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Results 451 - 500 of 681
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Dolan P - - 1995
STUDY DESIGN: The authors investigated fatigue-induced changes in the frequency content of the surface electromyographic (EMG) signal from the erector spinae muscles. OBJECTIVES: The objective of the study was to understand the EMG changes in fatiguing muscle and to obtain a reliable index of fatigue. SUMMARY OF BACKGROUND DATA: Power ...
Degani S - - 1995
Thirty-two consecutive patients, referred for prenatal diagnosis by chorionic villous sampling, were examined by transvaginal ultrasound for the presence of myometrial contractions before and after the procedure. Increased myometrial activity was observed in 78% of patients. The mean frequency increased by 3.5 times and the amplitude increased by 4.2 times ...
Bilodeau M - - 1995
The purpose of the present study was to determine the specific changes occurring in the power spectrum with an increasing force level during isometric contractions. Surface electromyographic signals of the triceps brachii (TB) and the anconeus (AN) of 29 normal subjects were recorded during isometric ramp contractions performed from 0 ...
Kaplan J M - - 1995
In ingestive taste reactivity analysis, the rhythmic oral motor responses observed during intraoral infusion of fluids normally ingested by rats are categorized and counted. These rhythmic movements can be likened to spout-licking in several respects. Both are emitted in the same frequency range (5-8 Hz), organized in a burst/pause pattern, ...
Dobkin B H - - 1995
Treadmill training with partial body weight support (BWS) is being advocated as a strategy to enhance walking in patients with spinal cord injury (SCI). Clinical reports have not examined the range of sensory inputs that might modulate electromyographic (EMG) output in the legs during training. During passive, manually assisted stepping ...
Zehr E P - - 1994
Movements that are performed with maximal velocity and acceleration can be considered ballistic actions. Ballistic actions are characterized by high firing rates, brief contraction times, and high rates of force development. A characteristic triphasic agonist/antagonist/agonist electromyographic (EMG) burst pattern occurs during ballistic movement, wherein the amount and intensity of antagonist ...
Levin M F - - 1994
The correlation between the severity of spasticity and residual muscular activity is unclear, yet the latter is often used to investigate the effects of therapeutic interventions in spastic movement disorders. Our objectives were to compare the EMG and force generated by the ankle plantar- and dorsi-flexors in normal and spastic ...
Herzog W - - 1994
The purpose of this study was to investigate the behavior of electromyographical (EMG) and vibromyographical (VMG) signals in the time and frequency domains during a fatigue protocol. EMG and VMG records were obtained from the rectus femoris (RF) and vastus lateralis (VL) muscles of 11 adult male subjects during sustained, ...
Westerga J - - 1994
The EMG of the soleus muscle was recorded with bipolar electrodes chronically implanted in rats aged 10-30 days. Changes in the activity pattern were studied in relation to motor development. The firing pattern and shape of motor units were studied at higher resolution. EMG activity was closely related to motor ...
Arena J G - - 1994
A number of investigators in recent years have called for the development of devices that can monitor surface EMG levels in individuals' normal environments for use with patients who suffer from disorders in which the etiology or maintenance of the pathology is presumed to be due at least in part ...
Clarys J P - - 1994
The purpose of this study was to provide electromyographic feedback for (1) pedagogical advice in motor learning, (2) the ergonomics of materials choice and (3) competition. For these purposes: (1) EMG data were collected for the Stem Christie, the Stem Turn and the Parallel Christie (three basic ski initiation drills) ...
Schumann N P - - 1994
In 20 healthy subjects, 16-channel surface electromyograms (EMG) were recorded with the mandible in its postural position, during compensation for forces applied from ipsilateral, contralateral and frontal positions, and during force-constant biting on a unilaterally placed force transducer. After artefact elimination, EMG power spectra were calculated on the basis of ...
Sadhukhan A K - - 1994
During digitization of surface EMG, the signal is converted by an Analog-to-Digital (A/D) convertor at a specific sampling rate. This sampling rate should be selected cautiously because a high rate may include noise signals and a low rate may lead to errors. The present study was undertaken to show the ...
Buneo C A - - 1994
1. The timing and intensity of phasic muscle activation were related to the distance of reaching movements of the human arm. We dissociated phasic components of muscle activation from complete muscle activation waveforms by subtracting waveforms obtained during very slow movements. 2. We recorded electromyographic (EMG) activity from elbow and/or ...
Bilodeau M - - 1994
In order to be considered a potential tool for the characterization of muscle activity, the reliability of EMG power spectral analysis should be demonstrated. In this study, the reliability of the mean power frequency (MPF) and of the median frequency (MF) of power spectra (triceps brachii (TB), anconeus (AN)) obtained ...
Latwesen A - - 1994
This investigation explored pattern recognition of EMG signals produced by shoulder area muscles to identify the performance of a select number of lower arm motions. The signals were modelled as fourth-order autoregressive processes with the parameters of the models used to classify the different motions. The recorded EMG signal was ...
Bercik P - - 1994
BACKGROUND/AIMS: Assessment of the neuromuscular control of small intestinal motility and movement of luminal contents is hampered in vivo by measurement techniques and in vitro by tissue viability. The aim of this study was to establish the structural and functional integrity of an isolated segment of rat ileum and characterize ...
Dietz V - - 1994
Records were made of electromyographic (EMG) responses of both upper limb muscles and the corresponding elbow joint movements following sinusoidal (0.3 Hz) isometric displacement of the elbow joint itself. Two motor conditions were tested. Firstly, the subjects had to control elbow position and secondly control joint torque. Randomly timed, flexing ...
Flanders M - - 1994
1. Temporal patterns of electromyographic (EMG) activity were related to the direction of fast reaching movements. Reaches were to 20 targets in the sagittal plane of the human arm. 2. The subtraction of EMG levels recorded during very slow movements to each target allowed this study to focus on the ...
Queisser F - - 1994
A group of 12 healthy men volunteered for the experiment. Electromyograms (EMG) were obtained from semispinalis capitis, splenius capitis, levator scapulae, and trapezius muscles. The flexion angle of the cervical spine was precisely adjusted to 0 degrees, 10 degrees, 20 degrees, and 30 degrees relative to the horizontal, with a ...
Latash M L ML Department of Physical Medicine and Rehabilitation, Rush Medical College, Chicago, IL - - 1994
Predictions of three models of single-joint motor control were compared with experimental observations of the changes in electromyographic (EMG) patterns during fast voluntary movements against an unexpectedly reduced inertial load. The subjects performed elbow flexions over 40 degrees "as fast as possible" in two series. During the first series, an ...
Tschoepe B A - - 1994
While much is known about the physiological basis of local muscular fatigue, little is known about the kinematic and electromyographic (EMG) consequences of brief fatiguing isometric contractions. Five male subjects performed a horizontal elbow flexion-extension reversal movement over 90° in 250 ms to reversal before and after one of five ...
Nielsen J - - 1994
The aim of the present study was to investigate the power spectrum of the rectified electromyographic (EMG) activity during gait in order to achieve an optimal cut-off frequency before calculating the EMG envelope. The frequency content of the rectified EMG signals was found to differ substantially between healthy subjects and ...
Constable R - - 1994
Surface electromyographic (SEMG) signals are often used to study motor control during human movement. Typically, the SEMG signal is used to determine when the muscle was on or off during the movement. However, determining the time-based frequency content of the SEMG signal in conjunction with the time-history of the movement ...
Moritani T - - 1994
The purpose of this study was to investigate the possible neurophysiological mechanism of EMG signal silence (premovement silence (PMS)) preceding a ballistic movement in 10 healthy volunteers. The subjects were asked to respond to a flashing light signal by performing a plantar flexion in the ankle as strongly and quickly ...
Yuanhui M - - 1993
In an analysis of the influence of the preparatory process on motor output by measuring the EMG latencies of synergic muscles for elbow flexion and forearm supination the optimum foreperiod was between 2.0 and 2.2 sec., and a specific effect on movement pattern was not observed. However, reduction in EMG-RTs ...
Dunbar D C - - 1993
1. The electromyographic (EMG) activity of the four neuromuscular compartments in lateral gastrocnemius (LG) of cats was investigated to determine whether these intramuscular subdivisions could be activated differentially during automatic postural corrections. EMG electrodes were surgically implanted into each of the four compartments of left LG-LG1, LG2, LG3, and LGm--in ...
Park E - - 1993
During a sustained muscle contraction, the amplitude of electromyographic (EMG) signals increases and the spectrum of the EMG signal shifts toward lower frequencies. These effects are due to muscular fatigue and can cause problems in the control of myoelectric prostheses and in the estimation of contraction level from the EMG ...
Ives J C - - 1993
Maximally fast, self-terminated elbow flexion movements were performed by 10 male and 10 female college-aged subjects to assess potential gender-related differences in kinematics and the triphasic electromyographic (EMG) pattern. The subjects were instructed to move their forearms as fast as possible through 90 degrees of elbow flexion range of motion ...
Lyons M F - - 1993
Local muscle fatigue was investigated in the anterior temporal and masseter muscles during sustained isometric contractions. The volunteers' subjective perception of fatigue or pain was recorded at intervals during the sustained contractions, and this level was then compared to objective measures of fatigue. These objective measures included shift in median ...
Niebuhr B R - - 1993
The purpose of the present research was to investigate the use of surface EMG in assessing effort while measuring grip strength with the Jamar dynamometer. We hypothesized that sincere, maximal grip contractions could be distinguished from feigned, submaximal contractions by differences in the amplitude and frequency content of the EMG, ...
He C - - 1993
Applying the newly developed multistage evaluation method based on the fuzzy sets theory, we have evaluated the sense of driving fatigue of 8 male drivers who covered 400 km in 8 hr in the daytime, empirically revealing the distribution of the degree of driving fatigue. The critical values from "no" ...
Valdez D T - - 1993
This study in three dogs explores the effect of magnetically induced electrical stimulation of the brain to induce swallowing and produce contraction of the upper esophageal sphincter (UES). Single stimuli were delivered at intervals from 15 s to 3 min. Studies were performed with and without perfusion of fluid into ...
Le Pellec A - - 1993
Tonic neck reflexes (TNR) are often assumed to be included in the building of voluntary motor programmes. The present study was designed to test the importance of TNR in the performance by healthy human adults of high level dynamic exercise. The subjects were placed in an experimental situation similar to ...
Yamazaki Y - - 1993
Normal human subjects made rapid extensions of the elbow from an initial position to visual targets at different angular distances (9 degrees-54 degrees). We recorded joint angle, acceleration, and surface electromyograms (EMGs) with a monopolar electrode from the triceps and the biceps brachii muscles. Both the agonist triceps and antagonist ...
Koh T J - - 1993
The purposes of this study were to quantify the effectiveness of various methods to minimize cross talk in surface electromyography (EMG) using common recording equipment, and to compare the intra- and interday variabilities of signals recorded with these methods. Comparisons were made for signals recorded with the single differential (SD), ...
Constable R - - 1993
The frequency content of the surface electromyographic (SEMG) signal is used to study neural activity, and force development and fatigue in muscle. The fast Fourier transform (FFT), or short time Fourier transform (STFT), are commonly used to determine the frequency content of the SEMG, but have the drawback of assumed ...
Fuglevand A J - - 1993
1. The purpose of the study was to examine the dependence of neuromuscular propagation impairment on the level of isometric force sustained to the endurance limit. The task involved human volunteers sustaining a submaximal abduction force with the index finger by activating the first dorsal interosseous muscle as long as ...
Kirsch R F RF Department of Biomedical Engineering, McGill University, Montreal, Quebec, - - 1993
We have examined the time variations of stretch reflex dynamics throughout rapid voluntary changes in the isometric contraction level of the human triceps surae muscles. This was achieved by superimposing a small stochastic displacement upon many such changing contractions and then identifying the time-varying relationship between the perturbation and the ...
Yamazaki Y - - 1993
When normal subjects made rapid isometric extensions of the elbow to target torque, the agonist electromyograms (EMGs), recorded by a monopolar surface electrode, initiated from an EMG volley which was characterized by a negative potential immediately followed by a positive one. This study examined properties of the EMG volley and ...
Lucidi C A - - 1992
Subjects made fast, accurate, consistent wrist flexions under normal conditions and under conditions of low-frequency fatigue. Movements made 1 h after fatiguing exercise were indistinguishable from those made before exercise, even though twitch tensions were only approximately 60% of their fresh values. Electromyograms (EMGs) recorded from the fatigued muscles were, ...
Denny M - - 1992
EMGs were recorded from muscles of the lip, jaw, and neck during conversational speech of 17 stuttering subjects. Averaged power spectra and coherence between pairs of EMGs were computed. Results indicate that tremorlike oscillations in the range of 5-15 Hz and high amplitudes of EMGs occupy a common continuum of ...
Howell P G - - 1992
A computer-based system is described which records and analyses electromyographic (EMG) signals and tracking data for mandibular movements during function. EMG signals were obtained bilaterally from six muscles and a Sirognathograph monitored the position of the lower incisor teeth in three dimensions. Directed jaw movement tasks by subjects were monitored. ...
Loudon G H - - 1992
This paper relates to the use of knowledge-based signal processing techniques in the decomposition of EMG signals. The aim of the research is to automatically decompose EMG signals recorded at force levels up to 20 per cent maximum voluntary contraction (MVC) into their constituent motor unit action potentials (MUAPS), and ...
Hägg G M - - 1992
Alterations of the electromyographic power spectrum have been studied extensively to assess fatigue development in the neuromuscular system. Usually, a data reduction has been applied to create an index based on the mean power frequency or the median frequency. The physiological origin of the spectrum alterations has been (and to ...
Poumarat G - - 1992
Previous studies have considered the effects of the superimposition of electrical stimulation (ES) upon maximal voluntary contraction (MVC) under isometric conditions. This investigation considered these effects using isokinetic muscle action. Eleven males, non athletes, volunteered for the experiment. Isokinetic torque for extension of the right knee was measured by means ...
Sherwood D E - - 1992
To investigate whether spatial assimilation effects are due to premovement control processes or postinitiation feedback processes, surface EMG recordings were made from two agonists and one antagonist during both single and dual movements involving the upper limb(s). In the single condition, subjects (N = 7) made 25 Short (20 degrees) ...
Throckmorton G S - - 1992
A commercial computer recording system (BioPak) was tested for its accuracy and reproducibility in recording mandibular motion and muscle activity levels (EMG). Accuracy of measurements of mandibular motion was tested using sliding calipers. Accuracy of muscle activity levels was checked with a sine-wave calibration signal of known amplitude and frequency. ...
Normand M M - - 1992
We averaged sensory nerve action potentials (SNAP) of the median nerve recorded at the wrist, forearm, and elbow with up to 6,000 trials in the presence of quantitated levels of background EMG activity in six normal volunteers. The SNAP could be recorded reproducibly with averaging when the EMG amplitude was ...
Poliakov A V - - 1992
The relationship between the averaged surface electromyogram (EMG) and the activity of motoneurones in reflex studies is analysed mathematically. This analysis reveals that, subject to certain conditions being met, the integral of the average of the unrectified EMG is linearly related to the activity of motor units in the muscle. ...
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