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At least 1,369 records · Page 76Linked to original sources
PubMed2006

Surface electromyography as a tool to assess the responses of car passengers to lateral accelerations. Part II: Objective comparison of vehicles.

The purpose of this study was to objectively assess the response of car passengers to lateral accelerations. Surface EMG signals were collected bilaterally from the cervical erector spinae (CES), latissimus dorsi (LD), erector spinae (ES), external oblique (EO), and vastus lateralis (VL) muscles of 10 subjects. Lateral acceleration was also recorded. Three chassis-seat configurations AA, BA and BB were tested, with the first letter denoting the chassis and the second the seat. SEMG signals were often contaminated by noise, and were, therefore, denoised using the methods explained in part I. Reciprocal phasic activity was observed for all muscles except for the EO, and the reaction of passengers to lateral accelerations was interpreted as a bust torsion. The RMS of EMG segments was used as an indication of muscle activity. Muscle activation of VL and ES were significantly affected by the configuration tested (p<0.05), with greater activation levels observed for the chassis A than for the chassis B. Such a finding implies that greater roll requires greater muscle activity, thus resulting in less comfortable vehicles. Therefore, SEMG can be used to provide an objective measure of discomfort in passengers subjected to lateral accelerations in a car seat.

Acceleration↗
PubMed2006

Repeatability of electromyography and force measurements of the neck muscles in adolescents with and without headache.

BACKGROUND: Reliable measurements are needed to study the dysfunction of the neck muscles. The aim of this study was to determine the intra-tester repeatability of EMG and isometric force measurements of the neck muscles in adolescents with headache and headache-free controls. METHODS: A group of 30 adolescents with migraine-type headache, 29 with tension-type headache, and 30 headache-free controls were recruited. Maximal isometric neck muscle force with simultaneous recording of surface EMG from the cervical erector spinae and the sternocleidomastoideus muscles was measured twice during one day. FINDINGS: For all groups, intra-class correlation coefficients (ICC) and coefficients of variation (CV) showed acceptable repeatability of all measurements. (Force measurements: ICC 0.98-0.99, CV 0.7-3.7%; EMG measurements: ICC 0.95-0.99, CV 4.9-10.1%.) On the individual level, variation between the consecutive measurements was found to be low in all groups. INTERPRETATION: The present EMG and force measurements of neck muscles indicate acceptable intra-tester repeatability in adolescents. The repeatability was comparable in migraine- and tension-type headache and headache-free groups. The EMG and the force measurements offer the possibility to investigate neck muscle dysfunction in adolescent headache.

Adolescent↗
PubMed2006

Similar response of agonist and antagonist muscles after eccentric exercise revealed by electromyography and mechanomyography.

The purpose of this study was to investigate the influence of eccentric contractions (ECC) on the biceps (BB) and triceps brachii (TB) muscles during maximal voluntary contraction (MVC) of elbow flexors using electrical (EMG) and mechanomyographical activities (MMG). Each of 18 male students performed 25 submaximal contractions (50% MVC) of the elbow flexors. Root mean square amplitude (RMS) and median frequency (MDF) were calculated for the EMG and MMG signals recorded during MVC. All measurements were taken before, immediately after, 24, 48, 72, and 120 h post-ECC from the BB and TB muscles. MVC was reduced by 34% immediately after exercise and did not return to the resting value within 120 h (P0.05). The EMG MDF decreased significantly (P< or =0.05) in both muscles after ECC. The MMG RMS at 24h, 48, 72 and 120 h post-ECC was significantly lower compared to that recorded immediately after ECC in both muscles (P< or =0.05). The present research showed that (i) there were similar changes in electrical and mechanical activities during MVC after submaximal ECC in agonist and antagonist muscles suggesting a common drive controlling the agonist and antagonist motoneuron pool, (ii) the ECC induced different changes in EMG than in MMG immediately after ECC and during 120 h of recovery that suggested an increased tremor and contractile impairments, i.e., reduced rate of calcium release from the sarcoplasmic reticulum (acute effect), and changes in motor control mechanisms of agonist and antagonist muscles, and increased muscle stiffness (chronic effect).

Adaptation, Physiological↗
PubMed2006

Electromyography of pelvic floor muscles.

Pelvic floor muscles (PFM) are intimately involved in function of lower urinary tract, the anorectum and sexual functions, therefore their neural control transcends the primarily important somatic innervation of striated muscle, as they are directly involved in "visceral activity". Neural control of pelvic organs is affected by a unique co-ordination of somatic and autonomic motor nervous systems. Visceral and somatic sensory fibres supply sensory information from pelvic organs; their input influences through central integrative mechanisms also pelvic floor muscle activity. Anatomically, somatic afferent and efferent nerves of the sacral cord segments, reflexly integrated at the spinal cord and brainstem level, conduct neural control of PFM. The inputs from several higher centres influence the complex reflex control and are decisive for voluntary control, and for socially adapted behaviour related to excretory functions.

Autonomic Nervous System↗
PubMed1998

The timing of congenital brachial plexus injury: a study of electromyography findings in the newborn piglet.

OBJECTIVE: Permanent congenital brachial plexus palsy is a recognized serious complication associated with shoulder dystocia. The timing and etiology of this injury remains controversial. Previous authorities have used adult-derived, non-brachial plexus data to extrapolate the anticipated timing for electromyographic denervation changes to date such injuries in the newborn. With use of a domestic swine model, this investigation tests the hypothesis that electromyographic evidence of brachial plexus denervation in the newborn is temporally different than that in the adult. STUDY DESIGN: Five healthy 2-day-old and two adult pigs underwent unilateral sharp transection of the brachial plexus. Daily electromyographic studies were performed in brachial plexus innervated muscle groups on the involved and contralateral (control) front limbs. Postmortem measurements of the transected nerve segments were obtained in one piglet and one adult animal. Representative hard copy recordings of individual electromyographic studies were collected. RESULTS: Immediately after surgical transection of the brachial plexus, no electromyographic evidence of denervation was observed. Uniformly in the newborn piglets, at 24 hours after transection, denervation in the form of fibrillation potentials, positive sharp waves, and complex repetitive discharges was seen. Serial testing demonstrated proximal to distal gradients of denervation over the next 24 to 48 hours. A delay in electromyographic evidence of denervation was observed in the two adult pigs until days 5 and 8, respectively. Control limb studies remained normal throughout the study period. Nerve length measurements for individual muscle groups were as follows for the adult and newborn pigs, respectively: deltoid 11.4 cm, 2.5 cm; cleidobrachialis 16.0 cm, 4.0 cm; triceps 15.5 cm, 4.5 cm; forelimb flexors 26.0 cm, 6.5 cm; and extensor carpi radialis 31.0 cm, 9.0 cm. CONCLUSION: Electromyographic evidence of brachial plexus denervation after surgical transection differs between the newborn and the adult pig. Consistent with wallerian degeneration, a correlation exists between length of the distal nerve segment and timing for electromyographic signs of denervation. These findings suggest it would be inappropriate to extrapolate the anticipated timing for electromyographic changes in the newborn on the basis of previously established adult non-brachial plexus data.

Aging↗
PubMed2004

Rhomboid muscle electromyography activity during 3 different manual muscle tests.

OBJECTIVE: To determine which of 3 previously published rhomboid manual muscle tests (MMTs) elicits the maximal rhomboid electromyographic activity in an asymptomatic population. DESIGN: Criterion standard. SETTING: Motion analysis laboratory at tertiary care medical center. PARTICIPANTS: Eleven male volunteers (age range, 24-40y) without shoulder or neck pain. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Peak 1-second normalized electromyographic activity in the rhomboid muscle during 8 different MMT positions, including 3 different rhomboid MMT positions (Kendall, Kendall-Alternative, Hislop-Montgomery). RESULTS: The Kendall MMT (78% maximal voluntary contraction [MVC]) produced higher rhomboid electromyographic activity than the Kendall-Alternative (71% MVC) or the Hislop-Montgomery MMT (52% MVC), but the differences were not statistically significant. The posterior deltoid MMT generated the greatest rhomboid electromyographic activity of all MMTs, and 4% to 30% greater rhomboid electromyographic activity than the 3 rhomboid MMTs (P=.0001; posterior deltoid > Hislop-Montgomery). Electromyographic profiles of the Kendall and Kendall-Alternative MMTs were similar, whereas the Hislop-Montgomery MMT produced less upper trapezius activity (P=.0001 vs Kendall and Kendall-Alternative) and more latissimus dorsi activity (P=.0001 vs Kendall-Alternative). The standard MMT positions for the middle trapezius, levator scapula, posterior deltoid, and latissimus dorsi produced the maximal electromyographic activity for their respective target muscles. CONCLUSIONS: The posterior deltoid MMT position should be used to produce maximal rhomboid electromyographic activity for normalization purposes during kinesiologic studies. The Kendall and Kendall-Alternative rhomboid MMT are likely to be clinically indistinct. It is unlikely that clinicians can use standard MMT positions to distinguish rhomboid strength from synergists, such as the levator scapula and middle trapezius muscle, for diagnostic purposes.

Adult↗
PubMed1995

Ankle inversion injury and hypermobility: effect on hip and ankle muscle electromyography onset latency.

OBJECTIVE: Changes in reflexes associated with chronically sprained ankles were examined by measuring the reflex response latency of hip and ankle muscles during instantaneous ankle/foot inversion. DESIGN: Randomized trials. SETTING: All studies were performed in the Research Department laboratories at a major rehabilitation center in a large metropolitan area. PATIENTS AND OTHER PARTICIPANTS: Twenty subjects were assigned to 2 groups (normal and hypermobile) based on goniometry testing. Subjects were recruited from hospital and University staff and had a mean age of 31 +/- 5 years. OUTCOME MEASURES: Subjects stood on a platform constructed such that either foot/ankle could be instantaneously inverted. Latency was measured by EMG surface electrodes placed over the right and left gluteus medius and peroneal muscles. Two-factor analysis of variance was calculated to determine significant muscle onset latency differences (p < .01) between groups. RESULTS: Significant EMG latency differences were found in comparing right gluteus medius of the hypermobile group (127.35 +/- 6.02msec) with the normal group (150.49 +/- 6.49msec) during right ankle perturbation, and the left gluteus medius of the hypermobile group (120.71 +/- 6.16msec) with the normal group (136.24 +/- 5.88msec) during left ankle perturbation. CONCLUSIONS: These data suggest that there is decreased latency of hip muscle activation after ankle inversion in the hypermobile population. In treating ankle instability, clinicians must decide to address the altered hip muscle recruitment pattern or accept this recruitment pattern as an injury-adaptive strategy and thus accept unknown long-term consequences of premature muscle activation (ie, possible articular predisposition to degenerative changes, altered joint reaction forces, and muscle imbalances).

Adult↗
PubMed1995

Relation between needle electromyography and nerve conduction studies in patients with carpal tunnel syndrome.

Four hundred eighty cases of electrodiagnostically confirmed carpal tunnel syndrome were reviewed to determine if the findings on nerve conduction studies could predict the presence or absence of fibrillation potentials or motor unit changes on the needle examination of the abductor pollicis brevis (APB). The needle examination is more uncomfortable and the ability to predict the findings in this setting from standard nerve conduction studies (NCS) would make the test more acceptable to patients. All patients had median and ulnar nerves (both sensory and motor) tested, as well as the needle evaluation of the APB. Two hundred thirty-one patients had an abnormal needle evaluation as defined by presence of one of the following conditions: abnormal spontaneous activity, increased motor unit action potential (MUAP) amplitude, or increased MUAP polyphasia. One hundred five patients had fibrillation potentials. The mean median motor and sensory amplitudes and latencies, as well as age, did differ in the normal and abnormal needle examination groups, but the sensitivity for predicting an abnormality ranged from 57% to 68%. The ratio of the median to the ulnar amplitudes did not improve the sensitivity of predicting the abnormal needle findings. Motor and sensory evoked potential latencies were the most important predictors of an abnormal needle examination.

Adolescent↗
PubMed1996

Electromyography.

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Electromyography↗
PubMed1996

Electromyography.

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Decision Making↗
PubMed1997

Gait electromyography in children with myelomeningocele at the sacral level.

OBJECTIVE: Patients with sacral level myelomeningocele can be expected to maintain a high level of ambulatory status long into adulthood. Gait deterioration and knee pain reported in this population may be attributed to compensatory movements and increased recruitment of less affected muscle groups to achieve this desired level of ambulation. The objective of this study was to analyze the effect of the solid ankle-foot-orthoses (AFOs) on the muscular activity of selected muscles during walking. DESIGN: Cohort/outcome. SETTING: Laboratory. PATIENTS: Twenty four patients with sacral level myelomeningocele between 4 to 17 years of age. INTERVENTION: Electromyographic activity of selected muscle groups were studied during barefoot walking and walking with solid AFOs at a self-selected walking velocity. MAIN OUTCOME MEASURES: Timing of electromyographic activity and sagittal plane knee kinematics. Comparison to normal electromyographic patterns and changes between barefoot and AFO walking conditions. RESULTS: With the AFOs there was significantly less prolonged stance phase quadriceps activity compared with barefoot walking, although greater than normal activity persisted. There was no change between conditions for the other monitored muscle groups. All muscles elicited greater duration of activity over the course of the gait cycle. CONCLUSIONS: Our results show that solid AFOs improve the prolonged knee extensor activity evident for barefoot walking. This is clinically relevant to the gait deterioration and knee pain sometimes seen in this patient population. We espouse early and persistent orthotic intervention to reduce compensatory muscular overactivity and maintain gait quality.

Adolescent↗
PubMed1996

A comparison of computer-based methods for the determination of onset of muscle contraction using electromyography.

Little consensus exists in the literature regarding methods for determination of the onset of electromyographic (EMG) activity. The aim of this study was to compare the relative accuracy of a range of computer-based techniques with respect to EMG onset determined visually by an experienced examiner. Twenty-seven methods were compared which varied in terms of EMG processing (low pass filtering at 10, 50 and 500 Hz), threshold value (1, 2 and 3 SD beyond mean of baseline activity) and the number of samples for which the mean must exceed the defined threshold (20, 50 and 100 ms). Three hundred randomly selected trials of a postural task were evaluated using each technique. The visual determination of EMG onset was found to be highly repeatable between days. Linear regression equations were calculated for the values selected by each computer method which indicated that the onset values selected by the majority of the parameter combinations deviated significantly from the visually derived onset values. Several methods accurately selected the time of onset of EMG activity and are recommended for future use.

Adolescent↗
PubMed1979

A new method for electromyography of the female urethra.

A newly developed catheter enables the introduction of fine wire electrodes into the urethral striated sphincter muscle at predetermined locations and depths. Because of FET-probes electrode wires can be short, thus the signals show minimal artifacts owing to cable movement. The technique 1) facilitates registration of signals during coughing, walking, micturition and other activities, 2) is simple to perform and painless to the patient, 3) can be done by inexperienced personnel and 4) provides assurance that the electrodes are in the urethral sphincter muscle.

Cough↗
PubMed1976

Combined electromyography and gas urethral pressure profilometry before and after transurethral resection of the prostate.

Combined electromyographic and gas urethral pressure profilometry was done on 10 consecutive patients before and 3 months after transurethral resection of the prostate. A significant reduction was found postoperatively in the functional urethral length, whereas the maximum urethral closure pressure remained unchanged. Increase in urethral resistance in prostatic obstruction of the posterior urethra was related to the increase in the functional length of the posterior urethra rather than to mechanical occlusion of the urethral lumen. Periurethral striated muscle activity was recorded from the membranous urethra to the urethrovesical junction with the maximal activity located in the membranous urethra. Marked striated muscle activity also was found consistently at the bladder neck.

Adenocarcinoma↗