcomes after primary injuries. As advances in graft reconstruction and fixation techniques have improved to consistently restore passive joint stability to the preinjury level, successful return to sport after ACLR appears to be predicated on numerous postsurgical factors. Importantly, a secondary ACL injury is most strongly related to modifiable postsurgical risk factors. Biomechanical abnormalities and movement asymmetries, which are more prevalent in this cohort than previously hypothesized, can persist despite high levels of functional performance, and also represent biomechanical and neuromuscular control deficits and imbalances that are strongly associated with secondary injury incidence. Decreased neuromuscular control and high-risk movement biomechanics, which appear to be heavily influenced by abnormal trunk and lower extremity movement patterns, not only predict first knee injury risk but also reinjury risk. These seminal findings indicate that abnormal movement biomechanics and neuromuscular control profiles are likely both residual to, and exacerbated by, the initial injury. Evidence-based medicine (EBM) strategies should be used to develop effective, efficacious interventions targeted to these impairments to optimize the safe return to high-risk activity. In this Current Concepts article, the authors present the latest evidence related to risk factors associated with ligament failure or a secondary (contralateral) injury in athletes who return to sport after ACLR. From these data, they propose an EBM paradigm shift in postoperative rehabilitation and return-to-sport training after ACLR that is focused on the resolution of neuromuscular deficits that commonly persist after surgical reconstruction and standard rehabilitation of athletes.

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Qin, Long, Qiao Wang, Dongliang Zhang, Xin He et Binbin Wu. « Optimized Attachment to Achieve Different Buccolingual Movement of Maxillary Molars in Clear Aligner Orthodontic System : Biomechanical Analysis ». Nanoscience and Nanotechnology Letters 12, n^o 11 (1 novembre 2020) : 1249–54. http://dx.doi.org/10.1166/nnl.2020.3151.

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The different positions and angles of attachment affecting the buccolingual movement of the maxillary molars, especially lingual tipping and negative torque movements, were biomechanically analyzed in order to determine how to better control and prevent unwanted movement of clear aligners. The aligner can be designed and placed appropriately to improve expected tooth movement. Based on mechanical principles, the force system of attachment was analyzed, and the optimum attachment position and angle for tipping and negative torque movement was determined. Attachment close to the enamel-cementum junction (ECJ) was found to achieve the best F (M/L) during negative torque movement; however, the angle should also be adjusted. Attachment close to the occlusal surface achieved greater tipping force at specific angles. When more tipping movement is required, it is recommended to place the attachment 3–5 mm from the ECJ. The angle of the attachment should be 110–120 degrees from the tooth surface. When place the attachment 4–5 mm from the ECJ, the angle of the attachment should be between 145 and 146.5 degrees.

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Chu, Shin Ying, et Steven M. Barlow. « Orofacial Biomechanics and Speech Motor Control ». Perspectives on Speech Science and Orofacial Disorders 19, n^o 1 (juillet 2009) : 37–43. http://dx.doi.org/10.1044/ssod19.1.37.

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Abstract The mechanical properties (e.g., mass, stiffness, viscoelasticity) of bone, cartilage, muscle, tendon, ligament, fat, and skin among articulatory subsystems involved in speech and gesture collectively influence all aspects of movement and must be accounted for in the selection and sequencing of motor program elements. Damage or disease processes affecting peripheral or central nervous system function, or both, can affect muscle coordination and alter muscle stiffness. Therefore, the biomechanics of orofacial and vocal tract structures should be taken into account when considering the movement patterns and network signaling in the neuromotor control system in health and disease. The purpose of this report is to summarize our evolving approach to and application of orofacial biomechanics in the context of movement disorders associated with dysarthria and craniofacial anomalies. We describe a new application for mapping stiffness in the lips for clinical application in pediatric and adult populations.

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Liu, Jin Song, et Ying Lu Jing. « Analysis and Training in Sanda Movement Rotor Inertia Biological Mechanics ». Advanced Materials Research 591-593 (novembre 2012) : 1996–99. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.1996.

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Applying the viewpoints and methods of sport biomechanics, and from the conservation of momentum, we have analysed Sanda rotation technique and elaborated on Sanda movement inertia mechanical characteristics and requirements, to make Sanda coaches and athletes on the basis of these laws of Sanda technique teaching and training, and to achieve the best results of training and sparring competition results.

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O’Brien, Thomas D. « Biomechanics and Exercise ». Pediatric Exercise Science 27, n^o 1 (février 2015) : 34–38. http://dx.doi.org/10.1123/pes.2015-0033.

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Children develop lower levels of muscle force, and at slower rates, than adults. While strength training in children is expected to reduce this differential, a synchronous adaptation in the tendon must be achieved to ensure forces continue to be transmitted to the skeleton with efficiency while minimizing the risk of strainrelated tendon injury. We hypothesized that resistance training (RT) would alter tendon mechanical properties in children concomitantly with changes in force production characteristics. Twenty prepubertal children (8.9 ± 0.3 years) were equally divided into control (nontraining) and experimental (training) groups. The training group completed a 10-week RT intervention consisting of 2-3 sets of 8-15 plantar flexion contractions performed twice weekly on a recumbent calf raise machine. Achilles tendon properties (cross-sectional area, elongation, stress, strain, stiffness and Young’s modulus), electromechanical delay (EMD; time between the onset of muscle activity and force), rate of force development (RFD; slope of the force-time curve) and rate of EMG increase (REI; slope of the EMG-time curve) were measured before and after RT. Tendon stiffness and Young’s modulus increased significantly after RT in the experimental group only (~29% and ~25%, respectively); all other tendon properties were not significantly altered, although there were mean decreases in both peak tendon strain and strain at a given force level (14% and 24%, respectively, n.s) which may have implications for tendon injury risk and muscle fiber mechanics. A ~13% decrease in EMD was found after RT for the experimental group which paralleled the increase in tendon stiffness (r = −0.59), however RFD and REI were unchanged. The present data show that the Achilles tendon adapts to RT in prepubertal children and is paralleled by a change in EMD, although the magnitude of this change did not appear to be sufficient to influence RFD. These findings are of potential importance within the context of the efficiency and execution of movement.

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Baseri, Amin, Mohammad Ali Bagheri, Gholamreza Rouhi, Mohammad Reza Aghighi et Nima Bagheri. « Fixation of distal tibia fracture through plating, nailing, and nailing with Poller screws : A comparative biomechanical-based experimental and numerical investigation ». Proceedings of the Institution of Mechanical Engineers, Part H : Journal of Engineering in Medicine 234, n^o 10 (10 juillet 2020) : 1129–38. http://dx.doi.org/10.1177/0954411920941664.

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The goal of this study was to investigate two commonly used methods of fixation of distal metaphyseal tibia fractures, plating and nailing as well as the less frequently employed nailing with Poller screws, from a biomechanical perspective. Despite numerous studies, the best method to repair fractures of tibia the remains up for of debate. This study includes an in vitro experimental phase on human cadaveric tibias followed by a finite element analysis. In the experimental phase, under partial weight-bearing axial loading, the axial stiffness of the bone-implant construct and interfragmentary movements for each of the fixation methods, bone-plate, bone-nail, and bone-nail-Poller screw, were measured and compared with each other. Shear interfragmentary movement and stress distribution in the bone-implant construct for the three mentioned fixation methods were also determined from FE models and compared with each other. Results of in vitro experiments, i.e., the exertion of axial loading on the tibia-plate, tibia-nail, and tibia-nail-Poller screw, showed that utilization of tibia-nail and tibia-nail-Poller screw led to a stiffer bone-implant construct, and consequently, lower interfragmentary movement, compared to the tibia-plate construct ( p values for tibia-nail and tibia-nail-Poller screw, and for both axial stiffness and interfragmentary movement, compared to those of tibia-plate construct, were less than 0.05). Numerical analyses showed that nailing produced less undesirable shear interfragmentary movement, compared to the plating, and application of a Poller screw decreased the shear movements, compared to tibia-nail. Furthermore, using the finite element analysis, maximum von Mises stress of adding a screw in tibia-nail, tibia-plate, and tibia-nail-Poller screw, was found to be: 51.5, 78.6, and 60.5 MPa, respectively. The results of this study suggested that from a biomechanical standpoint, nailing both with and without a Poller screw is superior to plating for the treatment of distal tibia fractures.

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Scott, Stephen H. « Role of motor cortex in coordinating multi-joint movements : Is it time for a new paradigm ? » Canadian Journal of Physiology and Pharmacology 78, n^o 11 (1 novembre 2000) : 923–33. http://dx.doi.org/10.1139/y00-064.

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Reaching movements to spatial targets require motor patterns at the shoulder to be coordinated carefully with those at the elbow to smoothly move the hand through space. While the motor cortex is involved in this volitional task, considerable debate remains about how this cortical region participates in planning and controlling movement. This article reviews two opposing interpretations of motor cortical function during multi-joint movements. On the one hand, studies performed predominantly on single-joint movement generally support the notion that motor cortical activity is intimately involved in generating motor patterns at a given joint. In contrast, studies on reaching demonstrate correlations between motor cortical activity and features of movement related to the hand, suggesting that the motor cortex may be involved in more global features of the task. Although this latter paradigm involves a multi-joint motor task in which neural activity is correlated with features of movement related to the hand, this neural activity is also correlated to other movement variables. Therefore it is difficult to assess if and how the motor cortex contributes to the coordination of motor patterns at different joints. In particular, present paradigms cannot assess whether motor cortical activity contributes to the control of one joint or multiple joints during whole-arm tasks. The final point discussed in this article is the development of a new experimental device (KINARM) that can both monitor and manipulate the mechanics of the shoulder and elbow independently during multi-joint motor tasks. It is hoped that this new device will provide a new approach for examining how the motor cortex is involved in motor coordination.Key words: reaching movements, biomechanics, motor coordination, proximal arm.

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Daniel, T. L., et M. S. Tu. « Animal movement, mechanical tuning and coupled systems ». Journal of Experimental Biology 202, n^o 23 (1 décembre 1999) : 3415–21. http://dx.doi.org/10.1242/jeb.202.23.3415.

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Over the past two decades, there has been a growing interest in developing predictive models of animal movement and force generation in fluids. In a departure from past studies that have asked how prescribed motions of a propulsor (wing or fin) generate lift and thrust during swimming and flying, we are increasingly interested in predicting the propulsor's movement as well as the forces generated by it. This interest, motivated by a need to understand the control and dynamics of locomotion and its applications to robotics and animal physiology, requires that we develop integrative models and analyses of swimming and flying that incorporate neural control and muscle physiology into more traditional biomechanical studies of locomotion in fluids. This approach extends from whole-animal studies to the molecular basis of force generation. In this paper, we explore mechanical tuning from the level of the whole animal to the proteins driving force generation in muscle.

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Moghimi, Negar, Sabrina Jedlicka et Svetlana Tatic-Lucic. « Micro-Electro-Mechanical System for Measuring Mechanical Properties of Cell Aggregates ». Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2015, DPC (1 janvier 2015) : 001701–20. http://dx.doi.org/10.4071/2015dpc-wp36.

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This paper presents design and finite element analysis (FEA) modeling of a novel micro-electro-mechanical system for determining mechanical properties of cell aggregates. The main components of this system are the electrostatic actuator array for applying force onto the cell aggregate and piezoresistive sensor for measuring it. A novel actuator array that allows for a set of five predefined displacements up to 100 μm was designed and modeled. FEA modeling of the components was performed to optimize the design and performance. While the device described is specifically designed for on-chip mechanical characterization of cell aggregates in vitro, it could also be translated to other applications. Application of MEMS in biomedical devices has expanded vastly over the last few decades. MEMS devices have been developed to measure different characteristics of cells. The study of cell biomechanics is of growing importance in biology and medical science, as mechanical properties of cells can be related to the cause, progress and cure of certain diseases [1]. The key motivation is to develop systems for controlled mechanical stimulation and characterization of cells. Previously we have developed BioMEM device for measuring mechanical characteristics of single cells [2]. Our new study is focused on a novel method to measure biomechanical properties of cell aggregates, which are commonly used in stem cell culture. The biomechanical measurement of cell aggregates could elucidate how cellular aggregates change with age, differentiation, and other cellular processes or states [3, 4]; which could further inform decisions regarding future use of the cells of interest. The actuation in this work is done by comb drive actuators [5] because of a relatively large displacement and independency of the electrostatic force from displacement. The springs need to be properly designed to achieve the maximum range of stable displacement. Folded flexure spring design combined with initially bent beams was used in our design because of great compliance in lateral direction, larger linear deflection range, lower side instability and minimal area usage [6, 7]. Coupled electromechanical modeling was performed to verify the actuator design. The actuator array consists of a central shuttle and five pairs of comb drives each provide different displacements ranging from 52 μm to 100 μm which correspond to 5 % to 25 % deformation of the targeted cell aggregate. Custom-designed springs that will support the central actuator shuttle and allow for the large displacements were designed and the ratio of shuttle stiffness in perpendicular direction to actuation direction was maximized in order to increase the stable range of shuttle forward movement. FEA of sensor part was also done to maximize the sensor sensitivity by modeling different designs with varied design parameters. This paper presents design of a novel MEMS actuator and sensor system. FEA modeling and optimization of device components was performed and the device is currently being fabricated.

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Wicaksono, Adhityo, Saifullah Hidayat, Bambang Retnoaji, Adolfo Rivero-Müller et Parvez Alam. « A mechanical piston action may assist pelvic–pectoral fin antagonism in tree-climbing fish ». Journal of the Marine Biological Association of the United Kingdom 98, n^o 8 (16 octobre 2017) : 2121–31. http://dx.doi.org/10.1017/s0025315417001722.

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In this research, we compared the anatomy and biomechanics of two species of mudskipper vs an aquatic sandgoby in view of terrestrial locomotion. Of particular interest was the relationship (if any) of pectoral fin movement with pelvic fin movement. We show that the pelvic fins of the terrestrial mudskippers studied herein, are retractable and move antagonistically with the pectoral fins. The pelvic fin of the sandgoby studied here is contrarily non-retractable and drags on any underlying substrate that the sandgoby tries to crawl across. We find that the pelvic and pectoral fin muscles of all fish are separated, but that the pectoral fins of the mudskipper species have bulkier radial muscles than the sandgoby. By coupling a detailed morphological investigation of pectoral-pelvic fins musculature with finite element simulations, we find that unlike sandgobies, the mudskipper species are able to mechanically push the pelvic fins downward as pectoral fins retract. This allows for an instant movement of pelvic fins during the pectoral fin backward stroke and as such the pelvic fins stabilize mudskippers through Stefan attachment of their pelvic fins. This mechanism seems to be efficient and energy saving and we hypothesize that the piston-like action might benefit pelvic–pectoral fin antagonism by facilitating a mechanical down-thrust. Our research on the biomechanics of tree-climbing fish provides ideas and greater potential for the development of energetically more efficient systems of ambulation in biomimetic robots.

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Wanless, Stephen. « Principles for the Safe Moving and Handling of Patients ». Pielegniarstwo XXI wieku / Nursing in the 21st Century 15, n^o 4 (1 décembre 2016) : 66–69. http://dx.doi.org/10.1515/pielxxiw-2016-0040.

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Abstract Human movement when walking or running is a widely researched area. However, there is an increased incidence of musculoskeletal injury from poor positioning when moving and handling patients amongst healthcare professionals and is one of the main causes of long term musculoskeletal health problems. In the clinical area, an individual’s musculoskeletal health system is subjected to mechanical loading, increasing the body’s stress and strain limits, and once these are exceeded injury occurs. The risk of pain and injury has a direct relation from the over use of poor posture from poor moving and handling, which in turn can cause loss of strength and reduce musculoskeletal function. This can be changed through healthcare workers adopting safe biomechanical body movements during patient handling tasks.

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