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Results 601 - 650 of 778
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Brand R A - - 1994
Connective tissues have the capacity to adapt to a changing mechanical environment. Considerable experimental evidence suggests, however, that tissues respond to only a small portion of mechanical loads they experience and thus ignore the majority of the load they experience. Evidence suggests that tissues 'temporally process' these external mechanical signals ...
Bader D L - - 1994
An apparatus and test method were developed to determine the elastic stiffness and damping coefficient of human cartilage in compression. An underdamped, counterbalanced beam applied a sudden compressive force to a full-thickness cylindrical specimen of articular cartilage. The initial oscillatory response decayed to steady state creep after approximately 10 cycles ...
Hua J - - 1994
Symmetrical, asymmetrical, and custom asymmetrical stems without collars were manufactured and inserted without cement, in that order, into each of eight femora. Displacement transducers were mounted at different locations to measure relative motion between the stem and the bone. A load was applied to simulate the forces acting on a ...
Gottlieb G L GL Department of Neurological Sciences, Rush Medical College, Chicago, IL - - 1994
We describe the effects of changing an elastic or inertial load on the trajectory and EMG patterns during fast, voluntary elbow flexions. These effects depend upon whether the load is known to the subject in advance of the movement or is only determined as the movement is performed. The EMG ...
Wan Abas W A - - 1994
Local strains acting across an area of skin loaded uniaxially in vivo are converted to stresses using the standard elastic formulae. The stress values are compared to those obtained using the classical Bossinesq and Michell stress functions. The results indicate that these functions are capable of describing the response of ...
Wilke H J - - 1994
We report a new apparatus to determine the quasistatic, three-dimensional, load-displacement characteristics of spines including muscle forces. The loading frame can be adapted to mono- and polysegmental specimens from the lumbar or cervical spine as well as to entire spines. Three force and three moment components can be applied in ...
Butler D - - 1993
The purpose of this study was to analyse the influence of load knowledge on lifting technique. Ten men lifted a box containing either no weight or weights of 150, 250 or 300 N with and without knowledge of what was inside the box. The kinetics and kinematics of the lift ...
Zhu W - - 1993
The objectives of this study were to determine the viscoelastic shear properties of articular cartilage and to investigate the effects of the alteration of proteoglycan structure on these shear properties. Glycosidase treatments (chondroitinase ABC and Streptomyces hyaluronidase) were used to alter the proteoglycan structure and content of the tissue. The ...
Osvalder A L - - 1993
A method was developed to study the biomechanical response of the lumbar motion segment (Functional Spinal Unit, FSU) under a dynamic (transient) load in flexion. In order to inflict flexion-distraction types of injuries (lap seat-belt injuries) different load pulses were transferred to the specimen by means of a padded pendulum. ...
McRobbie D W - - 1993
A theoretical derivation of the equivalent loading resistance of an annular volume conductor within a magnetic resonance imaging radio frequency (RF) coil is presented. Theoretical predictions of the magnitude of the load resistance agree well with measurement over a range of frequencies. The loading resistance is proportional to the sample ...
Lee M - - 1993
OBJECTIVE: The purpose of this investigation was to study the spinal deformations produced by applying a force to a lumbar vertebra and to compare the deformation responses at three different loading rates. SETTING: The study was conducted in a laboratory setting using a mechanical device to simulate the manipulative procedure ...
Mishchenko V S - - 1993
The results of a series of experiments carried out under heavy physical loads during the training of 96 elite cyclists, rowers and swimmers were based on the following: (1) complex analysis of dynamics of sensitivity, stability and speed of responses of cardio-respiratory system (CRS) to hypoxia, CO2-H+ ionic irritants; (2) ...
Bock O - - 1993
We investigated the kinematics of pointing movements in human subjects while varying the weight load carried by their hand. In accordance with our previous study, we found that movement velocity decreased and duration increased with load size, while skewness of velocity profiles and final pointing position were load-independent. When the ...
Schendel M J - - 1993
Facet forces, longitudinal ligament loads, and vertebral body motion were experimentally measured in five fresh human lumbar spine segments, L1-L2. Strain gages on the bone surface were used to quantify facet loads. Buckle transducers were used to measure anterior and posterior longitudinal ligament loads. The three-dimensional motion of the motion ...
Galbraith J A - - 1993
There is a limited amount of information available on the mechanical and functional response of the nervous system to loading. While deformation of cerebral, spinal, or peripheral nerve tissue can have particularly severe consequences, most research in this area has concentrated on either demonstrating in-vivo functional changes and disclosing the ...
Simmons R W RW Department of Physical Education, San Diego State University, CA - - 1993
Ten right-hand-dominant subjects completed a series of unsighted, goal-directed, arm flexion movements under three different mechanical loading conditions: an inertial load, an elastic spring load, and a stretched-spring load. Subjects completed a series of inertial load training trials followed by random application of one of the three loads. Three time ...
Setton L A - - 1993
A review of the structure-function relationships for normal articular cartilage is provided. This provides the foundation for understanding the roles played by collagen, proteoglycan and water in determining the material properties of the tissue. A summary of biomechanical and compositional changes in human osteoarthritic cartilage is also presented. Finally, the ...
Stiehl J B - - 1993
The range of motion of 10 fresh cadaveric ankle specimens was measured for flexion, anterior-posterior drawer, inversion-eversion, and internal-external rotation under conditions that simulated normal weight-bearing. At a 70 kg load, range of motion significantly diminished in all directions (p < 0.005). Plantar flexion was diminished to a greater degree ...
Runciman R J - - 1993
A six-channel instrumented load transducer has been developed for measuring hand and upper limb loading (maximum design load, 2 kN). Modular in design, the transducer can be adapted to a variety of formats, thereby increasing the range of activities to which it can be applied. When used with a motion ...
Awbrey B J - - 1993
This report describes the use of a new micro-thin resistive-based sensor to measure dynamic vertical loading of normal and osteoarthritic (OA) human knee cartilage repetitively under conditions of simulated knee joint loading. Articular cartilage discs were cultured in 3 DMEM +/- IL-1, lipopolysacharide (LPS) and trypsin over 7 days. Loading ...
Whalen R - - 1993
Theoretical models and experimental studies of bone remodeling have identified peak cyclic force levels (or cyclic tissue strain energy density), number of daily loading cycles, and load (strain) rate as possible contributors to the bone modeling and remodeling stimulus. To test our theoretical model and further investigate the influence of ...
Mita K - - 1993
It has been reported that accuracy in the measured point of force application depends on the position and magnitude of load. The aim of this study is to investigate the error in measuring the body center of pressure in a standing posture with a force plate and to improve the ...
Strek P - - 1993
40 thyroid cartilages were used to investigations, they were taken from bodies of people, died between the ages of 19-99, by the use of the endurance machine with controlled speed of the increase of deformation. It was observed that the durability for flexion and the inflexibility of the investigated cartilages ...
Tsukamoto Y - - 1992
It has been postulated that most hip motion occurs at the inner bearing in bipolar hip prosthesis. However, radiography and cineradiography analyses have shown that the inner bearing is not always the primary articulation. We studied the frictional behavior of bipolar prosthesis and Austin-Moore prostheses and the motion of the ...
Wilmink J - - 1992
The high incidence of partial rupture of the superficial digital flexor tendor in the equine athlete represents a major cause for concern in the racing industry. Frequently, the lesion is localised to the central core of the tendon. This study tested the hypothesis that the site specific structural failure results ...
dos Santos J J - - 1992
Protrusive functional relationships between the upper and lower jaws are constrained by the structures of the temporomandibular joints (TMJs) and the opposing contacting surfaces of the anterior teeth. To check these biomechanical relationships, the link quadrilateral bell crank model was assumed in order to compute the instantaneous equilibrium of forces ...
Whitesides T E - - 1992
Seven different halo systems were evaluated biomechanically to compare the force exerted by the halo pin in each system. In three different experiments torque values of 2, 4, 6, 7, and 8 in lb were applied to the halo pin, and the force at the skull end of the halo ...
Marras W S - - 1992
Although researchers have shown that dynamic activity may greatly increase the predicted loading experienced by a joint, most ergonomic assessments in the workplace have focused on the postures of the workers and the loads imposed on a joint due to these postures, ignoring the influence of dynamic motion on joint ...
Parkkinen J J - - 1992
Cultured bovine articular cartilage was subjected to 50 ms, 0.5-1.0 MPa compressions repeated at intervals of 2-60 s for 1.5 h and simultaneously labeled with 35SO4. The compression was delivered with a 4-mm-diameter nonporous loading head on an 8-mm-diameter cartilage explant. This method created directly compressed (central) and uncompressed (border) ...
Simmons R W - - 1992
Ten subjects completed a series of goal-directed arm flexion movements unexpectedly perturbed by three different types of mechanical load. Examination of electromyograph (EMG) waveforms and kinematic information collected during randomly distributed test trials facilitated investigation into the interaction between loading conditions and the response-associated EMG innervation patterns. Results of the ...
Jäger M - - 1992
Previous biomechanical analyses of typical load manipulation tasks were mainly limited to sagittal-plane activities or to static cases. This paper includes the biomechanical determination and assessment of lumbar load during asymmetrical bi-manual materials handling tasks which involve lateral turning of the body, trunk inclination, and sagittal flexion and lateral bending ...
Leskinen T P - - 1992
The purpose of this study was to measure dose of spinal load when different pacing methods were applied to lifting work and to develop methodology for such measurements. The compressive load on the spine computed by a dynamic biomechanical model and the electromyographic activity of back muscles were used for ...
Komi P V - - 1992
Direct in vivo Achilles tendon force measurements open up new possibilities for understanding the loading of the Achilles tendon during natural locomotion. This article describes how these human experiments can be performed. The results of these experiments imply that Achilles tendon forces are unexpectedly high in certain activities (e.g., hopping) ...
Reynolds D P - - 1992
A finite-element analysis is made for the compression of soft tissues of the residual lower limb contained in a prosthetic socket. The analysis is relevant to static loading during stance in a patellar-tendon-bearing, below-knee design of socket. Values of Young's modulus are obtained experimentally for use in the model. One ...
Richardson C - - 1992
In this and a previous experiment it has been observed that subjects produce innervation patterns (EMG) that are load specific, i.e., they produce concentration patterns for movements made with inertial loads and triphasic patterns for movements made with elastic loads. The protocol of these experiments prevented any adaptive responses to ...
Qu X - - 1992
Various mechanical forces produce a variable stimulus intensity on bone and have different effects on its growth and development. The aim of this project was to study the effects of a variety of mechanical forces on human humerus morphology. This was investigated by measuring the cortical thickness (cm) and diameter ...
Gagnon M - - 1992
Whatever the lifting method used, dynamic factors appear to have an effect on the safe realization of movement, and NIOSH guidelines recommend smooth lifting with no sudden acceleration effects. On the other hand, inertial forces may play an important role in the process of transfer of momentum to the load. ...
Gauffin H - - 1992
We studied nine patients with an isolated, unrepaired rupture of the anterior cruciate ligament to evaluate whether well-rehabilitated patients with an old rupture of the anterior cruciate ligament had adapted their patterns of motor control in situations that provoke knee instability and if the possible adaptation results in a measurable ...
Williams R B - - 1992
Although normal pressures at the stump socket interface of the lower-limb amputee have been investigated, little is known about the shear stresses that also occur. Studies suggest that the combination of both shear and normal stresses significantly exacerbates discomfort and vascular and tissue damage. A means of simultaneously measuring normal ...
de Looze M P - - 1992
Boxes were lifted and lowered repetitively at three different combinations of load and frequency. These combinations were chosen such that the total mechanical power generated was constant. Effects of the varying load or frequency conditions (but constant total mechanical power) on the rate of energy expenditure (M) and on the ...
Greco F - - 1992
Ultrastructural analysis was conducted on samples of articular cartilage taken from both load-bearing and non-load-bearing areas with the aim of evaluating the morphologic adaptation of the articular cartilage to mechanical stimulation and identifying the mechanisms of interaction of the chondrocyte and the matrix. Through this analysis we were able to ...
An K N - - 1992
Intersegmental loading pattern on the elbow joint during a push-up exercise was investigated. Electromagnetic motion sensors and a piezoelectric force plate were used to simultaneously record upper extremity motion and forces on nine healthy male subjects during push-ups in six different hand positions. Peak axial forces exerted on the elbow ...
Johansson R S RS Department of Physiology, Umeå University, - - 1992
In the previous paper regarding the somatosensory control of the human precision grip, we concluded that the elicited automatic grip force adjustments are graded by the amplitude of the imposed loads when restraining an 'active' object subjected to unpredictable pulling forces (Johansson et al. 1992a). Using the same subjects and ...
Kasra M - - 1992
To improve our understanding of the dynamic characteristics of the human lumbar spine, both experimental and finite-element methods are required. The experimental methods included measurement of the axial steady state response, resonant frequencies, and damping of seven lumbar motion segments under an upper-body mass of 40 kg. The influence of ...
Bock O - - 1992
Human subjects pointed at stationary visual targets without sight of their arm while the force environment was varied by applying weight or spring loads to the hand. The path travelled by the finger, pointing accuracy, and the shape of the finger velocity profile remained invariant across all force environments after ...
Levin M F MF Centre de Recherche en Sciences Neurologiques, Université de Montréal, Québec, - - 1992
According to the equilibrium-point hypothesis, movements are produced by means of displacement of the invariant torque/angle characteristic (IC) of the joint and change in its slope. Displacement is produced via the central reciprocal (R) command while the coactivation (C) command specifies the slope of the IC. Neurophysiologically, the R command ...
McNally D S - - 1992
A technique was developed for measuring the distribution of stress within loaded cadaveric intervertebral discs. A strain-gauged membrane mounted on the side of a 1.3-mm diameter needle was pulled through the disc at constant speed. The orientation of the membrane was changed by rotating the needle, so that profiles of ...
Larsson T - - 1991
Cultured bovine articular cartilage full thickness explants were mechanically loaded, both statically and cyclically, at high frequency (2s of load with 2s intervals of no load) and low frequency (60s of load with 60s intervals of no load), at 1 MPa. Metabolic effects of the load were studied by radiolabeling ...
Miller M A - - 1991
Twenty-five fully anesthetized swine were tested for biomechanical responses to lower abdominal steering-wheel loading. Supine subjects were impacted with the lower rim of a segmented steering wheel in a ventrodorsad direction at approximately the L-4 level of the lumbar spine. Peak force ranged from 0.13 to 8.56 kN, peak stroke ...
Kram R - - 1991
People throughout Asia use springy bamboo poles to carry the loads of everyday life. These poles are a very compliant suspension system that allows the load to move along a nearly horizontal path while the person bounces up and down with each step. Could this be an economical way to ...
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