Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Back Muscles”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources
PubMed2001

Evaluation of physiological work demands and low back neuromuscular fatigue on nurses working in geriatric wards.

This study evaluated the physiological demands and low back neuromuscular fatigue patterns following a daytime work shift of 21 female nurses working in geriatric wards. Subjects' heart rate (HR) at work was monitored for 8 h and surface electromyogram (EMG) of their back muscle was recorded during a 1-minute horizontal trunk holding test before and after work. Results showed that the nurses had heart rates exceeding 90 beats/min in 57% and 110 beats/min in 19% of their working hours. The EMG revealed a significant drop in initial median frequency (MF) (p = 0.04) and increase in negative slope of the MF/time plot (p<0.001) of the back muscle after work. These suggest that the muscles were fatigued after work. The nurses rated patient lifting, transfer and turning as most physically demanding, and these corresponded to the highest heart rates recorded. The physiological and neuromuscular strain on the nurses indicated that extreme care should be exercised at work, particularly towards the end of a work shift when the muscles have become fatigued.

Adult↗
PubMed1984

Corrosion in metal implants embedded in various locations of the body in rats.

Corrosion in metal implants (stainless steel 316L) was followed up in 25 rats for periods of 1.5 to 14.0 months after insertion into the femur, back muscles, or as an external fixation of the tibia using light and scanning electron microscopy. In the implants buried in the back muscles and as an external fixation, mainly "face" and pitting corrosion were detected in 90% of the implants, while in the intramedullary implants crevice, pitting and various "holes" of irregular shape were evident in all implants. Calcium and phosphate deposits were also found on the intrafemoral implants. The corrosion in the implants was detected as early as 1.5 months but was quite variable. However, a progressive increase in the corrosion occurred concomitant with the length of time after implantation. The question is whether stainless steel metal implants presently in clinical use can be considered innocuous.

Animals↗
PubMed2003

Calcitonin gene-related peptide immunoreactive neurons with dichotomizing axons projecting to the lumbar muscle and knee in rats.

Dorsal root ganglion (DRG) neurons with dichotomizing axons have been reported in several species and are thought to be related to referred pain. However, these neurons, which have dichotomizing axons to the lumbar muscles and to the knee, have not been investigated. Clinically, pain from the lumbar muscles is sometimes referred to the lower extremities. Two kinds of neurotracers [1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (DiI) and fluoro-gold (FG)] were used in the present double-labelling study. DiI crystals were placed in the left lower back muscle, and FG was applied to the medial side of the knee. Bilateral DRGs from L1 through L6 were immunoreacted with calcitonin gene-related peptide (CGRP) antibodies and observed under a fluorescence microscope. DRG neurons double-labelled with DiI and FG were recognized only in the ipsilateral DRGs from levels L1 to L6. Approximately 1% of DRG neurons innervating the low back muscles had other axons to the medial side of the knee. In double-labelled neurons, the ratio of CGRP-immunoreactive DRG neurons was 60%. This finding provides a possible neuroanatomical explanation for referred knee pain from the lower back since CGRP is a marker of sensory neurons typically involved with pain perception. However, these neurons are rare, and mechanisms of referred pain may be explained by the convergence-projection hypothesis.

Animals↗
PubMedDate not supplied

Median frequency estimates of paraspinal muscles: reliability analysis.

The technique of monitoring the frequency shift of the electromyographic signal through a single parameter, the median frequency (MF), was investigated with regard to its reliability characteristics as tested on two back muscle groups: the multifidus and iliocostalis lumborum. The proportion of variance in the MF parameters accounted for by the test/retest reliability as well as by the left versus right side analysis is satisfactory for the multifidus, it is, however, consistently lower for the iliocostalis. For the purpose of measuring muscular function, the MF recording technique appears to be well suited for clinical research, its application in the assessment of muscular dysfunction of back muscles is nevertheless far from simple.

Adult↗
PubMed2007

Dynamic surface electromyographic responses in chronic low back pain treated by traditional bone setting and conventional physical therapy.

OBJECTIVE: This study compared the dynamic surface electromyographic (EMG) activities of back muscles and pain before and after traditional bone setting and physical therapy. METHODS: This study was a prospective clinical trial that compared surface EMG dynamic activities after traditional bone setting and physical therapy. Sixty-one patients (mean age, 41 years) with nonspecific low back pain were randomized into two subgroups by treatment. The patients underwent a dynamic EMG evaluation for which they were asked to stand and then bend forward as far as possible, stay fully flexed, and return to standing. A flexion-relaxation ratio was calculated by comparing maximal EMG activity while flexing with the average EMG activity in full flexion. Concentric (maximal EMG activity during extension) and eccentric (maximal EMG activity during flexion) ratios were also used in the analyses. RESULTS: Disability, depression, and visual analog scale scores decreased significantly after both treatments. The concentric ratio increased statistically in both groups after the treatments. The study failed to show a significant association between experienced back pain and EMG parameters. CONCLUSIONS: Both treatments seem to have a positive influence on back muscle function by improving muscle symmetry; however, the treatments had no effect on the flexion-relaxation phenomenon after 1 month. Active back exercise at home together with rehabilitation treatments might be effective and improve function for patients with chronic low back pain.

Adult↗
PubMed1997

Relationships between myoelectric activity, strength, and MRI of lumbar extensor muscles in back pain patients and normal subjects.

Eight normal individuals and eight patients with chronic back pain were evaluated. They undertook a treatment program lasting 8 weeks, with two exercise sessions each week. Myoelectric activity, lumbar extensor strength, and cross-sectional magnetic resonance imaging appearance of the lumbar paraspinal extensor muscles was assessed at the beginning and end of the program. Initial baseline and final extensor strength measurements were done isometrically at seven points through full range. Surface myoelectric activity was monitored during both flexion and extension exercise. Subsequently, electromyographic (EMG) signals were analyzed for mean frequency (MPF) and amplitude (RMS). An average functional improvement of 65% and reduction of pain complaint of 41% occurred in the eight patients with chronic low back pain. Extensor strength improved an average of 48% contrasted to 6% for the normal subjects. Four patients who showed severe fatty infiltration in the extensors had a decrease in the degree of infiltration and no change in muscle mass. Changes in fatty infiltration did not correlate with strength changes. The dynamic EMG changes documented a decrease in amplitude (RMS) and a smaller decrease in frequency (MPF) for the same resistance when used at the beginning and end of the program. Structural changes in the muscles are not always needed to achieve strength gains or symptomatic improvement.

Back Pain↗
PubMed2000

Vestibular deprivation and the development of dendrite bundles in the rat.

Motoneuronal pools of muscles that subserve postural tasks contain dendrite bundles. We investigated in the rat the development of these bundles in the pools of the long back muscles and related this to postural development. Motoneurons and their dendrites were retrogradely labeled by injecting unconjugated cholera toxin subunit B (CTB) into the muscles of 54 normal rats from birth until adulthood and into 18 rats that were vestibularly deprived from the 5th postnatal day (P5). Dendrite bundles coursing in a transverse direction already occurred at P1. From P4, the first longitudinal bundles could be observed, but the major spurt in development occurred between P6 and P9, when conspicuous bundles developed coursing in rostro-caudal and transverse directions. This is the age when rats become able to stand freely and walk a few steps. Around P20, the dendrite bundles attained their adult characteristics. Vestibular deprivation by plugging both semicircular horizontal canals did not lead to a retarded development of dendrite bundles nor to a changed morphology. This finding is remarkable, as behavioral analysis showed a delay in postural development by about 3 days. We hypothesize that dendrite bundles in the pools of the long back muscles function to synchronize the motoneurons in different spinal cord segments.

Acoustic Stimulation↗
PubMed2006

Trunk muscle activation patterns during walking at different speeds.

Investigations of trunk muscle activation during gait are rare in the literature. As yet, the small body of literature on trunk muscle activation during gait does not include any systematic study on the influence of walking speed. Therefore, the aim of this study was to analyze trunk muscle activation patterns at different walking speeds. Fifteen healthy men were investigated during walking on a treadmill at speeds of 2, 3, 4, 5 and 6 km/h. Five trunk muscles were investigated using surface EMG (SEMG). Data were time normalized according to stride time and grand averaged SEMG curves were calculated. From these data stride characteristics were extracted: mean SEMG amplitude, minimum SEMG level and the variation coefficient (VC) over the stride period. With increasing walking speed, muscle activation patterns remained similar in terms of phase dependent activation during stride, but mean amplitudes increased generally. Phasic activation, indicated by VC, increased also, but remained almost unchanged for the back muscles (lumbar multifidus and erector spinae) between 4 and 6 km/h. During stride, minimum amplitude reached a minimum at 4 km/h for the back muscles, but for internal oblique muscle it decreased continuously from 2 to 6 km/h. Cumulative sidewise activation of all investigated muscles reached maximum amplitudes during the contralateral heel strike and propulsion phases. The observed changes argue for a speed dependent modulation of activation of trunk muscles within the investigated range of walking speeds prior to strictly maintaining certain activation characteristics for all walking speeds.

Abdominal Muscles↗
PubMed2004

Electromyographic study of trunk muscle activity during unresisted twisting posture in various twisting angles.

The study investigated muscular activities of trunk twisting during standing posture by observing the surface EMG signal to estimate which muscles were active in graded isometric twisting posture. A laser pointer was used to maintain the twisting angle, while external resistances, which were commonly used to maintain the posture, were avoided. This procedure approached actual working posture in real life. Grading postural effort into various twisting angles provided reliable and natural posture measurements. Erector spinae (ES) at levels of L2 and L5 were selected to represent low back muscles, while external oblique (EO) and internal oblique (IO) were represented as abdominal muscles. Ten male subjects were asked to maintain a trunk twisting posture in various twisting angles for each right and left twisting direction. The EMG of the observed muscles were analyzed by power spectral density, and the activity changes were normalized by procedures of relative presentation and standardization. A Tukey multiple comparison was also applied to compare the activity changes among postural stages. Higher activity in contralateral ES, contralateral EO and ipsilateral IO is shown in the results, however, a significant increase against the initial posture (i.e., no-twisting posture) was found when the twisting angle was more than 30 degrees. Consistency with most past studies was shown in the result for the muscular activity of abdominal muscles, but not in the results for the low back muscles. The result emphasized the consideration that trunk muscle activity under a natural twisting condition was not always the same as that with the twisting under external resistance.

Abdominal Muscles↗
PubMed2001

Intermittent isometric fatigue study of the lumbar multifidus muscle in four-point kneeling: an intra-rater reliability investigation.

Back muscle endurance is considered important in low back pain (LBP) rehabilitation. Specific training of multifidus may also be necessary to restore normal low back function. The reliability of surface electromyogram (EMG) to assess endurance of the multifidus muscle during intermittent isometric exercise was evaluated. Multifidus endurance was monitored in the four-point kneeling exercise position using the power spectral analysis method. Twenty healthy volunteers were tested on three separate occasions. Subjects performed repeat 10 s high-intensity voluntary contractions of multifidus for 3 min. The median frequency (MF) and the integrated-rectified (I-R) EMG signal displayed the fatigue pattern of multifidus. Intraclass correlation coefficients indicated fair-good reproducibility for MF (0.48-0.67) but poor reliability for IR-EMG. In conclusion, problems concerning functional testing protocols for the back muscles remain and careful development is necessary for more realistic rehabilitation monitoring.

Adult↗
PubMed2001

Effect of LSD on prepulse inhibition and spontaneous behavior in the rat. A pharmacological analysis and comparison between two rat strains.

The goal of the present study was to better delineate the mechanisms of action of the prototypical hallucinogen LSD. LSD (0.03, 0.1 and 0.3 mg/kg, s.c.) produced locomotor hyperactivity, disruption of PPI and a number of behaviors indicative of 5-HT activation such as wet-dog shakes, back muscle contractions and forepaw treading. These various behavioral effects of LSD were studied in both Sprague-Dawley and Wistar rats, although with the exception of back muscle contractions which were more prominent in Sprague-Dawley rats, no major strain differences were detected. The PPI disruption induced by LSD (0.1 mg/kg) in Sprague-Dawley rats was completely reversed by pretreatment with the selective 5-HT(2A) antagonist MDL 100907 (0.5 and 1 mg/kg, s.c.). In contrast, pretreatment with antagonists at 5-HT(2C), (SB 242084 (0.5 mg/kg, i.p.)); 5-HT(2B/2C) (SDZ SER 082 (1 mg/kg, s.c.)); 5-HT(1A), ((+)-WAY 100135 (1 and 20 mg/kg, s.c.)) and 5-HT(6) receptors, (RO 04-6790 (30 mg/kg, i.p.)), all failed to influence LSD-induced disruption of PPI. The dopamine DA(2like) receptor antagonist, haloperidol (0.1 and 0.2 mg/kg, s.c.), was without effect against an LSD-induced disruption of PPI. Finally, selective blockade of 5-HT(2A) but not 5-HT(2C) receptors completely abolished the locomotor hyperactivity induced by LSD. These findings provide empirical evidence to support the view that the hallucinogenic effects of LSD are mediated by a direct agonist effect at 5-HT(2A) receptors.

Animals↗
PubMed1988

Commonly adopted postures and their effect on the lumbar spine.

The activity of the erector spinae muscles and the changes in lumbar curvature were measured in 11 subjects in a range of commonly adopted postures to see if there were any consistent trends. Surface electrodes were used to measure back muscle activity and lumbar curvature was measured using electronic inclinometers. The results showed that many commonly adopted postures reduced the lumbar lordosis when compared with erect standing or sitting, even at the expense of increasing the back muscle activity.

Adult↗
PubMed1988

Instability in human forearm movements studied with feed-back-controlled muscle vibration.

1. Frequency-modulated vibration was applied to the elbow flexor and extensor tendons to produce reflex movements of the forearm in normal subjects. The modulating (command) signal caused equal and opposite deviations from the 40 Hz carrier frequency so that when flexor vibratory frequency increased, extensor frequency decreased, and vice versa. 2. It is argued that the movements resulted largely from the reflex action of muscle spindle primary afferents whose firing frequency had been 'taken over' and modulated by the vibration. 3. Bode plots relating forearm movements to command signal (modulating) frequency showed the transfer function of the Ia afferent-CNS-muscle-load system to have a low-pass filter characteristic. The phase lag of movement on command increased progressively with command signal frequency, exceeding 180 deg at 3-4 Hz. 4. The transduced forearm movements were fed back to provide the command signal to the vibrators (and thus indirectly to the spindle afferents) via a filter mimicking the dynamic responsiveness of muscle spindle primary endings. Our aim was to 'break into' the reflex arc, and re-route it so that we could artificially vary the gain without significantly altering the dynamics of the pathway. 5. Nearly all subjects developed forearm oscillations (tremor) when the gain exceeded a threshold value. Subjects varied widely in their threshold, though for a given subject the threshold remained fairly constant from day to day. The results suggest that reflexly active individuals may not have a large safety margin with respect to forearm instability. 6. The frequency range of the oscillations observed in seven subjects was 3-8 Hz. The frequencies depended upon the level of flexor-extensor co-contraction, and increased from 3 to 5 Hz at 10% co-contraction to 5-8 Hz at 100% co-contraction. An analysis of the mechanical impedance of the arm provided estimates of tremor frequencies consistent with these results. 7. These unexpectedly low tremor frequencies led us to propose that it may be erroneous to expect stretch reflexes to contribute to forearm tremor in the range 8-12 Hz (e.g. physiological and 'enhanced' physiological tremors). Rather, their contributions should be sought in the range 3-8 Hz (e.g. pathological tremors such as those of Parkinson's and cerebellar disease).

Action Potentials↗
PubMed2006

Effects of different levels of torso coactivation on trunk muscular and kinematic responses to posteriorly applied sudden loads.

BACKGROUND: Studies examining rapid spine loading have documented the influence of steady-state trunk preloads, and the resulting levels of trunk muscle preactivation, on the control of spine stability. However, the effects of different levels of muscle coactivation, and resulting spine loads, on the response to a perturbation of the externally unloaded trunk are unclear. METHODS: Fourteen male subjects coactivated the abdominal muscles at four different levels (approximately 0%, 10%, 20% and 30% of the maximal voluntary contraction) monitored by an electromyography biofeedback system while semi-seated in a neutral lumbar spine position. They were loaded posteriorly in two directions (0 degrees and 30 degrees from the sagittal plane) and with two different loads (6.80 and 9.07 kg). Force perturbation, spine displacement and electromyography activity were measured, and torso compression and stability were modeled. FINDINGS: Abdominal coactivation significantly increased spine stability and reduced the movement of the lumbar spine after perturbation, but at the cost of increasing spinal compression. Preactivation also reduced the frequency and magnitude, and delayed the onset of muscle reactions, mainly for the back muscles and the internal oblique. The higher magnitude load and the load applied in an oblique direction both showed more potentially hazardous effects on the trunk. INTERPRETATION: Torso coactivation increases spinal stiffness and stability and reduces the necessity for sophisticated muscle responses to perturbation. Although further investigation is needed, it appears there is an asymptotic function between coactivation and both stiffness and stability. There also appears to be more hazard when buttressing twisting components of a sudden load compared to sagittal components. Patients with trunk instability and intolerance to spine compression may benefit from low to moderate levels of coactivation.

Abdominal Muscles↗
PubMed1992

A new paradiscal injection technique for the relief of back spasm after chemonucleolysis.

Back spasm, or spasm of the back muscles, is the commonest adverse reaction encountered after chemonucleolysis. In order to overcome this troublesome complication, the authors present a new 'paradiscal injection technique'. After the injection of chymopapain into the affected disc, the needle is withdrawn to just outside the annulus. Bupivacaine is injected into the paradiscal 'space' which acts upon the paravertebral muscles. Eighty consecutive patients have been treated by chemonucleolysis with paradiscal injection for pain relief. All patients were discharged the same day or the following day and no immediate complications occurred. When reviewed 3 weeks later, only three (3.8%) patients complained of back pain (which was different in character to that present before the injection or was exacerbated by the injection). Pain persisted in the same patients until 6 months after the injection but was negligible. None of the remaining patients had developed back pain as a result of chymopapain. The authors suggest that the addition of paradiscal injection of bupivicaine after cymopapain injection can reduce the incidence of spasm of the back muscles. This technique is a major contribution to increasing the efficacy of chemonucleolysis for the treatment of herniated lumbar disc.

Adult↗
PubMed1990

Zinc status in patients with idiopathic scoliosis.

The zinc content in m. sacrospinalis, hair, leukocytes of peripheral blood, and in serum was examined in 50 patients with idiopathic scoliosis treated by Harrington instrumentation. A control group included 20 patients treated for spinal column injury. A significant decrease of zinc content in back muscles was observed in patients with scoliosis. The value of zinc in hair, leukocytes, and serum did not differ compared with the control group. Similarly, the potassium and magnesium content in muscle was the same in both groups. These results do not suggest that there is a primary zinc deficiency in patients with idiopathic scoliosis. The authors consider the decreased zinc content in back muscle of patients with idiopathic scoliosis to be a secondary disturbance associated with primary deformation of the spinal column.

Adolescent↗
PubMed1976

Shoulder muscle tenderness and physical features of female industrial workers.

Physique, muscle strength, and jump-step scores of female industrial workers, ages 17--34, were studied in relation to tenderness of shoulder muscles for five groups, (A) character display operators, (B) fluorescent lamp assemblers, (C) photographic film rolling workers, (D) teachers and nurses of handicapped children, and (E) office workers. No significant differences were found between the five groups in mean body height, body weight, and skinfold thickness, but mean knee extension force of groups A and C and mean back muscle strength of groups A, B, and C was significantly lower than that of group E. Workers of groups C and D with a low tenderness threshold of m. trapezius of 0.6 kg/cm2 or less had stiff shoulders more frequently and lower force levels of knee extension, back muscle, and upper arm abduction than those without tenderness. No similar tendency was found for groups B and E. Further, among workers with objective signs of occupational cervicobrachial disorder, there were few whose knee extension force or jump-step scores were above the averages of normal office workers. Shoulder muscles of such operators were revealed to be continuously contracted during operations. The possible effects of chronic fatigue due to repetitive operations on developing localized tenderness and occupational hazards are discussed.

Adolescent↗
PubMed2005

Disability, pain, psychological factors and physical performance in healthy controls, patients with sub-acute and chronic low back pain: a case-control study.

OBJECTIVE: To compare measures of disability, psychological factors, pain and physical performance in healthy controls, and patients with sub-acute and chronic low back pain. To evaluate the concept of the deconditioning syndrome and to explore factors that may contribute to chronicity. DESIGN: Case-control study. SUBJECTS: Three age- and gender-matched groups were included in the study; healthy controls (n = 45), patients sick-listed 8-12 weeks (n = 46) and patients with chronic low back pain on a waiting list for lumbar instrumented fusion (n = 45). METHODS: Measures of disability, pain, psychological factors, and physical performance were obtained from the 3 groups using validated measures. RESULTS: Gender, age, body weight and height were not significantly different between the groups. Comparable scores were found for self-rated working ability, fear-avoidance beliefs for physical activity and aerobic capacity in the 2 patient groups. Oswestry Disability Index, pain, emotional distress, abdominal and back muscle endurance were significantly different between the 3 groups. Self-efficacy for pain and fear-avoidance beliefs for work was significantly different between the 2 patient groups. CONCLUSION: The results suggest a stepwise deterioration of impairment and disability from healthy controls to patients with chronic low back pain. Most variables distinguished between healthy controls and patients with sub-acute or chronic low back pain. Deconditioning was more related to psychophysical measures of abdominal and back muscle endurance than to cardiovascular fitness. Comparable scores for fear-avoidance and working ability in the 2 patient categories suggest that these factors appear at an early stage and contribute to the transition from acute to chronic low back pain.

Adult↗