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Low-velocity motor vehicle crashes frequently induce chronic neck disorders also referred to as whiplash-associated disorders (WAD). The etiology of WAD is still not fully understood. Women are affected more often and more severely than men. A frontal-oblique collision direction leads to WAD relatively frequently, but is poorly investigated as compared to rear-end or frontal collision directions. An oblique impact direction is assumed to strain the contralateral neck side more than the ipsilateral side, provoking an asymmetrical response pattern of the left and right cervical muscles. In this study, we examined the muscle reflex responses of the sternocleidomastoid, the paraspinal, and the trapezius muscles as well as the kinematic responses of 60 subjects during left-frontal-oblique collisions. Neither the reflex delay nor the peak head acceleration revealed significant sex differences. Thus, the elsewhere reported higher injury risk of females as compared to males cannot be explained by the electromyographic and kinematic results of this study. In females as well as in males the right muscle responses revealed shorter onset times than the left muscle responses. Thus, cervical muscles seem to be activated depending on the specific direction of the impact. Moreover, the difference between right and left muscle responses cannot be explained by a startle reflex. The movement of the head in relation to the torso (female mean ± SD: 92 ± 16 ms; male: 87 ± 16 ms) started almost simultaneously to the onset of the first muscle activation (right paraspinal muscles: female mean: 95 ms and 95%-CI 82 − 109; male mean: 95 ms and 95%-CI 84 − 108) indicating that the initial muscle activity seems not to be triggered by a stretch reflex in the PARA muscles.

In motion analysis marker sets or protocols are mostly developed for gait analysis and it has been shown that the marker set used affects the results of gait analysis. These marker sets are also used for the analysis of high dynamic sports movements. Single-leg landings are a common tool to investigate functional knee stability and further to predict injury risks where frontal plane motion and loading seem to play an important role. Until now, it is unknown how the marker sets affect the motion analysis results of such high dynamic movements. Therefore, the aim of the study was to compare six different marker sets. Three-dimensional motion and force data of single-leg landings in 12 healthy subjects were collected. Six different marker sets consisting of up to 26 markers and two clusters were simultaneously attached to the subjects’ lower limb and pelvis. The results show that particularly, the knee joint angles in the frontal and transverse plane showed the greatest differences between marker sets with in part contrary joint angle directions and great differences in angle magnitude. In addition, the amount of joint load was dependent on the marker set used for analysis. These results show that one must be careful when interpreting and comparing data of the frontal or transverse plane during high dynamic movements.

Background Lumbar multifidus (LM) is regarded as the major stabilizing muscle of the spine. The effects of exercise therapy in low back pain (LBP) are attributed to this muscle. A current literature review is warranted, however, given the complexity of LM morphology and the inconsistency of anatomical descriptions in the literature. Methods Scoping review of studies on LM morphology including major anatomy atlases. All relevant studies were searched in PubMed (Medline) and EMBASE until June 2019. Anatomy atlases were retrieved from multiple university libraries and online. All studies and atlases were screened for the following LM parameters: location, imaging methods, spine levels, muscle trajectory, muscle thickness, cross-sectional area, and diameter. The quality of the studies and atlases was also assessed using a five-item evaluation system. Results In all, 303 studies and 19 anatomy atlases were included in this review. In most studies, LM morphology was determined by MRI, ultrasound imaging, or drawings – particularly for levels L4–S1. In 153 studies, LM is described as a superficial muscle only, in 72 studies as a deep muscle only, and in 35 studies as both superficial and deep. Anatomy atlases predominantly depict LM as a deep muscle covered by the erector spinae and thoracolumbar fascia. About 42% of the studies had high quality scores, with 39% having moderate scores and 19% having low scores. The quality of figures in anatomy atlases was ranked as high in one atlas, moderate in 15 atlases, and low in 3 atlases. Discussion Anatomical studies of LM exhibit inconsistent findings, describing its location as superficial (50%), deep (25%), or both (12%). This is in sharp contrast to anatomy atlases, which depict LM predominantly as deep muscle. Within the limitations of the self-developed quality-assessment tool, high-quality scores were identified in a majority of studies (42%), but in only one anatomy atlas. Conclusions We identified a lack of standardization in the depiction and description of LM morphology. This could affect the precise understanding of its role in background and therapy in LBP patients. Standardization of research methodology on LM morphology is recommended. Anatomy atlases should be updated on LM morphology.

Free, 3-D interceptive movements are difficult to visualize and quantify. For ball catching, the endpoint of a movement can be anywhere along the target's trajectory. Furthermore, the hand may already have begun to move before the subject has estimated the target's trajectory, and the subject may alter the targeted position during the initial part of the movement. We introduce a method to deal with these difficulties and to quantify three movement phases involved in catching: the initial, non-goal-directed phase; the goal-directed phase, which is smoothly directed toward the target's trajectory; and the final, interception phase. Therefore, the 3-D movement of the hand was decomposed into a component toward the target's trajectory (the minimal distance of the hand to the target's parabolic [MDHP] trajectory) and a component along this trajectory. To identify the goal-directed phase of the MDHP trajectory, we employed the empirical finding that goal-directed trajectories are minimally jerky. The second component, along the target's trajectory, was used to analyze the interaction of the hand with the ball. The method was applied to two conditions of a ball-catching task. In the manipulated condition, the initial part of the ball's flight was occluded, so the visibility of the ball was postponed. As expected, the onset of the smooth part of the movement shifted to a later time. This method can be used to quantify anticipatory behavior in interceptive tasks, allowing researchers to gain new insights into movement planning toward the target's trajectory.

A considerable body of work has examined the dynamics of different dog gaits, but there are no studies that focused on limb dynamics in jumping. Jumping is an essential part of dog agility, a dog sport in which handlers direct their dogs through an obstacle course in a limited time. We hypothesized that limb parameters like limb length and stiffness indicate the skill level of dogs. We analyzed global limb parameters in jumping for 10 advanced and 10 beginner dogs. In experiments, we collected 3D kinematics and ground reaction forces during dog jumping at high forward speeds. Our results revealed general strategies of limb control in jumping and highlighted differences between advanced and beginner dogs. In take-off, the spatially leading forelimb was 75% (p

The aim of the study was to assess the effects of muscle responses on the trunk motions during repeated perturbations by external forces. Patients with low back pain have delayed muscle reflex latencies to perturbations compared with healthy controls. The perturbation provoked trunk accelerations were simulated by a model consisting of four rigid bodies and six force elements representing trunk and hip muscles. The influence of the muscle responses were assessed by varying the reflex delays, the reflex durations, and the reflex gains. Trunk accelerations can be reduced by the simulated muscle responses. The optimal solution is not the result of extreme values of the reflex delay and duration range but of intermediate values. The relationship between the trunk accelerations and the reflex delay and duration respectively can be described by asymmetrical u-shape functions. As patients with low back pain showed delayed reflexes, their trunk motions are probably increased compared with healthy subjects.

Using recent recurrent network architecture based on the reservoir computing approach, we propose and numerically simulate a model that is focused on the aspects of a flexible motor memory for the storage of elementary movement patterns into the synaptic weights of a neural network, so that the patterns can be retrieved at any time by simple static commands. The resulting motor memory is flexible in that it is capable to continuously modulate the stored patterns. The modulation consists in an approximately linear inter- and extrapolation, generating a large space of possible movements that have not been learned before. A recurrent network of thousand neurons is trained in a manner that corresponds to a realistic exercising scenario, with experimentally measured muscular activations and with kinetic data representing proprioceptive feedback. The network is "self-active" in that it maintains recurrent flow of activation even in the absence of input, a feature that resembles the "resting-state activity" found in the human and animal brain. The model involves the concept of "neural outsourcing" which amounts to the permanent shifting of computational load from higher to lower-level neural structures, which might help to explain why humans are able to execute learned skills in a fluent and flexible manner without the need for attention to the details of the movement.

During pregnancy approximately 50% of women suffer from low back pain (LBP), which significantly affects their everyday life. The pain could result in chronic insomnia, limit the pregnant women in their ability to work and produce a reduction of their physical activity. The etiology of the pain is still critically discussed and not entirely understood. In the literature different explanations for LBP are given and one of the most common reasons is the anatomical changes of the female body during pregnancy; for instance, there is an increase in the sagittal moments because of the enlarged uterus and fetus and the occurrence of hyperlordosis.The aim of this study was to describe how the anatomical changes in pregnant women affect the stability and the moments acting on the lumbar spine with the help of a simplified musculoskeletal model.A two-dimensional musculoskeletal model of the lumbar spine in the sagittal plane consisting of five lumbar vertebrae was developed. The model included five centres of rotation and three antagonistic pairs of paraspinal muscles. The concept of altered acting torques during pregnancy was explored by varying the geometrical arrangements. The situations non-pregnant, pregnant and pregnant with hyperlordosis were considered for the model-based approach. These simulations were done dependent on the stability of the erect posture and local countertorques of every lumbar segment.In spite of the simplicity of the model and the musculoskeletal arrangement it was possible to maintain equilibrium of the erect posture at every lumbar spinal segment with one minimum physiological cross-sectional area of all paraspinal muscles. The stability of the musculoskeletal system depends on the muscular activity of the paraspinal muscles and diminishing the muscular activity causes unstable lumbar segments.The relationship between the non-pregnant and the pregnant simulations demonstrated a considerable increase of acting segmental countertorques. Simulating an increased lordosis for the pregnant situation in the sagittal plane substantially reduced these acting countertorques and therefore the demand on the segmental muscles.It is assumed that hyperlordosis is a physiological adaptation to the anatomical changes during pregnancy to minimize the segmental countertorques and therefore the demand on the segmental muscles.Further, it can be expected that an enhanced muscle activity caused by selective activity of lumbar muscles increases the stability of the lumbar spine and may improve the situation with LBP during pregnancy.

Ziel der Studie war die Untersuchung der posturalen Kontrolle wahrend externer uber die Fuse eingeleiteter Storungen bei Patienten mit chronischem nichtspezifischem Ruckenschmerz (CNRS). Zudem wurde der Einfluss der visuellen Information (Augen offen vs. Augen geschlossen) auf die posturale Kontrolle untersucht. Es wurden 8 Patienten mit CNRS (Alter: 40±12 Jahre; Body Mass Index, BMI: 23±2 kg/m2) ohne degenerative Bandscheibenerkrankung der Wirbelsaule (Befund der Magnetresonanztomografie) und 12 gesunde Vergleichspersonen (Alter: 28±7 Jahre; BMI: 21±3 kg/m2) untersucht. Mittels Oberflachenelektromyografie (OEMG) wurde die posturale Kontrolle bei 5 Rumpf- und 5 Beinmuskeln sowie einem Beckenmuskel bei distalen lateralen Storungen analysiert. Gesunde (Mittelwert ± Standardabweichung: 96,42±64,77 µV) zeigten im Vergleich zu Patienten mit CNRS (56,29±39,63 µV) eine signifikant (F=6,00; p

Der chronische unspezifische Ruckenschmerz ist ein zentrales Thema fur Patienten, Versicherer und Berufsgenossenschaften. Mit einer Praventivdiagnostik bestunde die Moglichkeit, fur einen momentan beschwerdefreien Menschen eine Prognose zu erstellen, mit welcher Wahrscheinlichkeit er einen chronischen unspezifischen Ruckenschmerz erleiden wird, wenn er sich nicht einer praventiven Masnahme unterzieht. Jedes Jahr erleiden 20% der Erwachsenen Ruckenschmerzen und 70–80% der Bevolkerung bekommen in ihrem Leben einmal oder mehrmals Ruckenschmerzen. Meist reduzieren sich die Beschwerden innerhalb der ersten sechs Wochen ohne medizinische Intervention oder verschwinden ganz. Nur in wenigen Fallen sind sie progredient, chronifizieren und verursachen erhebliche Kosten. Es gilt herauszufinden, ob eine Person zu einer Risikogruppe gezahlt werden kann, fur die zukunftig eine Chronifizierung des Ruckenschmerzes wahrscheinlich wird. Mit dem praventivdiagnostischen Ansatz sollte die Frage beantwortet werden konnen: Welche Subgruppe von Patienten mit chronischem Ruckenschmerz wird besonders von einer Ubungstherapie oder von kognitiven verhaltenstherapeutischen Ansatzen profitieren?

Both sensory information and mechanical properties of the musculoskeletal system are necessary for fast and appropriate reactions of humans and animals to environmental perturbations. In this paper, we focus on the musculoskeletal system and study the stability of a human elbow in an equilibrium state. We derive a biomechanical model of the human elbow, including an antagonistic pair of muscles, and investigate the stability analytically based on the theory of Ljapunov. Depending on the elbow angle and the level of coactivation, we obtain the following three qualitatively different behaviors: unstable, stable with real eigenvalues, and stable with complex eigenvalues. If the eigenvalues are real, then the system is critically damped; for complex eigenvalues, solutions near the equilibrium are oscillating. Based on experimental data, we found that in principle real and complex behaviors may occur in human arm movements. The experiments support the analytical predictions. Furthermore, in agreement with the simulations, we found differences in the experimental results among the subjects. The results of this study support the assumption that arm movements around an equilibrium point may be self-stabilized without sensory feedback or motor control, based only on mechanical properties of musculoskeletal systems.

For decades, the biomechanical description of quiet human stance has been dominated by the single inverted pendulum (SIP) paradigm. However, in the past few years, the SIP model family has been falsified as an explanatory approach. Double inverted pendulum models have recently proven to be inappropriate. Human topology with three major leg joints suggests in a natural way to examine triple inverted pendulum (TIP) models as an appropriate approach. In this study, we focused on formulating a TIP model that can synthesise stable balancing attractors based on minimalistic sensor information and actuation complexity. The simulated TIP oscillation amplitudes are realistic in vertical direction. Along with the horizontal ankle, knee and hip positions, though, all simulated joint angle amplitudes still exceed the measured ones about threefold. It is likely that they could be eventually brought down to the physiological range by using more sensor information. The TIP systems' eigenfrequency spectra come out as another major result. The eigenfrequencies spread across about 0.1 Hz...20 Hz. Our main result is that joint stiffnesses can be reduced even below statically required values by using an active hip torque balancing strategy. When reducing mono- and bi-articular stiffnesses further down to levels threatening dynamic stability, the spectra indicate a change from torus-like (stable) to strange (chaotic) attractors. Spectra of measured ground reaction forces appear to be strange-attractor-like. We would conclude that TIP models are a suitable starting point to examine more deeply the dynamic character of and the essential structural properties behind quiet human stance. Abbreviations and technical terms Inverted pendulum body exposed to gravity and pivoting in a joint around position of unstable equilibrium (operating point) SIP single inverted pendulum: one rigid body pivoting around fixation to the ground (external joint) DIP double inverted pendulum: two bodies; external and internal joint operate around instability TIP triple inverted pendulum: three bodies; external and both internal joints operate around instability QIP quadruple inverted pendulum: four bodies, foot replaces external joint; all three internal joints operate around instability Eigenfrequency characteristic frequency that a physical system is oscillating at when externally excited at a limited energy level DOF degree of freedom; in mechanics: linear displacement or angle or combination thereof Mono-articular stiffness: coefficient of proportionality between mechanical displacement of a DOF and restoring force/torque component in the respective DOF Bi-articular stiffness coefficient of proportionality between mechanical displacement of a DOF and restoring force/torque component in another DOF GRF ground reaction force HAT segment including head, arms and trunk COM centre of mass COP centre of pressure in the plane of the force platform surface.

Low back pain costs billions of Euros annually in all industrialized countries. Often radiological diagnosis fails to give evidence of the pathogenesis of low back pain. Although psychophysiological characteristics have an influence, it seems that insufficient muscular spinal stabilization may play the major role in the development of low back pain. Assessment of trunk muscle stabilization activity during everyday activities is rare. Therefore, in this study healthy persons were investigated during walking on a treadmill at a speed of 4 km/h. Women (n = 16) with no history of back pain were investigated before and after a static loading situation of the spine, i.e. while wearing a waistcoat. After this loading situation four women developed pain (pain subjects). Surface EMG (SEMG) was taken from five trunk muscles of both sides. Grand averaged amplitude curves over stride, amplitude normalized curves and variation between all included strides were calculated for all muscles and subjects, respectively. The normal range of all calculated parameters was defined within the span between the 5th and the 95th percentiles of all pain free subjects. Data were evaluated according to deviations from the normal range. Already before the load situation, pain subjects showed considerable deviations from the normal range, mainly of their abdominal muscles. There was no relationship between magnitude of deviation and pain intensity, but perceived exertion was highest in those subjects who showed the most symptoms in terms of number of muscles being identified as considerably deviating from the normal range. No specific "dysfunction pattern" could be identified, which argues for highly individual mechanisms instead of a single target muscle. The results suggest cumulative effects of different disturbance levels resulting in acute back pain. Since deviations could be identified already before the pain occurred, disturbed muscle function seems to be a risk factor for developing back pain. Further investigations aimed at clear identification of and, as a second step, correction of muscle function are necessary.

There are a lot of in vitro and also in vivo studies under strictly restricted and subject-demanding laboratory conditions using X-ray or MRI recordings, but very few studies give information about the lumbar spine intersegmental behavior in daily life activities. Aims of this study were to measure the intersegmental lumbar spine motions during lifting trials and to determine the different motion patterns of different subjects performing comparable lifting tasks. First, 11 healthy volunteers had to perform lifting tasks (box weight 4–15kg) using their favorite lifting technique (no instructions by the researcher). The coordinates of skin-markers attached on lumbar spines of the subjects were measured using 3D-motion capturing and then transformed to Cardan-angles. Second, 23 volunteers performed lifting tasks (box weight 4–15kg) with the instruction to bend their knees during lifting. Coordinates of this smaller set of markers on lumbar spines of the subjects were transformed to intersegmental angles using a spline-method. From the first experiment three groups of motion patterns are distinguishable: subjects who used only small intersegmental range of motion within their upper lumbar spine and bended their knees during lifting were in contrast to subjects who used 3.25 times wider range of motion in the upper lumbar spine and did not bend the knees (cluster analysis, c =0.76). The third group was not assignable to these other two groups. Within all lifting trials of the second experiment different groups were detectable also: in spite of all subjects bended their knees, there were subjects with wide range of motion of lumbar spine motion segments. Other subjects were able to reduce intersegmental range of motion ( k -means clustering, msv>0.47). From this it follows that the intersegmental motion of lumbar spine is individually different and not equal for all lumbar levels. Furthermore, lifting technique influenced the motion of the lumbar spine. But not for all subjects, the advice to bend the knees during the lifting effectively reduced the lumbar motion ranges. In conclusion: special instructions to reduce lumbar spinal motion are recommended. Due to different lumbar spine motion patterns, different loading situations are anticipated because of changing lever arms and angular accelerations. This understanding is important in reducing spinal loading and to prevent spinal disorders in manual material handling tasks.

Quick-release experiments often produce noticeable oscillations on the measured force and length data in the first few milliseconds after the force release. We measured oscillations in experiments with several species (Rattus norvegicus, Galea musteloides, Rana pipiens) and different experimental setups. These oscillations are generally ignored as artifacts.This study investigates the cause of the oscillations. A biomechanical model of the experimental setup was developed consisting of a geometric model describing the setup and a Hill-type muscle-tendon model including the force-length-velocity relation and a linear spring in series. Muscle properties of each muscle were determined by the ISOFIT method. Model calculations and forward simulations of quick-release experiments based on experimentally determined muscle properties reveal that the observed oscillations are not artifacts (instrument and control), but the result of interactions of muscle-tendon properties with the inertia of muscles, bones and lever system.

Background Activation of the deep stabilizing trunk muscle transversus abdominis (TrA) is important for trunk stabilization and spine stability. Sling exercises are used for the activation of trunk muscles, therefore we determined the thickness of the TrA in a standardized sling exercise in comparison to rest and abdominal press. Furthermore we propose a standardized measurement method, which can be used to compare relative muscle thickness levels in different exercises. Methods The main objective of the study was to assess and to compare the thickness of the TrA during different conditions; resting condition, sling exercise condition (non-voluntary contraction), and abdominal press condition (voluntary contraction) using a non-invasive ultrasound-based measurement method. Ultrasound measurement (USM; 8.9 MHz, B-mode) was employed to measure the thickness of the TrA in twenty healthy volunteers (13 m, 7 f), each one measured three times with breaks of 48 h. On each measurement day, the subjects were measured on three different conditions: resting condition (RC), sling condition (SC), and abdominal press condition (APC). The USM images were analyzed using a custom-made MatLab script, to determine the thickness of the TrA. Results A two-way repeated-measurements ANOVA was performed with a significant effect of the factor condition [F(2,38) = 47.82, p

The paper considers an analysis of the juggling dataset based on registration. An elementary landmark registration is used to extract the juggling cycles from the data. The resulting cycles are then registered to functional principal components. After the registration step the paper then lays its focus on a functional principal component analysis to explain the amplitude variation of the cycles. More results about the behavior of the juggler’s movements of the hand during the juggling trials are obtained by a further investigation of the principal scores.

Traditionally, product development for reticle defect inspection mostly addressed operational requirements of the mask shops with highly individualized manufacturing. As a result, limited automation capability was available as compared to the standards in wafer production. Wafer fabs are guided by completely different conditions. Thousands of active reticles exist in a single fab requiring frequent re-inspections without interruption of wafer exposures. This requires high throughput of inspection tools, smart management of tool fleet, sophisticated scheduling and in-time execution of reticle inspections linked to the wafer manufacturing. The paper reports about the successful implementation of fully automated reticle defect inspection in a high-volume advanced logic fab. Automation scenarios - created based on existing SEMI standards - included inspection scheduling, reticle transport and inspection tool operation. A considerable productivity gain for the operation of Lasertec MATRICS X700 series inspection tools was obtained. Based on the learning throughout implementation, the requirements to the automation capability and tool operation as well as adjustments to working procedures are discussed.

In recent years, randomization of process order as well as randomization of the wafer map in the cassettes delivering the wafers was increasingly used to be able to correlate yield variations with specific segments of the process flow (see [1] and [2]), as well as to reduce yield influences on specific wafer positions such as top and bottom of the wafer cassette. Many randomization efforts relied on wafer sorter based randomization, which costs cycle time and wafer sorter capacity. In this paper, we describe how randomization of both process sequence as well as wafer map changes can be implemented on process equipment as part of normal processing. This kind of randomization does not add cycle time and does not require wafer sorters and will therefore be called lean randomization. We will also describe some of the most important exceptions that can occur when implementing lean randomization and we will discuss how a fab can deal with those exceptions.

Biological systems like humans or animals have remarkable stability properties allowing them to perform fast motions which are unparalleled by corresponding robot configurations. The stability of a system can be improved if all characteristic parameters, like masses, geometric properties, springs, dampers etc. as well as torques and forces driving the motion are carefully adjusted and selected exploiting the inherent dynamic properties of the mechanical system. Biological systems exhibit another possible source of self-stability which are the intrinsic mechanical properties in the muscles leading to the generation of muscle forces. These effects can be included in a mathematical model of the full system taking into account the dependencies of the muscle force on muscle length, contraction speed and activation level. As an example for a biological motion powered by muscles, we present periodic single-arm self-stabilizing juggling motions involving three muscles that have been produced by numerical optimization. The stability of a periodic motion can be measured in terms of the spectral radius of the monodromy matrix. We optimize this stability criterion using special purpose optimization methods and leaving all model parameters, control variables, trajectory start values and cycle time free to be determined by the optimization. As a result we found a self-stable solution of the juggling problem.

Mechanical properties of complex biological systems are non-linear, e.g. the force-velocity-length relation of muscles, activation dynamics, and the geometric arrangement of antagonistic pair of muscles. The control of such systems is a highly demanding task. Therefore, the question arises whether these mechanical properties of a muscle-skeletal system itself are able to support or guarantee for the stability of a desired movement, indicating self-stability. Self-stability of single joint biological systems were studied based on eigenvalues of the equation of motions and the basins of attraction were analysed using Lyapunov functions. In general, we found self-stability in single muscle contractions (e.g. frog, rat, cui), in human arm and leg movements, the human spine and even in the co-ordination of complex movements such as tennis or basketball. It seems that self-stability may be a general design criterion not only for the mechanical properties of biological systems but also for motor control.

Bourdiol developed an insole concept with so called Neuromuscular Operating Elements (NME). By influencing the plantar foot sensibility with NME, reflexes should activate so called muscle chain reactions and as a result of that, malposition of the whole locomotors system should be treated. New footorthoses(FO)-concepts use the NME. But they are controversially discussed, cause of the missing scientific background. In contrast to these FO, classical ones like Custom Moulded FO (CMFO) focus on lower limb problems [Collins et al]. Their effects are quiet validated [Murley et al]. So the aim of this study was to test the influences of CMFO with NME (Figure 1; total left) on muscle activation and plantar pressure distribution.