EMG Data (emg + data)

Distribution by Scientific Domains


Selected Abstracts


Quantification of surface EMG signals to monitor the effect of a Botox treatment in six healthy ponies and two horses with stringhalt: Preliminary study

EQUINE VETERINARY JOURNAL, Issue 3 2009
I. D. Wijnberg
Summary Reasons for performing the study: Therapeutic options for stringhalt in horses are limited, whereas medical experiences with botulinum toxin type A (Botox) have been positive. To evaluate its effectiveness in horses, surface electromyography (sEMG) signals before and after injection need to be quantified. Hypothesis: Treatment of healthy ponies and cases with Botox should reduce muscle activity in injected muscles and reduce spastic movements without adverse side effects. Methods: Unilaterally, the extensor digitorum longus, extensor digitorum lateralis and lateral vastus muscles of 6 healthy mature Shetland ponies and 2 talented Dutch Warmblood dressage horses with stringhalt were injected (maximum of 400 iu per pony and 700 iu per case; 100 iu in 5 ml NaCl divided into 5 injections) with Botox under needle EMG guidance. Surface EMG data were evaluated using customised software, and in the individuals gait was analysed using Proreflex. Statistical analysis was performed using mixed models and independent sample t test (P<0.05). Results: Surface EMG signals were quantified using customised software. The area under the curve (integrated EMG) in time was used as variable. It became significantly reduced in injected muscles after injection of Botox in normal ponies (P<0.05). This effect was present from Day 1 until Day 84 after injection. In the 2 cases, after injection of 3 muscles, the integrated EMG in time became significantly reduced in all 3 muscles. Kinematic measurements confirmed reduction of frequency and amplitude of hyperflexing or hyperabducting strides of the affected hindlimbs. The duration of effect was also seen in the cases until around 12 weeks after injection. Conclusions and potential relevance: After EMG guided injections of Botox, sEMG signals recorded from injected muscle were reduced, which proves this to be a useful tool in statistically evaluating a treatment effect. The positive results of this pilot study encourage further research with a larger group of clinical cases. [source]


Electromyographic and kinematic indicators of fatigue in horses: a pilot study

EQUINE VETERINARY JOURNAL, Issue S33 2001
G. R. COLBORNE
Summary Muscle fatigue can be quantified using Fourier analysis of the recorded EMG signal. Median frequency is the frequency at which the Fourier profile is bisected, and this measure typically shifts to smaller values during fatigue. This technique was combined with kinematic analysis to describe the time course of fatigue in horses galloping on an inclined treadmill. It was hypothesised that EMG median frequency would decrease in tandem with changes in kinematic variables through the exercise test. Three fit Thoroughbred horses had retroreflective markers placed on their hooves and withers. Surface electrodes were attached to the skin over the forelimb deltoid muscle. After warm-up at walk and trot, each horse galloped at 110% VO2max on a treadmill inclined to 7.5% until fatigue onset. Kinematic data were recorded at 200 Hz for 5 s at 30s intervals, and raw EMG data were recorded at 1024 Hz for 3 s at 15 s intervals. Fatigue onset was the point in time when the horse could not keep up with the treadmill speed with minimal encouragement. One horse performed the entire exercise test on the same lead, while the other 2 horses changed leads periodically, interrupting the changes in both the EMG and kinematic measurements. Overall, through the course of the trials, mean stride length increased by 0.34 m and stride duration increased by 0.03 s. Vertical excursion of the trunk marker increased by 0.03 m. For the horse that did not change lead, median frequency of the EMG signal decreased by 36%. In the other 2 horses, lead changes were interspersed between smaller decreases in median frequency, whereupon median frequency recovered to starting levels immediately following a lead change. The median frequency decreased by 12-20% between lead changes. Kinematic changes are more global indictors of fatigue, while the EMG indicators are dependent upon lead changes. [source]


Improving functional magnetic resonance imaging motor studies through simultaneous electromyography recordings

HUMAN BRAIN MAPPING, Issue 9 2007
Bradley J. MacIntosh
Abstract Specially designed optoelectronic and data postprocessing methods are described that permit electromyography (EMG) of muscle activity simultaneous with functional MRI (fMRI). Hardware characterization and validation included simultaneous EMG and event-related fMRI in 17 healthy participants during either ankle (n = 12), index finger (n = 3), or wrist (n = 2) contractions cued by visual stimuli. Principal component analysis (PCA) and independent component analysis (ICA) were evaluated for their ability to remove residual fMRI gradient-induced signal contamination in EMG data. Contractions of ankle tibialis anterior and index finger abductor were clearly distinguishable, although observing contractions from the wrist flexors proved more challenging. To demonstrate the potential utility of simultaneous EMG and fMRI, data from the ankle experiments were analyzed using two approaches: 1) assuming contractions coincided precisely with visual cues, and 2) using EMG to time the onset and offset of muscle contraction precisely for each participant. Both methods produced complementary activation maps, although the EMG-guided approach recovered more active brain voxels and revealed activity better in the basal ganglia and cerebellum. Furthermore, numerical simulations confirmed that precise knowledge of behavioral responses, such as those provided by EMG, are much more important for event-related experimental designs compared to block designs. This simultaneous EMG and fMRI methodology has important applications where the amplitude or timing of motor output is impaired, such as after stroke. Hum Brain Mapp 2006. © 2006 Wiley-Liss, Inc. [source]


Effects of endodontic instrument handle diameter on electromyographic activity of forearm and hand muscles

INTERNATIONAL ENDODONTIC JOURNAL, Issue 2 2001
T. Ozawa
Abstract Aim To determine the influence of the handle diameter of endodontic instruments on forearm and hand muscle activity using electromyographic (EMG) recording. Methodology Size 45 K-type files were fitted with four different handle diameters; 3.5, 4.0, 5.0, and 6.0 mm. Seven dentists then attempted to negotiate to the working length acrylic resin root canals with each of the four handle sizes using a reaming motion. EMG activities were recorded from the flexor pollicis brevis muscle (f.p.b.), the flexor carpi radialis muscle (f.c.r.), and the brachioradialis muscle (b) with bipolar surface electrodes. The time taken to negotiate the canals, the area of integrated EMG that corresponded to the amount of EMG activity required during penetration and the maximum amplitude of EMG were measured using the EMG data. Results were analysed statistically using a one-way factorial anova test and multiple comparison tests. Results Reaming time and integrated EMG area of each muscle decreased with an increase in handle diameter. The most significant difference in time and area of integrated EMG was detected between handles of 6 mm and 3.5 mm diameter (time: P < 0.01, area of the f.p.b.: P < 0.01, area of the f.c.r. and b: P < 0.05), and between handles of 5 mm and 3.5 mm diameter (P < 0.05). Both 5 mm and 6 mm handles significantly decreased the maximum amplitude of EMG recorded from the f.p.b. compared with 3.5 mm handles (between 3.5 mm and 6 mm: P < 0.01, between 3.5 mm and 5 mm: P < 0.05). Conclusion The results indicate that handle diameter has an effect on reaming time as well as on muscle activity. As a consequence, handle diameter influenced operator performance during instrumentation. [source]


Effects of interocclusal appliances on EMG activity during parafunctional tooth contact

JOURNAL OF ORAL REHABILITATION, Issue 6 2003
A. L. Roark
summary, To test the hypothesis that a flat plane interocclusal appliance affects the electromyographic (EMG) activity of the temporalis and masseter muscles in pain-free individuals, maxillary splints were fabricated for 20 individuals who reported no history, signs or symptoms of myofascial pain or arthralgia as determined by two trained, independent examiners. Subjects were instructed to establish light tooth contact, maximum clenching, and moderate clenching with/without the splint in place (as determined by random assignment) while EMG data from the left and right temporalis and masseter muscles were recorded. A 5-min biofeedback training session to relax the masticatory muscles was followed by a repetition of the tooth contact/clenching tasks with/without the splint in place. With the splint in place, the activity of the temporalis muscles decreased for all tasks, significantly for the left and right temporalis under maximal clenching and for the right temporalis under moderate clenching. In contrast, the activity of the masseter muscles increased under light and moderate clenching (significantly for the left masseter under moderate clenching) and decreased slightly under maximal clenching. The effectiveness of interocclusal appliances may be due to mechanisms other than redistribution of adverse loading. [source]


Ankle eversion torque response to sudden ankle inversion Torque response in unbraced, braced, and pre-activated situations

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 2 2005
Lars Konradsen
Abstract In 13 young ankle stable subjects, ankle eversion torque and peroneal EMG were simultaneously recorded in response to sudden ankle inversion. The eversion torque response was bi-phasic. The initial development of torque, which was responsible for 30% of the maximal eversion torque response, was observed 135ms after the start of platform rotation and correlated well with the onset of the automatic postural peroneal EMG response. The remaining eversion torque response commenced after 305 ms, strongly correlating with the onset of the peroneal long latency voluntary EMG activity. With the ankle unbraced, 66% of the maximal torque level was reached in 326ms. While braced, the same torque magnitude was reached using 230ms (p < 0.02), and pre-activation of the peroneal muscles allowed the subjects to reach the same level of torque in 89ms (p < 0.0005). Prior to the study, a common reaction pattern to sudden inversion was expected in an ankle stable population, but review of the eversion torque and EMG data from the 13 subjects revealed three different voluntary reaction patterns: 10 subjects showed an efficient activation of evertor muscles; two subjects stiffened their ankles with activation of both in- and evertor muscles; and one subject showed a marginal voluntary activation of the ankle evertors. The results of the study indicate that the reaction to sudden ankle inversion is not solely automatic. The main part of the torque response is voluntarily mediated and inter-individual differences in strategy seem to exist in healthy subjects. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source]


Spontaneously changing muscular activation pattern in patients with cervical dystonia

MOVEMENT DISORDERS, Issue 6 2001
A. Münchau MD
Abstract The objective of this study was to determine stability of the neck muscle activation pattern in a given dystonic head position in patients with cervical dystonia (CD). We assessed 26 patients with CD and botulinum toxin (BT) treatment failure before surgical denervation. None of them had received BT injections for at least 4 months. To relate dystonic head position to underlying neck muscle activity, we used synchronised video and poly-electromyographic (EMG) recording over a period of 10 minutes. The muscle activation pattern during constant ("stable") maximal dystonic excursions was analysed. EMG data of nine patients was excluded from the analysis, as these patients had a constantly changing head position or marked head tremor. In the remaining 17 patients, who had a fairly stable dystonic position, muscular activation patterns during the recording spontaneously changed in nine (Group A) while in eight it remained stable (Group B). There was no significant difference in demographic variables between the two groups other than a male predominance in Group A. However, the retrospectively determined initial response to BT treatment (before BT treatment failure had occurred) was significantly worse in Group A as compared with Group B. Neck muscle activation patterns can spontaneously change in CD patients despite constant dystonic head position, implying an inherent variability of the underlying central motor program in some patients. This should be considered when BT treatment response is unsatisfactory, and should also be taken into account when interpreting results of EMG recordings of neck muscles in these patients. © 2001 Movement Disorder Society. [source]


Functional analysis of the gibbon foot during terrestrial bipedal walking: Plantar pressure distributions and three-dimensional ground reaction forces

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2005
Evie Vereecke
Abstract This paper gives a detailed analysis of bipedal walking in the white-handed gibbon, based on collected pressure and force data. These data were obtained from four gibbons in the Wild Animal Park, Planckendael, Belgium, by using a walkway with integrated force plate and pressure mat. This is the first study that collects and describes dynamic plantar pressure data of bipedally walking gibbons, and combines these with force plate data. The combination of these data with previously described roll-off patterns of gibbons, based on general observations, video images, force plates, and EMG data, gives us a detailed description of foot function during gibbon bipedalism. In addition, we compare the observed characteristics of hylobatid bipedalism with the main characteristics of bonobo and human bipedalism. We found that gibbons are midfoot/heel plantigrade, and lack the typical heel-strike of other hominoids. The hallux is widely abducted and touches down at the onset of the stance phase, which results in an L-shaped course of the center of pressure. The vertical force curve is trapezoid to triangular in shape, with high peak values compared to humans. The braking component is shorter than the accelerating component, and shortens further at higher walking velocities. Speed has a significant influence on the forefoot peak pressures and on most of the defined gait parameters (e.g., vertical force peak), and it alters the foot contact pattern as well. The investigation of existing form-function relationships in nonhuman primates is essential for the interpretation of fossil remains, and might help us understand the evolution of habitual bipedal walking in hominids. Am J Phys Anthropol, 2005. © 2005 Wiley-Liss, Inc. [source]


Movement of the tongue during normal breathing in awake healthy humans

THE JOURNAL OF PHYSIOLOGY, Issue 17 2008
S. Cheng
Electromyographic (EMG) activity of the airway muscles suggest that genioglossus is the primary upper airway dilator muscle. However, EMG data do not necessarily translate into tissue motion and most imaging modalities are limited to assessment of the surfaces of the upper airway. In this study, we hypothesized that genioglossus moves rhythmically during the respiratory cycle and that the motion within is inhomogeneous. A ,tagged' magnetic resonance imaging technique was used to characterize respiratory-related tissue motions around the human upper airway in quiet breathing. Motion of airway tissues at different segments of the eupnoeic respiratory cycle was imaged in six adult subjects by triggering the scanner at the end of inspiration. Displacements of the ,tags' were analysed using the harmonic phase method (HARP). Respiratory timing was monitored by a band around the upper abdomen. The genioglossus moved during the respiratory cycle. During expiration, the genioglossus moved posteriorly and during inspiration, it moved anteriorly. The degree of motion varied between subjects. The maximal anteroposterior movement of a point tracked on the genioglossus was 1.02 ± 0.54 mm (mean ±s.d.). The genioglossus moved over the geniohyoid muscle, with minimal movement in other muscles surrounding the airway at the level of the soft palate. Local deformation of the tongue was analysed using two-dimensional strain maps. Across the respiratory cycle, positive strains within genioglossus reached peaks of 17.5 ± 9.3% and negative strains reached peaks of ,16.3 ± 9.3% relative to end inspiration. The patterns of strains were consistent with elongation and compression within a constant volume structure. Hence, these data suggest that even during respiration, the tongue behaves as a muscular hydrostat. [source]


Early oral behaviour in preterm infants during breastfeeding: an electromyographic study

ACTA PAEDIATRICA, Issue 6 2001
K Hedberg Nyqvist
The objectives were to increase the understanding of the characteristics of oral behaviour during breastfeeding in preterm infants and to validate direct observations of infant sucking. Twenty-six infants were investigated once by simultaneous observation and surface electromyography (EMG) at 32.1,37.1 postmenstrual weeks. The orbicularis oris muscle was used for data analysis, as it provided the most distinct registrations. High correlation coefficients were observed with respect to classifications of EMG data by two raters on the number of sucks per burst (r= 0.97) and duration of sucking bursts (r= 0.99). The agreement between direct observations of sucking and EMG data was high. The median for mean number of sucks per burst was 8 (range 2,33) and for longest burst 28 (5,96) sucks. Sucks with low and very high intensity constituted a median of 14 (1,94)% and 25 (0,87)% of all sucks. The range in mean sucking frequency was 1.0,1.8 sucks s- 1. Suck duration ranged from 0.6 to 1.1 s. There was a considerable variation between infants in the extent of mouthing. No association with maturational level appeared for any of the components in oral behaviour. Conclusion: EMG data provided evidence of early sucking competence in preterm infants during breastfeeding, with wide individual variations. Surface EMG and direct observation are recommended as valid methods in the evaluation of breastfeeding behaviour in preterm infants. [source]