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PubMed1992

[X-ray computed tomographic scans of lower limb and trunk muscles in facioscapulohumeral muscular dystrophy].

X-rays computed tomographic (CT) scans of muscles of the lower limbs and the trunk in 14 patients with facioscapulohumeral muscular dystrophy (FSH) were studied. The CT scans showed that the affected muscles were decreased in density and size. The laterality of muscular involvement was sometimes observed. The muscular lesions in the lower limbs showed proximal distribution. In the thigh, the hamstrings were affected first, the adductor muscles second, and then the muscular involvement progressed to the quadriceps femoris muscle. In the lower leg, the gastrocnemius and soleus muscles were relatively spared as compared with the tibialis anterior muscle. In the lumbar girdle, the abdominal muscles were involved first, the gluteal muscles second, the back muscles third, and the psoas major muscle were relatively spared. The muscular weakness of this distribution exacerbated lumbar lordosis. The neck muscles were less affected than those of the lumbar girdle. The CT scans in FSH demonstrated the characteristic pattern of muscular involvement, which differed from the inherited muscular diseases such as Duchenne muscular dystrophy, myotonic dystrophy, and others.

Adolescent↗

PubMed1982

[Localization of C. ovis in experimentally infected lambs].

Studied were the distribution of Cysticercus ovis in cadavers of lambs experimentally infected with various amounts of Taenia ovis ova, the ratio between superficially localized cysticerci and those found deep in the individual groups of muscles and organs, and the ratio between alive and dead cysticerci. The tests were carried out with thirteen lambs treated as follows: 2 animals were infected with 1000 T. ovis ova each; 3 were infected with 4000 ova each; 4--with 7000 ova each; and 4--with 30 000 ova each. No strictly defined predilection for the localization of Cysticercus ovis was established in the body of the experimentally infected lambs. In compliance with the parasite burden in the individual organs and muscle groups per unit of mass these ranked in the following descending order: heart, diaphragm, fore and hind limbs, masticatory muscles, neck and back muscles, tongue, and abdominal and intercostal muscles. Experimentally, highest was the percent of viable cysticerci in the muscles of the fore and hind limbs and in the muscles of the neck.

Animals↗

PubMed1993

Joint moments and muscle activity in the lower extremities and lower back in lifting and lowering tasks.

The mechanical loading on the body during the act of lifting has been estimated frequently. The opposite act of lowering has received much less attention. The aim of the present study was to compare the mechanical loading of the musculoskeletal system in lifting and lowering. Eight subjects repetitively lifted and lowered a load, using two different techniques (a leg and a back technique). The ankle, knee, hip and lumbosacral joint moments were estimated and the myoelectrical (EMG) activity of seven (leg and back) muscles was recorded. The differences between the lifting and lowering phase for the leg technique were similar to those observed when the back technique was applied. The joint moment curves in lifting showed a high level of agreement with the (time-reversed) moment curves in lowering. Peak moments in lowering were only slightly lower than in lifting (peak lumbar moments were 5.4% lower). These small differences were related to different acceleration profiles at the centre of gravity of the body/load complex. The EMG activity was considerably lower in lowering than in lifting. The mean EMG in lowering (average for seven muscles) was only about 69% of the EMG in lifting. This was attributed to the different types of muscle actions involved in lifting (mainly concentric) and lowering (mainly eccentric). Furthermore, the EMG results suggest that similar inter-muscular coordination is involved in lowering and lifting. The results give rise to the assumption that in lifting and lowering similar muscle forces are produced to meet the (nearly) equal joint moments, but in lowering these forces are distributed over a smaller cross-sectional area of active muscle, which might imply a higher risk of injury.

Acceleration↗

PubMed2003

Back extensor muscle endurance test scores in coal miners in Australia.

STUDY DESIGN: A cross-sectional analytic study was conducted. OBJECTIVES: To collect normative data on back extensor endurance holding times and evaluate the discriminative validity of the Biering-Sorensen test in a group of coal miners in Australia. SUMMARY OF BACKGROUND DATA: Low back pain is a common complaint among those working in the Australian coal mining industry. One test that may be predictive of first-time episodes of low back pain is the Biering-Sorensen test of back extensor endurance strength. While this test has been evaluated in overseas sedentary populations, normative data and the discriminative ability of the test have not been evaluated with coal miners. METHODS: Eighty-eight coal miners completed a questionnaire for known risk factors for low back pain, performed the Biering-Sorensen test, and undertook a test of aerobic fitness. Data analysis was performed to describe the groups and to determine whether any significant difference existed between those with a past history of low back pain and those without. RESULTS: Significantly lower than expected holding times were found in this group of coal miners (mean 113 s). This result was significantly lower than demonstrated in previous studies (mean 138 s, t87 = 6.32, p < 0.001). When holding times for those with a past history of low back pain were compared with times for those with no history of low back pain, the difference was not statistically significant (t86 = 1.56, p = 0.12), nor was there a significant difference in fitness between those with a past history of low back pain and those without (t86 = 0.47, p = 0.64). DISCUSSION/CONCLUSIONS: Coal miners in Australia have lower than normal Biering-Sorensen holding times. This lower back holding time does not differ between coal miners with a past history of low back pain and those without.

Adult↗

PubMed1997

Development of new protocols and analysis procedures for the assessment of LBP by surface EMG techniques.

Spectral parameters of the surface electromyographic (EMG) signal from lumbar back muscles assessed during a fatiguing isometric contraction can be used to classify different categories of low back pain (LBP) subjects and control subjects without LBP. In the test protocol currently used at the NeuroMuscular Research Center at Boston University, subjects contract their back muscles at 80% of their maximal voluntary contraction (MVC) force. This fatigue-based protocol has been successfully applied to persons with subacute or chronic LBP; those in acute pain, however, have not been included because of their inability to perform a maximal exertion. In this paper we will examine the force sensitivity of the currently used EMG parameters and also give an overview of some of our efforts to develop new test procedures. Our goal is to develop force-insensitive surface EMG parameters that can be used for classification purposes in populations of subjects who develop low trunk extension forces. In addition, the development of a model to predict MVC from anthropometrical measurements will be presented.

Adult↗

PubMed2003

The effect of comprehensive group training on cross-sectional area, density, and strength of paraspinal muscles in patients sick-listed for subacute low back pain.

The effect of exercise on back muscle cross-sectional area (CSA), density, and strength was evaluated in patients sick-listed for subacute low back pain. Twenty-four patients were randomized into an exercise (n = 11) or a control (n = 13) group. Patients in the exercise group followed a biweekly exercise protocol for 15 weeks. Control patients received usual care. Muscle CSA and density were measured by computed tomography before and after intervention. Isokinetic test of back extensors was conducted simultaneously. Results showed a tendency to increased muscle CSA and density in patients in the exercise group, a significant decrease in muscle CSA at L4-L5 in control group patients, and a significant difference in change between groups in muscle CSA at L4-L5. Back extension strength increased in patients in the exercise group, but the improvement was not significant compared with control group patients. In conclusion, there was a tendency for reversal of muscle atrophy after exercise.

Adult↗

PubMed2006

Effect of a stiff lifting belt on spine compression during lifting.

STUDY DESIGN: An in vivo study on weightlifters. OBJECTIVES: To determine if and how a stiff back belt affects spinal compression forces in weightlifting. SUMMARY OF BACKGROUND DATA: In weightlifting, a back belt has been reported to enhance intraabdominal pressure (IAP) and to reduce back muscle EMG and spinal compression forces. METHODS: Nine experienced weightlifters lifted barbells up to 75% body weight while inhaling and wearing a belt, inhaling and not wearing a belt, and exhaling and wearing a belt. IAP, trunk muscle EMG, ground reaction forces, and kinematics were measured. An EMG-assisted trunk model, including IAP effects, was used to calculate spinal compression and shear forces and to reveal the contribution of back muscles, abdominal muscles, and IAP to moment generation. RESULTS: The belt reduced compression forces by about 10%, but only when inhaling before lifting. The moment generated by IAP increased when wearing a belt and inhaling, but this moment was small and the increase was largely negated by the flexing moment generated by abdominal muscles. CONCLUSIONS: Wearing a tight and stiff back belt while inhaling before lifting reduces spine loading. This is caused by a moment generated by the belt rather than by the IAP.

Abdominal Muscles↗

PubMed2000

Tissue responses to natural aragonite (Margaritifera shell) implants in vivo.

The purpose of this study was to access tissue reactions to the outer prismatic (prism) and the inner nacreous (nacre) layers of the fresh water Margaritifera shell. The materials, in granule form, were implanted into the back muscles and femurs of rats for 1, 2, 4, 8 and 16 weeks. In the back muscles, a foreign body reaction was observed around the implants, starting from one week after implantation and reaching maximal proportions at two weeks. After four weeks, a thin layer of fibrous tissue encapsulated the implanted particles. The external surface of the material stained strongly with acid fuchsin, indicating degradation of implant. At femoral sites, newly formed bone was directly applied to the implant surfaces. The outer-most parts of the organic sheets in prisms were not degraded until 16 weeks after implantation and were embedded in the newly formed bone. The interface between bone and the implants showed close fusion by scanning electron microscopy (SEM). Energy dispersive X-ray analysis (EDAX) demonstrated a phosphorous-rich zone in the interface between bone and the implants, and no electron-dense layer in the interface was found by transmission electron microscopy (TEM). We conclude that Margaritifera shells are biocompatible, biodegradable and osteoconductive materials. Bonding between this natural aragonite and bone seems to occur via a phosphorous-rich intermediate layer.

Animals↗

PubMed1986

Effects of sinusoidal whole-body vibration on the lumbar spine: the stress-strain relationship.

The aim of this experimental study was to estimate the strain in the lumbar spine due to whole-body vibration (WBV). Four male subjects were exposed to vertical sinusoidal WBV with frequencies ranging from 1 to 15 Hz at two intensities (I1 = 1.5 ms-2 rms; I2 = 3.0 ms-2 rms). The compressive forces acting on the disc L3-4 during the extreme values of acceleration were predicted on the basis of anthropometric data, EMG of back muscles and the acceleration of the upper trunk, using a simple biomechanical model. The estimated mechanical activity of back muscles was not able to protect the spine under many exposure conditions. The highest compressive forces were predicted for WBV with 7.5, 8 and 4.5 Hz. The results suggest the possibility of fatigue failures at the endplates of lumbar vertebrae after intense long-term exposure to WBV.

Adaptation, Physiological↗

PubMed1986

Biomechanics of the squat exercise using a modified center of mass bar.

The purpose of the study was to investigate the effects of load height on selected performance characteristics of a squat exercise. A lower center of mass bar was designed that allowed the integrity of the squat exercise to be maintained while possibly reducing the chances of injury. Five trials were performed with the center of mass of the bar was set at shoulder height (C1) and lowered 18% (C2) and 36% (C3) of the subject's height below the normal bar position using the inverted "U" bar. All trials were filmed as the subjects lifted on a force platform. A balloon catheter was inserted into the subject's recta to monitor intra-abdominal pressure (IAP). High correlations were found between IAP, joint moment, and force data. Many of the critical parameters occurred just after the lowest squat position. Significant differences (P less than 0.05) in trunk angle excursion and trunk angular velocity indicated a greater ease of hip extension for the center of mass bar conditions. No differences were observed between conditions for thigh and knee angles and joint moments indicating kinematic similarity for the lower extremity. IAP was always least for C2 and C3, while compression, shear, and back muscle forces did not differ. It was estimated that the greater IAP was responsible for relieving back muscle forces and compression by up to 15 and 21%, respectively, and increased stress with the weight at shoulder height stimulated a response for greater IAP to help alleviate the stresses on the spine.

Adult↗

PubMed1996

Asymmetry of erector spinae muscle activity in twisted postures and consistency of muscle activation patterns across subjects.

STUDY DESIGN: An experimental study involving a repeated measures design was performed. OBJECTIVES: To describe the muscle activation pattern in extending from a twisted posture; to evaluate interindividual variation of this pattern; and to study the effects of fatigue development. SUMMARY OF BACKGROUND DATA: Extending the trunk from a twisted posture is a risk factor for low back pain. METHODS: Twelve male subjects performed contractions at 20%, 40%, 60%, and 100% of maximum in a neutral position and 15 degrees, 30 degrees, and 45 degrees twisted posture. Surface electromyography of six bilateral back muscle tracts was recorded during these 5-second contractions and during sustained contractions at 0 degree and 30 degrees and 40% of maximum. RESULTS: The data show an asymmetry in muscle activation, increasing with angle of twist. Activity was higher contralateral to the direction of twisting. Linear regression analysis with angle and torque level against electromyographic amplitude yielded a significant fit in 92% of the data sets. In 75% of the subjects, the regression lines were similar. The divergence of the activation pattern in the other subjects appears to be explained by a higher co-contraction level of abdominal muscles. Fatigue caused a shift in activity to the more laterally situated muscle tracts. CONCLUSIONS: Twisting causes an asymmetry in back muscle activation. Resulting stress concentrations in spinal motion segments, and a reduced spinal stability could underlie the observed relationship between the task investigated and low back pain. Fatigue may reduce further spinal stability. Some subjects display a divergent activation pattern, which probably involves higher spinal compression forces.

Adult↗

PubMed1984

The applied anatomy of the thoracolumbar fascia.

The thoracolumbar fascia was studied by dissection in ten adult human cadavers. The posterior layer of this fascia was found to consist of two laminae. The superficial lamina is formed by the aponeurosis of latissimus dorsi. The deep lamina consists of bands of fibers passing caudolaterally from the midline. Both laminae form a retinaculum over the back muscles, and the deep lamina constitutes a series of accessory posterior ligaments that anchor the L2 to L5 spinous processes to the ilium and resist flexion of the lumbar spine. The function of these ligaments is enhanced by the contraction of the back muscles and the action of certain, restricted portions of the abdominal muscles.

Adult↗

PubMed1997

Changes in serum creatine phosphokinase MM isoenzyme after lumbar spine surgery.

STUDY DESIGN: Serum concentrations of creatine phosphokinase and its isoenzyme were measured serially in 47 patients who underwent lumbar surgery. OBJECTIVE: To analyze the significance of postoperative creatine phosphokinase MM levels as indicators of muscle trauma after lumbar surgery. SUMMARY OF BACKGROUND DATA: The authors of the present study previously have reported on iatrogenic back muscle injury in an animal model and in man. However, the relationship between the change of the creatine phosphokinase MM isoenzyme level and muscle injury after surgery has not been clarified. METHODS: Peripheral venous blood samples were collected serially before surgery, just after surgery, and at 1, 3, 7, 14, and 21 days after surgery. The serum concentration of total creatine phosphokinase and its isoenzymes was measured by agarose gel electrophoresis. The serial postoperative change of the creatine phosphokinase MM isoenzyme concentration was evaluated with respect to age, gender, body weight, types and levels of surgery, and surgery time. RESULTS: Creatine phosphokinase MM activity increased after surgery and reached a maximum value 1 day after surgery, followed by recovery to the normal value 1 week after surgery. The maximum concentration of creatine phosphokinase MM isoenzyme in posterior lumbar surgery was significantly higher than that in anterior surgery (P = 0.04). It was significantly higher in men than in women (P = 0.02). Serum concentration of creatine phosphokinase MM isoenzyme showed no significant correlation to the extent of muscle exposure and surgery time. CONCLUSION: The time course of postoperative serum creatine phosphokinase MM isoenzyme activity is correlated with the histologic changes of the back muscles after surgery. The concentration of creatine phosphokinase MM isoenzyme in posterior lumbar surgery was significantly higher than that in anterior surgery. It was also significantly higher in men than in women.

Adolescent↗

PubMed1999

Eye position changes induced by neck muscle vibration in strabismic subjects.

BACKGROUND: In normal subjects vibratory stimulation of neck muscle proprioceptors can induce eye position change and visual illusory movement. The direction of apparent movement is vertical when the back muscles of the neck are stimulated and horizontal when lateral-rotation muscles are stimulated. The effect of muscle proprioceptor stimulation in individuals with defects in binocular vision, such as strabismus, has not been studied previously and is the subject of the present report. METHODS: In 23 strabismic patients with different levels of binocular vision, 70-Hz mechanical vibration was applied to three groups of neck muscles under both dark and normal light conditions, and eye position changes were recorded for each eye using an infrared reflection technique. The dominant eye fixated on a target while the non-dominant eye was covered. RESULTS: When the back muscles were stimulated, eye position changed in a downward direction, as previously demonstrated in the normal subjects. However, in strabismic subjects with poor binocular vision, stimulation of the horizontal rotation neck muscles resulted in eye position changes generally to the same side regardless of the muscle group activated. This differed from normal subjects, where the direction of the eye position changes is related to the group of muscles stimulated. The direction and amplitude of the eye position changes were the same under dark and light conditions. CONCLUSION: Proprioceptive information from neck muscles plays an important role in regulation of gaze direction. The difference that exists between normal subjects and strabismic patients is most likely related to differences in binocular function.

Adolescent↗

PubMed1993

Primary prevention of back symptoms and absence from work. A prospective randomized study among hospital employees.

The personnel at a geriatric hospital were randomized into two groups. One group was allowed to exercise during working hours to improve back muscle strength, endurance, and coordination. The other group did not participate in the exercise program and received no further advice or information. After 13 months, the training group had increased back muscle strength. One subject had been absent from work 28 days in the training group whereas 12 subjects had been absent 155 days from work because of low back pain in the control group (P < 0.004). The back pain complaints and intensity of back pain in the training group also decreased in a statistically significant way. Every hour spent by the physiotherapist on the training group reduced the work absence among the participants by 1.3 days, resulting in a cost/benefit ratio greater than 10.

Absenteeism↗

PubMed1993

[Experimental study on cryopreservation and intramuscular allografting of vertebral body and disc units].

This study investigated optimal conditions for preservation and intramuscular allografting of vertebral body and disc units. First, thirty-one vertebral body and disc units were removed from rabbits and divided into three groups: a slow freezing group, a quick freezing group, and a fresh non-freezing group. In the slow freezing group, disc units were slowly cryopreserved by decreasing temperatures from 4 to -80 degrees C using a program freezer. In the quick freezing group, they were rapidly cryopreserved by freezing to -80 degrees C without a program freezer. Second, to determine favorable duration of immersion in cryoprotectant (10% dimethyl sulfoxide), another 20 vertebral body and disc units were divided into four groups: immersed at 4 degrees C for 30, 90, 240 and 1440 minutes. After immersion, they were cryopreserved slowly using a program freezer. These disc units were thawed and examined histologically and biochemically. In the slow freezing group, both cell number in the anulus fibrosus and the value of 35SO4 incorporation in the disc were higher than those in the quick freezing group, and the disc viability of the 90-minute group was the highest. On the basis of these experiments, vertebral body and disc units were grafted into the back muscles of rabbits. To investigate the viability of the disc after allografting, another 38 specimens were grafted into the back muscles and examined after 4 or 12 weeks. The values for 35SO4 incorporation of each group at 4 weeks were about 80% of the pre-grafting level and those at 12 weeks were about 60%, and the viability of discs maintained. There were no significant differences between the slow freezing group, the quick freezing group, and the fresh non-freezing group after grafting. Further study is needed to determine a method in maintaining viability of the disc after grafting.

Animals↗

PubMedDate not supplied

The EMG development of the longissimus and multifidus muscles after plugging the horizontal semicircular canals.

The effects of plugging both horizontal semicircular canals at the 5th postnatal day (P5) on the development of the EMG of two back muscles (the M. longissimus lateralis and the M. multifidus) were studied in rats between P5 and P46. The EMG was related to locomotion, grooming, and rearing of these rats. Special attention was paid to locomotor behavior. After this vestibular deprivation, the development of a consistent temporal relation between burst activity in the EMG of both Mm. longissimii laterales and the swing phase of one hind paw was retarded by about 3 days. The development of coupling of maximal activity in the M. longissimus lateralis to the swing phase of one of the hind paws was even more retarded. No differences were observed between normal and vestibularly deprived rats during the development of activity in the Mm. multifidi. Our results indicate that information from the horizontal semicircular canals is essential for dynamic postural development and probably, therefore, for motor development in general. Furthermore, lack of such information has effects on the fine tuning of back muscle activity during locomotion at least until P40.

Animals↗

PubMed2001

Extensibility and stiffness of the hamstrings in patients with nonspecific low back pain.

OBJECTIVE: To investigate the extensibility and stiffness of the hamstrings in patients with nonspecific low back pain (LBP). DESIGN: An experimental design. SETTING: A university laboratory for human movement analysis in a department of rehabilitation medicine. PARTICIPANTS: Forty subjects, a patient group (20) and a healthy control group (20). INTERVENTIONS: Subjects laid supine on an examination table with a lift frame, with left leg placed in a sling at the ankle. Straight leg raising, pulling force, and activity of hamstring and back muscles were recorded with electrodes. Patients indicated when they experienced tension or pain. MAIN OUTCOME MEASURES: The lift force, leg excursion, pelvic-femoral angle, first sensation of pain, and the electromyogram of the hamstrings and back muscles measured in an experimental straight-leg raising set-up. RESULTS: The patient group showed a significant restriction in range of motion (ROM) and extensibility of the hamstrings compared with the control group. No significant difference in hamstring muscle stiffness can be assessed between both groups. CONCLUSION: The restricted ROM and the decreased extensibility of the hamstrings in patients with nonspecific LBP is not caused by increased muscle stiffness of the hamstrings, but determined by the stretch tolerance of the patients.

Adult↗