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PubMed2006

Changes in muscle T2 relaxation properties following spinal cord injury and locomotor training.

Magnetic resonance (MR) is frequently used to study structural and biochemical properties of skeletal muscle. Changes in proton transverse relaxation (T2) properties have been used to study muscle cellular damage, as well as muscle activation during exercise protocols. In this study, we implemented MR imaging to characterize the T2 relaxation properties of rat hindlimb muscles following spinal cord injury (SCI) and locomotor training. After moderate midthoracic contusion SCI, Sprague-Dawley rats were assigned to either treadmill training, cycle training or an untrained group. T2 weighted images were obtained and mean muscle T2 times were calculated in the tibialis anterior, soleus, and gastrocnemius (GAS) muscles at pre-injury as well as at 1, 2, 4, 8, and 12 weeks post-injury. Following SCI, hindlimb muscles in untrained animals showed a significant increase in muscle T2, with the most dramatic shift (+5.46 ms) observed in soleus muscle at 1 week post-SCI. Subsequently, all muscle groups showed a spontaneous recovery in muscle T2 with normalized T2 values in the GAS and tibilias anterior muscles at 4 weeks and the soleus at 12 weeks post-SCI. Both training paradigms, treadmill and cycling training, accelerated the recovery of soleus muscle T2. As a result, soleus muscle T2 recovered back to pre-injury values within 3 weeks of training in both training groups. Finally, in vitro histological assessments of rat skeletal muscles demonstrated that there was no apparent muscle injury in any of the muscles studied at 1 week post-SCI.

Animals↗
PubMed1986

[The stiff man syndrome].

A 41-year-old patient with the rigidity syndrome was observed. The disease was expressed in marked rigidity of the long muscles of the back forming a picture of persistent hyperlordosis which led to a considerable disablement of the patient. Another complaint was spasms of the femoral muscles. A four-year follow-up of the patient revealed periodically recurring ataxia, nystagmus, and dysarthria. The patient benefited by relanium (diazepam) administration. On the basis of the literature data and a clinical analysis of this case the authors review clinical, differential-diagnostic, pathogenetic and etiological aspects of the rigidity syndrome.

Adult↗
PubMed2003

Mobile submuscular mass resembling a hard-boiled egg: case report.

A 68-year-old woman had a rare mobile mass on her back. The mass was similar to encapsulated fat necrosis except for its unusual stalked appearance, large size, and high degree of mobility underneath the anterior serratus muscle on the back. Based on previous descriptions of encapsulated fat necrosis, the clinical presentation of the mass might be regarded as an extreme example of this rare condition.

Aged↗
PubMed2004

The influence of different unloading positions upon stature recovery and paraspinal muscle activity.

OBJECTIVE: To determine whether stature recovery and paraspinal muscle activity can be altered in individuals with and without chronic low-back pain by assuming different unloading positions. DESIGN: A case-control study considering the effects of unloading position on stature recovery in individuals with and without chronic low-back pain. BACKGROUND: Stature recovery has been documented to be lower in individuals with chronic low-back pain. Elevated paraspinal muscle activity subjects the spine to increased compression, which may delay stature recovery. However, the mechanism(s) causing prolonged stature recovery are yet to be explored. METHODS: Eleven chronic low-back pain participants (age 33 yr (SD 12.2), height 1.72 m (SD 0.08), body mass 75.9 kg (SD 10.7)) and eleven asymptomatic participants (age 30.5 yr (SD 9.7), height 1.75 m (SD 0.10), body mass 73.3 kg (SD 11.7)) performed a loaded walking task (10% body mass) and adopted four unloading positions on separate occasions. Measurements of stature and muscle activity were recorded during each position. FINDINGS: Individuals with chronic low-back pain exhibited higher paraspinal EMG and delayed stature recovery in all positions (P<0.05). Both groups experienced greatest stature recovery and least muscle activity during gravity inversion (P<0.05). INTERPRETATION: Elevated muscle activity was found in the chronic low-back pain group supporting the existence of this explanation for delayed stature recovery. The gravity inverted position resulted in the lowest EMG and the greatest stature recovery. Further research is required to determine whether improving stature recovery has clinical implications by reducing pain/disability.

Adaptation, Physiological↗
PubMed1998

Patterns of bursting occurring in thalamic cells during parkinsonian tremor.

It has been proposed that parkinsonian tremor is produced either by the activity of an intrinsic thalamic pacemaker or by the oscillation of an unstable long loop reflex arc. The former (central) hypothesis proposes that overactivity of neurons in the internal segment of the globus pallidus inhibits or hyperpolarizes thalamic neurons. When hyperpolarized, thalamic cells oscillate with bursting of the type associated with low threshold calcium spikes (low threshold spike-bursts). Low threshold spike-bursts can be identified by particular patterns of interspike intervals within the burst. The alternative (peripheral) hypothesis proposes that tremor results from oscillation of a reflex arc transmitting activity from muscle stretch receptors to thalamus, motor cortex, and back to the stretched muscle. When the gain of this reflex is increased, the arc may become unstable and oscillate. Oscillations produced by peripheral inputs may produce an acceleration-deceleration pattern within the burst which results in sinusoidal modulation of a spike train if bursting is periodic. We have assessed these two hypotheses by studying the pattern of interspike intervals occurring within bursts recorded in patients with parkinsonian tremor. The spike trains were analysed for 118 cells located in the ventral nuclear group including ventralis intermedius (thalamic cerebellar relay nucleus, n=48) and ventralis oralis posterior (thalamic pallidal relay nucleus, n=39) of patients with parkinsonian tremor. Two cells recorded in ventralis intermedius of a sleeping patient with chronic pain showed bursting activity similar to the low threshold spike-bursts recorded in sleeping animals, suggesting a common mechanism for low threshold spike-bursts across species. Forty-two cells recorded in patients with parkinsonian tremor (ventralis intermedius, n=19; ventralis oralis posterior, n=12) were classified as tremor-related cells because their activity was characterized by both a concentration of power at tremor frequency and significant correlation with tremor. Eleven tremor-related cells, 10 located in ventralis intermedius or ventralis oralis posterior and most responding to sensory inputs, had an acceleration-deceleration pattern of intraburst firing. Only one cell, a tremor-related cell in ventralis intermedius, showed the pattern expected of presumed low threshold spike-bursts. Therefore, intraburst interspike interval patterns consistent with either the central or the peripheral hypothesis were recorded in the thalamus of patients with parkinsonian tremor. Twenty-one tremor-related cells (15 cells in ventralis intermedius or ventralis oralis posterior) had bursts with intraburst interspike intervals which were independent of position of the interspike interval within the burst. Therefore, the activity of the majority of cells was not consistent with either hypothesis, suggesting that another oscillatory process may contribute to parkinsonian tremor.

Electromyography↗
PubMed1995

Back pain in young athletes. Significant differences from adults in causes and patterns.

OBJECTIVES: To determine whether there are significant differences in the causes of back pain in young athletes compared with the general adult population and to review the diagnosis and assessment of young athletic adolescent patients who present with this complaint. DESIGN: Retrospective randomized case comparison study with two cohorts segregated by age and type of activity. SETTING: The adolescent sports medicine clinic of a children's hospital compared with the acute low back pain clinic of an orthopedic hospital. PATIENTS: One hundred adolescent athletes (aged 12 to 18 years; mean age, 15.8 years) with a chief complaint of low back pain were compared with 100 adults (aged 21 to 77 years; mean age, 31.9 years) with acute low back pain. INTERVENTIONS: None. MAIN OUTCOME MEASURES/RESULTS: Sixty-two percent of the adolescents had derangements of their posterior elements associated with the onset of back pain. Forty-seven percent of the 100 adolescents were ultimately shown to have a spondylolysis stress fracture of the pars interarticularis. By contrast, 5% of adult subjects were found to have spondylolysis associated with low back pain. Similarly, discogenic back pain was the final diagnosis in 48 of the 100 subjects in the adult group, while 11 of the 100 in the adolescent group had back pain attributable to disc abnormalities. Muscle-tendon strain accounted for back pain in 27% of the adults, while only 6% of the adolescents were diagnosed as having muscle-tendon strain. These differences were significant. Spinal stenosis and osteoarthritis as causes of back pain were encountered in 10% of the adults, while these conditions were not encountered in the children. CONCLUSIONS: There is a significant differences in the major causes of low back pain in young athletes compared with causes of low back pain in the general adult population. Physicians diagnosing back pain in young athletes must have a specific understanding of these differences to avoid incorrect diagnosis and harmful delays in proper treatment.

Adolescent↗
PubMed2002

Examination of the flexion relaxation phenomenon in erector spinae muscles during short duration slumped sitting.

OBJECTIVE: The purpose of this study was to examine the myoelectric activity of the erector spinae muscles of the back in order to determine if the flexion relaxation phenomenon occurs in seated forward flexion or slumped postures. BACKGROUND: The flexion relaxation phenomenon during standing forward flexion is well documented. However, flexion relaxation in seated forward flexion has not been studied. It is possible that flexion relaxation could be linked with low back pain that some individuals experience during seated work. METHODS: Twenty-two healthy subjects (11 males, 11 females) participated in the study. Surface electromyography was used to measure the level of muscle activity at the thoracic and lumbar levels of the erector spinae muscles. An electromagnetic tracking device measured the three-dimensional movement of the lumbar spine. Five trials each of standing and seated forward flexion were performed. RESULTS: A slumped sitting posture yielded flexion relaxation of the thoracic erector spinae muscles, whereas the lumbar erector spinae muscle group remained at relatively constant activation levels regardless of seated posture. Thoracic erector spinae silence occurred at a smaller angle of lumbar flexion during sitting than the flexion relaxation angle observed during standing flexion relaxation. CONCLUSIONS: Since the myoelectric activity of the lumbar erector spinae did not increase, it is likely that the passive tissues of the vertebral column were loaded to support the moment at L4/L5. Ligaments contain a large number of free nerve endings which act as pain receptors and therefore could be a potential source of low back pain during seated work. RELEVANCE: Examination of flexion relaxation during seated postures may provide insight into the association between low back pain and seated work.

Adult↗
PubMedDate not supplied

Job evaluation in worker fitness determination.

To assess work fitness on a placement exam requires detailed assessment of repetitive manual capabilities specific for the job, ability to withstand static loading of the back and other muscle groups in the working position, and tolerance of the heat and humidity conditions of the work environment. Less specific tests, such as aerobic capacity stress tests, grip strength, and back examination may not accurately reflect the demands of repetitive job activities and, therefore, may not satisfy the legal requirements of Title VII. Only occasionally will a job analysis lead to the establishment of a concrete capacity standard against which a potential worker's fitness or risk for injury can be measured in the physician's office. The most valuable contributions of a careful, quantitative job analysis are likely to be the identification of particular anatomic structures (e.g., joints and muscles) that will be subjected to high stress and a clear understanding of the job so that reasonable accommodation of the worker or modifications of the job and workplace can be considered. In summary, the following observations can be made: 1. Intensity of effort, continuous duration of effort, and frequency of repetition are the key factors for evaluating the physical demands on muscle groups during work. 2. Intensity of effort can be estimated by using psychophysical scaling techniques and by obtaining ratings from several people. 3. Timing the effort and recovery times for specific muscle groups during a task of interest can be used to quantify the possible fatigue. It will also provide information about ways to improve the task to bring it within the capabilities of more people. 4. Total workload is most easily evaluated by using estimation methods or lists of comparable jobs and then performing a time-weighted calculation of the full shift's work requirements. The workload should be related to the aerobic capacities of the active muscles. 5. Environmental heat and humidity reduce work capacity and must be factored into any assessment of job suitability. 6. Psychological and perceptual job demands should be assessed by defining the requirements for multiple-task performance or monitoring and by evaluating the environment for visual or auditory work. Accountability without control in the job should also be identified. 7. Many of the factors that make jobs difficult can be remedied without extensive cost to the employer. The job-evaluation techniques given in this chapter can help to identify the most effective ways to make changes in the job requirements.(ABSTRACT TRUNCATED AT 400 WORDS)

Ergonomics↗
PubMed1998

Myo-electric behavior of the trunk muscles during static load holding in healthy subjects and low back pain patients.

OBJECTIVE: The purposes of this study were to examine coactivational activities of four trunk muscles in various static holding tasks, and to examine the differences of muscle activation patterns between normal subjects and low back pain (LBP) patients. DESIGN: We used an one-way analysis of variance (anova) with repeated measures to analyze the effect of the knee angles, trunk flexion angles, and loading conditions on the amount of EMG activity. BACKGROUND: Epidemiologic studies attribute a considerable proportion of the incidence of LBP to lifting-related injuries. The relationship between LBP and trunk muscles integrated electromyography (IEMG) is controversial. METHODS: Forty volunteer subjects with no experience of LBP and 47 LBP patients recruited from Chung-Gung Memory Hospital participated in this experiment. Surface IEMG signals of four right and left trunk muscles (rectus abdominis, external oblique, erector spinae, and latissimus dorsi) were obtained in static holding tasks. RESULTS: In knee flexion, LBP patients had significant IEMG pattern change than normal subjects. In trunk flexion and loading conditions, normal subjects had significant IEMG pattern change than LBP patients. CONCLUSIONS: Trunk muscle groups have different muscle coactivation patterns in functional posture of load holding. Using surface EMG can discriminate LBP patients from normal subjects.

Journal Article↗
PubMed1984

Atrophy of sacrospinal muscle groups in patients with chronic, diffusely radiating lumbar back pain.

After surgery necessitated by lumbar back pain syndromes, radiolucency verified by CT may appear in the sacrospinal muscle group on the operated side. This radiolucency represents muscular atrophy and is in its most severe form a result of the replacement of muscle tissue with adipose tissue. Such muscular atrophy appeared in the present series in 31 out of all 156 patients (19.9%) and in 29 out of 94 patients operated on because of radiating lumbar back pain (30.9%). The radiological appearance, extent, and HU values of this muscular atrophy are presented in detail. Only weak correlations with the multitude of clinical symptoms and signs were found in this retrospective study. The effects of irreversible muscular atrophy on the indications for surgery and physiotherapy are discussed.

Adipose Tissue↗
PubMed1975

The sitting posture: an electromyographic and discometric study.

The disc pressure of the third lumbar disc and the myoelectric activity of several muscles of the back were measured. Three standing and nine unsupported sitting positions were studied as well as eight support parameters and six sedentary tasks. 1. Myoelectric activity is about the same in standing and in relaxed unsupported sitting. In the unsupported sitting positions the highest level of activity is found in anterior sitting and the lowest in posterior sitting. In the muscles of the cervical and lumbar regions the activity is always lower than in the muscles of the thoracic region. The disc pressure is considerably higher in unsupported sitting than in standing. In the unsupported sitting positions the highest disc pressure is found in anterior sitting and the lowest in sitting straight. 2. Both the myoelectric activity and the disc pressure decrease when the back is supported. Of the support parameters, the backrest inclination is the most important, myoelectric activity and disc pressure both decreasing with an increase in inclination. The disc pressure is considerably reduced also when the lumbar support is increased and when armrests are used. 3. Myoelectric activity and disc pressure are both comparatively low in writing, higher in typing, and still higher in lifting. In the car driver's seat the disc pressure increases both when the gear is shifted and when the clutch pedal is depressed. When the gear is shifted, there is also an increase in myoelectric activity.

Adult↗
PubMed1996

The effects of an RNA synthesis inhibitor on the survival and regeneration of rat motoneurones injured at birth.

This preliminary study aimed to test the proposal that neuronal death is triggered by expression of specific genes. In rat pups, the sciatic nerve was injured unilaterally on the first day after birth and actinomycin D, an RNA synthesis inhibitor, was administered 3 days later in a lower and higher dose to rat pups just prior to onset of motoneurone death induced by the lesion. Four weeks later, sciatic motoneurones from operated and contralateral pools were counted and their size measured. Significantly fewer motoneurones (16.7% +/- 2.9 SD) survived when the animals were treated with a lower dose of the inhibitor compared to saline treated controls (36.6% +/- 12.7 SD). Experiments recording tension generated in soleus muscle in response to sciatic nerve stimulation, at different ages following nerve crush, suggested that the treatment with the RNA synthesis inhibitor may have delayed regeneration of motor axons back to the muscle. However, survival of motoneurones after treatment with the higher dose did not differ significantly from controls (27.5% +/- 1.3 SD). Nevertheless, the higher dose significantly reduced growth of motoneurones after 4 weeks. Therefore, the higher dose, although impeding normal development of motoneurones, is less neurotoxic than a lower dose. This suggests that a balancing of conflicting effects may have occurred. The neurodegenerative effects of delayed reinnervation induced by RNA synthesis inhibition may be balanced by some neuroprotective effects at a higher dose. More extensive studies are required to validate these pilot findings.

Animals↗
PubMed1997

Changes in stature following plyometric drop-jump and pendulum exercises.

The aim of this study was to compare the changes in stature following the performance of plyometric exercises using drop-jumps and a pendulum swing. Eight male participants aged 21.7 +/- 1.8 years with experience of plyometric training gave their informed consent to act as participants. Participants undertook two exercise regimens and a 15-min standing test in a random order. The exercises entailed the performance of 50 drop-jumps from a height of 0.28 m or 50 pendulum rebounds. Participants were instructed to perform maximal jumps or rebounds using a 'bounce' style. Measurements of stature were performed after a 20-min period of standing (pre-exercise), 2-min after exercise (post-exercise) and after a 20-min standing recovery (recovery). Back pain and muscle soreness were assessed using an analogue-visual scale, at each of the above times and also 24 and 36 h after the test. Peak torque during isokinetic knee extension at 1.04 rads-1 was measured immediately before and after the exercise bouts, to assess the degree of muscular fatigue. Ground/wall reaction force data were recorded using a Kistler force platform mounted in the floor for drop-jumps and vertically on the rebound wall for pendulum exercises. Drop-jumps resulted in the greatest (p < 0.05) change in stature (-2.71 +/- 0.8 mm), compared to pendulum exercises (-1.77 +/- 0.7 mm) and standing (-0.39 +/- 0.2 mm). Both exercise regimens resulted in a significant (p < 0.01) decrease in stature when compared to the standing condition. Drop-jumps resulted in significantly greater peak impact forces (p < 0.05) than pendulum exercises (drop-jumps = 3.2 +/- 0.5 x body weight, pendulum = 2.6 +/- 0.5 x body weight). The two exercise conditions both invoked a small degree of muscle soreness but there were no significant differences between conditions. Both exercise regimens resulted in a non-significant decrease in peak torque indicating a similar degree of muscular fatigue. Based on the lower shrinkage resulted and lower peak forces, it can be concluded that pendulum exercises pose a lower injury potential to the lower back than drop-jumps performed from a height of 28 cm.

Adult↗
PubMed1986

Are there compartment syndromes in some patients with idiopathic back pain?

Palpable rigidity of the epaxial (paraspinal) muscles, lordotic flattening, and spinal flexion accompanying back pain generally are ascribed to epaxial muscle spasm. However, palpable rigidity without muscle spasm occurs in compartment syndromes and epaxial muscle contractions extend the spine, increasing lordosis. Epaxial compartment syndromes are proposed as a possible cause of palpable rigidity, lordotic flattening, and spinal flexion accompanying idiopathic back pain. This article demonstrates the following: existence of an epaxial compartment by latex and dye injections; simulation of epaxial compartment syndromes in unembalmed cadavers by saline injections; and a "Bourdon tube effect" producing spinal flexion with lordotic flattening during epaxial compartment syndrome simulation in embalmed cadavers. In addition, resting and exercising epaxial compartment pressures were measured in 18 normal volunteers with a slit catheter.

Aged↗
PubMed1992

[Stilling Duane syndrome and MRI: 2 preliminary results].

Dynamic mode magnetic resonance imaging (DMMRI) allows good visualization of the oculomotor muscles and allows their dimensions to be measured both when they contract and when they relax. The accuracy of this method has been checked and the measurements of the cross section of medial and inferior recti and of superior obliques can be considered to be valid. Measurements of length are inaccurate and the other muscles are not perpendicular to the sectional planes generally used in MRI of the head. By means of a fixation scale situated in the tunnel of the machine, the maximum diameter of medial recti in their thickest part was evaluated in two girls affected by a Stilling Duane retraction syndrome of the left eye. Two direction of the gaze were explored: 25 degrees at the right, then 25 degrees at the left, these angles being obtained by the fixation of particular points of the tunnel scale. The measurements have been made on axial sections, then on coronal sections, both medio-orbital and apical. The first finding is that the diseased medial rectus is much bigger than the healthy one. When relaxed, its thickness is about the same as that of the contracted normal muscle. Coronal orbital cross sections clearly show recession of the belly of the diseased muscle towards the back of the orbit. When contracted it stays in the apical plane and when relaxed in the medio-orbital plane. Lastly the relaxation is much weaker for the pathological muscle than for the healthy one.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2002

The influence of fatigue on trunk muscle responses to sudden arm movements, a pilot study.

OBJECTIVE: To examine fatigue induced changes in trunk muscle latencies following trunk muscle fatigue. DESIGN: A repeated measures within subject design.Background. Trunk muscle responses to sudden movements is of interest in clinical biomechanics and motor control. METHODS: Electromyographic profiles were recorded from transversus abdominis (finewire), internal oblique, rectus abdominis and external oblique and longissimus at the level of the 3rd lumbar vertebrae bilaterally. Four asymptomatic subjects performed arm-raising task using a visual cue before and after an isometric fatiguing trunk extension task. RESULTS: Feed-forward responses were not detected in all muscles for every trial. In general, following fatigue trunk muscle onset latencies occur earlier (left, P=0.0016; right, P=0.0475). CONCLUSIONS: Trunk muscle fatigue alters anticipatory postural adjustments in normal subjects. It remains unclear if there is a pattern for specific muscles changes between individuals and if these are reflected in individuals with low back pain. RELEVANCE: Trunk muscle fatigue and altered trunk muscles latencies to movement perturbations have been associated with low back pain. These findings suggest that there may be a link between centrally mediated response to isometric muscle fatigue and anticipatory motor control strategies.

Abdominal Muscles↗