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 379 records · Page 21Linked to original sources
PubMed2001

Surface electromyography-verified muscular damage associated with the open dorsal approach to the lumbar spine.

The dorsal approach is increasingly preferred in the surgical treatment of vertebral fractures. However, the access and the implant's position cause muscle loss, which can lead to instability and a reduced capacity for rehabilitation. Morphological factors (bones, intervertebral discs) are typically blamed for chronic pain syndromes in the literature, while less importance is attached to functional factors (muscles). The objective of this study was therefore to investigate the isolated influence of dorsal spinal instrumentation on the back muscles by means of electromyography (EMG). A total of 32 patients with conditions after dorsal spondylodesis following the fracture of a vertebral body and 32 subjects with healthy backs were enrolled in this study. The EMG signal was recorded in three different muscle groups during isometric extension exercise. The evaluation was performed by comparing the mean rectified amplitudes of the three muscle groups in the patients and controls. The patients had significantly lower amplitudes in the multifidus muscle (MF) and significantly higher amplitudes in the iliocostal muscle (IL). Patients with severe pain were found to have lower electric muscle potentials in all investigated muscle groups than patients with mild pain. The muscle damage which was established in the multifidus muscle is compensated by increased activity in the iliocostal muscle. On the basis of anatomical considerations, the damage pattern can be identified as having been caused by surgery. It is extremely unlikely that trauma is the cause.

Adolescent↗
PubMed2006

Trunk muscle activity in different modes of carrying schoolbags.

The daily load of carrying schoolbags is influenced by the mode of carriage. Electromyographic (EMG) activity from rectus abdominis and erector spinae was recorded bilaterally in five static conditions: no bag; shoulder bag; backpack; front pack; double pack. Nineteen students carried a load of 15% of their body weight. A double pack, with the load equally distributed in a front and a backpack, showed no significant differences in EMG activity compared with unloaded standing. The activity levels of erector spinae significantly decreased while carrying a backpack and increased with a shoulder bag and a front pack. Rectus abdominis revealed significantly higher EMG levels in the backpack trial. Asymmetrical activity between the right and the left part of the back muscles was clearly observed while carrying a shoulder bag with the weight at the right side of the body. The abdominal muscles revealed a slightly significant asymmetry for the shoulder bag and, surprisingly, also for the backpack. These findings suggest that the physical stresses associated with carrying book bags can be minimized by the design of a double pack. Asymmetry in muscle activity may indicate a failure of trunk stabilization and contribute to the development back pain.

Abdominal Muscles↗
PubMed2000

Lordosis of lumbar vertebrae in omphalocele: an important factor in regulating abdominal cavity capacity.

PURPOSE: Although it is well known that the tiny abdominal cavity associated with larger omphalocele enlarges rapidly after surgery, the responsible mechanism remains obscure. The authors have studied the curve of lumbar vertebrae and established a hypothesis in which lordosis of lumbar vertebrae plays a major role in changing the capacity of the abdominal cavity. METHODS: Fifty-three patients with intact omphalocele and 10 normal newborns as the control were studied. The size of omphalocele was determined from the mean value of the length and breadth of the sac. The curve of lumbar vertebrae (lordotic angle) was measured using Cobb's technique on the lateral radiograph serially taken in the supine position. RESULTS: The mean lordotic angle of 53 patients was 22.2 degrees (range, 0 to 65), which was significantly greater than 11.0 degrees of the control (P <.012). The individual lordotic angle before surgery was significantly correlated with the size of omphalocele (r = 0.668, P <.0001). In serial studies carried out in 15 patients with larger omphalocele, the mean lordotic angle was decreased significantly from 30.5 degrees to 20.0 degrees (P <.009) on the first postoperative day and returned to the control level within a few weeks. CONCLUSIONS: These results suggest that severe lumbar lordosis may well become an alternative factor to produce visceroabdominal disproportion observed before surgery, and its correction after surgery may well induce the abdominal cavity to rapidly enlarge. It may be speculated that the dehiscence of abdominal rectus muscles associated with omphalocele causes the tension of ventral muscles to decline, and, then, imbalance in tension between ventral (abdominal) and dorsal (back) muscles causes the lumbar lordosis to increase. Accordingly, at the staged procedure, the prosthetic sheet should be attached under moderate tension, and its plication should be carried out at regular intervals to maintain the tension of abdominal rectus muscles.

Hernia, Umbilical↗
PubMed1992

Regional changes in muscle mass following 17 weeks of bed rest.

This work reports on the muscle loss and recovery after 17 wk of continuous bed rest and 8 wk of reambulation in eight normal male volunteers. Muscle changes were assessed by urinary levels of 3-methylhistidine (3-MeH), nitrogen balance, dual-photon absorptiometry (DPA), magnetic resonance imaging (MRI), and isokinetic muscle performance. The total body lean tissue loss during bed rest calculated from nitrogen balance was 3.9 +/- 2.1 (SD) kg (P < 0.05). Although the total loss is minimal, DPA scans showed that nearly all of the lean tissue loss occurred in the lower limbs. Similarly, MRI muscle volume measurements showed greater percent loss in the limbs relative to the back muscles. MRI, DPA, and nitrogen balance suggest that muscle atrophy continued throughout bed rest with rapid recovery after reambulation. Isokinetic muscle strength decreased significantly (P < 0.05) in the thigh and calf with no loss in the arms and with rapid recovery during reambulation. We conclude that there is great variability in the degree and location of muscle loss in bed rest and that the lower limb muscles are primarily affected.

Absorptiometry, Photon↗
PubMed2002

The effect of massage on localized lumbar muscle fatigue.

BACKGROUND: There is not enough evidence to support the efficacy of massage for muscle fatigue despite wide utilization of the modality in various clinical settings. This study investigated the influence of massage application on localized back muscle fatigue. METHODS: Twenty-nine healthy subjects participated in two experimental sessions (massage and rest conditions). On each test day, subjects were asked to lie in the prone position on a treatment table and perform sustained back extension for 90 seconds. Subjects then either received massage on the lumbar region or rested for a 5 minute duration, then repeated the back extension movement. The median frequency (MDF), mean power frequency (MNF), and root mean square (RMS) amplitude of electromyographic signals during the 90 second sustained lumbar muscle contraction were analyzed. The subjective feeling of fatigue was then evaluated using the Visual Analogue Scale (VAS). RESULTS: MDF and MNF significantly declined with time under all conditions. There was no significant difference in MDF, MNF or RMS value change between before and after massage, or between rest and massage conditions. There was a significant increase in fatigue VAS at the end of the 2nd back extension with rest condition. There was a significant difference in fatigue VAS change between massage and rest condition. CONCLUSIONS: A significant difference was observed between massage and rest condition on VAS for muscle fatigue. On EMG analysis, there were no significant differences to conclude that massage stimulation influenced the myoelectrical muscle fatigue, which is associated with metabolic and electrical changes.

Adult↗
PubMed1996

Ecdysteroid mediated muscle actin synthesis during the larval development of rice moth, Corcyra cephalonica.

Protein fractions from the whole body homogenates were separated on SDS-PAGE and the muscle actin band was identified by western blotting, using commercial antibody raised against chick back muscle actin (Sigma Chemical Co., USA). The antibody was found to be specific for muscle actin, as it did not cross react with cytoplasmic actin of the nervous system. The molecular weight of the muscle actin in Corcyra was found to be around 46 kDa. The concentration of actin was found to be more or less the same in penultimate and early-last instar larvae and it increased during mid and late-last instar development. Thereafter, it has dropped to its minimum during the pupal stage. But, once again it increased to its maximum in adults. Thorax-ligation in early and late-last instar larvae resulted in decreased synthesis of muscle actin and this was more pronounced after 48 h of ligation. Injection of 20-hydroxyecdysone to insects which were thorax-ligated for 24 and 48 h was found to significantly increase the concentration of actin, suggesting that the ecdysteroids mediate the muscle actin synthesis during the larval development of Corcyra.

Actins↗
PubMed1976

The chemo-mechanical coupling relation in the oscillatory contraction-relaxation cycles of insect fibrillar muscle.

The mechanical properties and the activity of the myofibrillar ATPase have been investigated at 21 degrees C on glycerinated back muscle from the water-bug Lethocerus colossicus. When the fibres were held under isometric conditions after stretching them by 0.5--4%, the ATPase required to maintain a given tension increases from 19 to 39 p-moles ATP split for each mg of tension developed as the Ca2+ level is increased from 10(-7) to up to 10(-5) M. The mechanical properties and the ATPase activity have been determined for Ca2+-activated fibres using sinusoidal frequencies of 1--30 HZ and oscillatory amplitudes of 0.5--6% peak-to-peak. In this way the R.M.S. velocity of sinusoidal movement was varied between 0.1-10 mm/sec. The rate of ATP splitting associated with oscillatory tension development, the dynamic tension cost, increases both with Ca2+ and with frequency of oscillation (at 1% peak-to-peak amplitude), becoming as high as four times the isometric value. The oscillatory power output which can be obtained is increased when the Ca2+ level is raised from 10(-7) to 10(-5) M or towards higher amplitudes of oscillation. The chemo-mechanical coupling efficiency increases proportionally with the R.M.S. velocity of muscle movement. In presence of 10(-5) M Ca2+ optimal efficiencies of 5.5--6.2 kcal work per mole ATP split are obtained at R.M.S. velocities of 1.3--2 muscle lengths/sec. The ability of the muscle fibres to perform osciillatory work at the higher frequencies was much reduced at lower Ca2+ levels of 10(-6) or 10(-7) M and the maximal efficiencies never exceeded 2.2 kcal/mole.

Adenosine Triphosphatases↗
PubMed1985

The effect of backrest inclination, lumbar support and thoracic support on erector spinae muscles when lifting.

The effect of backrest inclination, lumbar support and thoracic support on the erector spinae muscle when lifting while sitting has been investigated. It was found that the lowest values of the iEMG of the back muscle were obtained when: (1) the lumbar support was positioned +4 cm forward, the thoracic support inclined to +10 degrees and the backrest inclination at 110 degrees; (2) the lumbar support was positioned +4 cm forward, the thoracic support inclined to +10 degrees and the backrest inclined to 100 degrees; (3) the lumbar support was positioned +1 cm forward, the thoracic support inclined to +10 degrees and the backrest inclination 110 degrees; (4) the backrest was inclined to 100 degrees the thoracic support inclined to 10 degrees and the lumbar support 1 cm forward; (5) the backrest inclination and lumbar support were both increased; (6) the thoracic support and the backrest inclination were both increased.

Adolescent↗
PubMed2004

Changes in recruitment of the abdominal muscles in people with low back pain: ultrasound measurement of muscle activity.

STUDY DESIGN: Ultrasound and electromyographic (EMG) measures of trunk muscle activity were compared between low back pain (LBP) and control subjects in a cross-sectional study. OBJECTIVES: To compare the recruitment of the abdominal muscles (measured as a change in thickness with ultrasound imaging) between people with and without low back pain and to compare these measurements with EMG recordings made with intramuscular electrodes. SUMMARY OF BACKGROUND DATA: Although ultrasonography has been advocated as a noninvasive measure of abdominal muscle activity, it is not known whether it can provide a valid measure of changes in motor control of the abdominal muscles in LBP. METHODS: Ten subjects with recurrent LBP and 10 matched controls were tested during isometric low load tasks with their limbs suspended. Changes in thickness from resting baseline values were obtained for transversus abdominis (TrA), obliquus internus (OI), and obliquus externus (OE) using ultrasonography. Fine wire EMG was measured concurrently. RESULTS: Study participants with LBP had a significantly smaller increase in TrA thickness with isometric leg tasks compared with controls. No difference was found between groups for OI or OE. Similar results were found for EMG. People with LBP had less TrA EMG activity with leg tasks, and there was no difference between groups for EMG activity for OI or OE. CONCLUSIONS: This study reinforces evidence for changes in automatic control of TrA in people with LBP. Furthermore, the data establish a new test of recruitment of the abdominal muscles in people with LBP. This test presents a feasible noninvasive test of automatic recruitment of the abdominal muscles.

Abdominal Muscles↗
PubMed1989

Labour pain: correlations with menstrual pain and acute low-back pain before and during pregnancy.

Low-back pain is a major component of labour pain in a substantial number of women. The purpose of this study was to determine whether episodes of acute low-back pain prior to pregnancy is a predictor of low-back pain during labour. 114 women received the Short-Form McGill Pain Questionnaire (SF-MPQ) during labour and were asked to describe the pain separately for front and back contraction pain or continuous pain. The day after the birth of the child the women were interviewed to determine whether they had (a) a history of episodes of acute low-back pain before pregnancy, (b) low-back pain during pregnancy, and (c) low-back pain during menstruation. The results show that episodic low-back pain before pregnancy is not correlated with any aspect of labour pain. However, it is significantly correlated with episodes of low-back pain during pregnancy. In contrast, low-back pain during menstruation is significantly correlated with labour pain scores recorded for back and front contraction pain as well as for continuous back pain. The significant correlation of labour pain with back pain during menstruation suggests that both share a common underlying mechanism. Similarly, the correlation of low-back pain during pregnancy with episodes of acute low-back pain before pregnancy suggests that the strain on back muscles during pregnancy may activate the mechanisms that underlie the usual forms of low-back pain.

Abdomen↗
PubMed1996

4-Chloro-m-cresol, a potent and specific activator of the skeletal muscle ryanodine receptor.

The aim of the present study was to determine the effects of 4-chloro-m-cresol (4-CmC), a preservative often added to drugs intravenously administered, on the skeletal muscle sarcoplasmic reticulum (SR) Ca2+ release channel/ryanodine receptor. In heavy SR vesicles obtained from rabbit back muscles, 4-CmC stimulated (Ca2+)-activated [3H]ryanodine binding with an EC50 of about 100 microM. In the same concentration range, 4-CmC directly activated the isolated Ca2+ release channel reconstituted into planar lipid bilayers. The sensitivity to 4-CmC was found to be higher when applied to the luminal side of the channel suggesting binding site(s) different from those of nucleotides and caffeine. In skeletal muscle fibre bundles obtained from biopsies of patients susceptible to malignant hyperthermia, a skeletal muscle disease caused by point mutations in the ryanodine receptor, 4-CmC evoked caffeine-like contractures. Contrary to caffeine which induces contractures in millimolar concentrations, the threshold concentration for 4-CmC was 25 microM compared to 75 microM for non-mutated control fibres. Since these data strongly indicate that 4-CmC specifically activates SR Ca2+ release also in intact cell systems, this substance might become a powerful tool to investigate ryanodine receptor-mediated Ca2+ release in muscle and non-muscle tissue.

Animals↗
PubMed2005

Effect of concrete block weight and wall height on electromyographic activity and heart rate of masons.

Work-related musculoskeletal disorders (MSDs) are common among construction workers, such as masons. Few interventions are available to reduce masons' exposure to heavy lifting, a risk factor for MSDs. The purpose of this study was to determine whether one such intervention, the use of light-weight concrete blocks (LWBs), reduces physiological loads compared to standard-weight blocks (SWBs). Using a repeated measures design, 21 masons each constructed two 32-block walls, seven courses (rows) high, entirely of either SWBs or LWBs. Surface electromyography (EMG), from arm and back muscles, and heart rate was sampled. For certain muscles, EMG amplitudes were slightly lower when masons were laying LWBs compared to SWBs. Upper back and forearm extensor EMG amplitudes were greater for the higher wall courses for both block weights. There were no significant differences in heart rate between the two blocks. Interventions that address block weight and course height may be effective for masons.

Adult↗
PubMed1995

Isovelocity investigation of the lengthening behaviour of the erector spinae muscles.

The purpose of this study was to investigate the force-velocity (F/v) relationship for the erector spinae muscles in submaximal activation movements, with particular attention to their response during lengthening movements and at lower shortening contraction velocities. Dynamic models that predict lower back muscle forces require reasonable representations of the modulating effect of instantaneous velocity. Ten males were observed performing trunk flexion and extension in the sagittal plane under constant load. Contraction velocities were measured as the first derivative from a devise sensitive to changes in spine curvature, and controlled by a visual feedback system while a constant load was applied through a chest harness. The erector spinae exhibited a yielding phenomenon which causes an abrupt drop in force during constant velocity stretching under constant, submaximal, stimulation. The findings were consistent with previous isovelocity muscle lengthening experiments. Yielding appeared dependent on the level of load/activation supporting the theory of a "state-variable" F/v relationship. The eccentric behaviour of the lower erectors (L3) seemed independent of velocity and length, while that of the upper erectors (T9) showed a dependence on length. At lower concentric velocities, concavity in torque-velocity curves was noted after a "threshold" velocity. The findings of this study strongly reinforce the notion that the F/v length relationship is not a continuous hyperbolic relationship during muscle shortening and that the commonly modelled force augmentation effect of lengthening is incorrect, at least for submaximal activation of the extensors of the lower back.

Adult↗
PubMed2003

Pain differs from non-painful attention-demanding or stressful tasks in its effect on postural control patterns of trunk muscles.

Pain changes postural activation of the trunk muscles. The cause of these changes is not known but one possibility relates to the information processing requirements and the stressful nature of pain. This study investigated this possibility by evaluating electromyographic activity (EMG) of the deep and superficial trunk muscles associated with voluntary rapid arm movement. Data were collected from control trials, trials during low back pain (LBP) elicited by injection of hypertonic saline into the back muscles, trials during a non-painful attention-demanding task, and during the same task that was also stressful. Pain did not change the reaction time (RT) of the movement, had variable effects on RT of the superficial trunk muscles, but consistently increased RT of the deepest abdominal muscle. The effect of the attention-demanding task was opposite: increased RT of the movement and the superficial trunk muscles but no effect on RT of the deep trunk muscles. Thus, activation of the deep trunk muscles occurred earlier relative to the movement. When the attention-demanding task was made stressful, the RT of the movement and superficial trunk muscles was unchanged but the RT of the deep trunk muscles was increased. Thus, the temporal relationship between deep trunk muscle activation and arm movement was restored. This means that although postural activation of the deep trunk muscles is not affected when central nervous system resources are limited, it is delayed when the individual is also under stress. However, a non-painful attention-demanding task does not replicate the effect of pain on postural control of the trunk muscles even when the task is stressful.

Abdominal Muscles↗
PubMed2006

Physical fitness profiles in young Finnish men during the years 1975-2004.

PURPOSE: This population-based study describes fitness profiles in aerobic capacity (N = 387088) during the years 1975-2004, muscle performance (N = 280285) from 1982 to 2003, and body anthropometry (N = 324911) from 1993 to 2004 among the Finnish conscripts at the age of 20 yr. METHODS: Endurance performance was tested by the 12-min running test. Muscle fitness tests consisting of sit-ups, push-ups, pull-ups, a back-muscle test, and standing long jump were scored to muscle fitness index (MFI). RESULTS: The mean body mass of the conscripts increased from 70.8 to 75.2 kg (P < 0.01) during the years 1993-2004. The mean distance of the conscripts" 12-min running test increased first by 4% from 1975 to 1979, but after it that decreased by 12% (from 2760 m to 2434 m, P < 0.001) compared with the year 2004. MFI increased during the first decade of the follow-up, but thereafter, the number of conscripts who achieved excellent and good MFI decreased from 66.8 to 41.2% (P < 0.001) during the years 1992-2004. The physical ability of the conscripts to meet military service declined during the last 15 yr. CONCLUSION: Both the increase in body mass and the decrease in physical fitness may lead to serious health problems in the future.

Adult↗
PubMed1998

Electromyographic response of the trunk muscles to postural perturbation in sitting subjects.

Electromyographic (EMG) patterns of the trunk muscles were investigated during balance perturbations in a sitting position. Five healthy subjects (two females and three males, mean age 24.4 yr) were seated on a platform allowing rotational perturbations in the frontal and sagittal planes. Each of the forward, backward, right and left perturbations were delivered with and without expectation at the velocities 8 degrees s-1 (SD +/- 4 degrees s-1) and 26 degrees s-1 (SD +/- 6 degrees s-1). The fast expected and unexpected perturbations were compared in blindfolded subjects. In the slow perturbations the effect of a blindfold on the balance reactions was tested. The root mean square (RMS) EMG signals from 12 trunk muscles were recorded and analysed to determine the EMG magnitudes. During the forward and backward rotations there was always a symmetrical EMG pattern between corresponding muscles on the right and left sides. A reciprocal phasic EMG activity between the left and right back muscles was found during frontal rotations. No reciprocal phasic activity was found in the abdominal muscles. Neither verbal instruction about the upcoming perturbation nor the blindfold changed the activation patterns.

Abdominal Muscles↗
PubMed2006

Adaptations in the walking pattern of spinal cord injured rats.

Walking ability is a measure of recovery used in many studies that test experimental strategies to treat injuries or diseases of the central nervous system (CNS) in animal models. A common measure in the rat animal model of thoracic spinal cord injury (SCI) is visual inspection and scoring of hind limb activity, which allows the documentation of movements associated with the recovery of locomotor function. In this study, we expand on previously documented visible changes in the locomotor pattern following SCI. The spontaneous recovery of locomotion in rats with thoracic SCIs of variable extent was evaluated using electromyographic (EMG) and kinematic analysis while rats walked on an elevated runway. Comparisons with pre-lesion walking sequences revealed changes in the kinematics and in the muscle activation pattern of various muscles, including enhanced fore limb extensor activity, possibly reflecting an increased contribution to propulsion, altered recruitment of back muscles inserting into the hip (possibly to support stepping movements), and elevated posture during stance, which may compensate for deficits in weight support. These changes were noted in spinal cord injured rats with varying degrees of impairment, including animals with no visually detectable deficit in open-field walking. In summary, the presented results demonstrate that spinal cord injured rats develop alternative locomotor patterns following SCI that cannot be discriminated by the use of qualitative visually based analysis, thus urging the use of quantitative outcome measures in assessing motor function after SCI.

Adaptation, Physiological↗