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At least 1,675 records · Page 93Linked to original sources
PubMed2000

Fatigue of abdominal and paraspinal muscles during sustained loading of the trunk in the coronal plane.

OBJECTIVE: To measure fatigue-related changes in the electromyographic signals of trunk muscles during lateral bend loading, and to determine the effects of load magnitude, gender, and contraction time on these changes. DESIGN: A factorial experimental design. SETTING: A research laboratory. PARTICIPANTS: Twenty-four healthy volunteers (12 men, 12 women; mean age +/- SD, 22.9 +/- 3.1 yrs). INTERVENTION: Subjects sustained lateral bend loads at 20%, 40%, and 60% of their maximal exertion. OUTCOME MEASURES: Median frequency and total power of the power spectrum of the electromyographic signals. RESULTS: Trunk muscles' median frequency signals decreased and their total power increased as contraction time increased. These changes became more pronounced as the magnitude of loading increased. Men and women showed a similar rate of median frequency decline, but the total power of signals in men was larger than that in women. All muscles showed signs of fatigue, except that at 20% of maximal exertion only thoracic erector spinae fatigued significantly. CONCLUSIONS: Endurance training of paraspinal and abdominal muscles may be useful in preventing low back pain associated with lateral bend loading. The risk of back pain is similar in both genders and is higher with larger load magnitude and longer contraction time.

Adult↗
PubMed1995

An Energetic Comparison of Symmetrical and Asymmetrical Human Gait.

This article contrasts the mechanical energy profiles of asymmetrical galloping with those of symmetrical running in adult humans. Seven female subjects were filmed while performing overground running and galloping at their preferred velocities. A previous study (Whitall & Caldwell, 1992) showed that kinematic differences between these gait modes included higher preferred velocity for running than galloping, with distinct differences in interlimb coordination but surprisingly similar intralimb patterns. Energetically, in the present study the whole body center of mass during galloping was found to behave much as it does in walking; kinetic and potential energy profiles were out of phase, as compared with running, which exhibited in-phase fluctuations of kinetic and potential energies. The primary reason for these center of mass differences was found in the energetics of the back leg of galloping, which demonstrated alterations in timing of its energy fluctuations and less energy generation than the front leg. Analysis of the power sources underlying the segmental energies during swing phase showed that the back leg's energy changes were accomplished mainly through reduced use of the hip muscles and less interlimb energy transfer. The back leg's energetics during swing also displayed a shift toward greater reliance on nonmuscular energy sources. A pattern of energy inflow during early swing and energy outflow during late swing was common to both running and galloping, although the galloping legs both demonstrated more abrupt transitions between these phases. The possibility is raised that the 67/33 interlimb phasing ratio used in galloping is selected to reduce mechanical energy variations of the total body center of mass. These data suggest that models of asymmetric gait in humans must account for more than merely phase alteration.

Journal Article↗
PubMed1993

Changes of intracellular [Ca2+] during refilling of sarcoplasmic reticulum in rat ventricular and vascular smooth muscle.

1. Intracellular calcium concentration ([Ca2+]i) was measured in single myocytes isolated from either the cardiac ventricle or the mesenteric artery of the rat. 2. In both cardiac and smooth muscle, the application of caffeine produced an increase of [Ca2+]i which spontaneously decayed back to resting levels. In vascular smooth muscle cells, removal of caffeine produced a transient fall of [Ca2+]i to below the resting level. [Ca2+]i then returned to control levels. A transient undershoot of [Ca2+]i on removal of caffeine was also sometimes seen in cardiac cells. When the undershoot was absent in cardiac cells it could be induced by elevating [Ca2+]o. 3. In vascular smooth muscle cells noradrenaline increased [Ca2+]i and an undershoot of [Ca2+]i could be produced by its removal. In cardiac cells a small undershoot could sometimes be seen following the systolic Ca2+ transient produced by electrical stimulation. 4. In both cardiac and vascular cells the time constant of decay of the caffeine response (tau caff) was less than that of the recovery from the undershoot (tau us). On average the ratio tau us:tau caff was about 5 in smooth muscle. In cardiac cells the recovery of the undershoot was also considerably slower than that of the caffeine response. 5. If caffeine was removed before the rise of [Ca2+]i had fully decayed spontaneously then the magnitude of the undershoot was reduced. 6. It is suggested that the undershoot of [Ca2+]i on removal of caffeine results from refilling of the SR decreasing [Ca2+]i. The data from vascular cells can be fitted by this model if the dissociation constant, Kd, of the surface membrane Ca2+ pump for [Ca2+]i is about 1 microM. 7. Using the model, it is concluded from the ratio of the time constants shown above that the caffeine releasable content of the sarcoplasmic reticulum constitutes about 80% of total cellular calcium in both cardiac and smooth muscle.

Animals↗
PubMed1987

Ryanodine and the calcium content of cardiac SR assessed by caffeine and rapid cooling contractures.

The ability of rabbit ventricular muscle sarcoplasmic reticulum (SR) to accumulate and retain Ca during Na-free perfusion was assessed using caffeine contractures and rapid cooling contractures (RCC). Muscles were exposed to a Na-free medium for 15 min, during which time a transient contracture developed and relaxed back to the resting tension level. Muscles were then either exposed to 20 mM caffeine or rapidly cooled to less than 5 degrees C, both of which produced large contractures. The magnitudes of those contractures are believed to be a relative index of SR Ca content. Reduction of extracellular [Ca] from 2 to 0.2 mM did not significantly alter the magnitude of either Na-free caffeine contractures or RCC. These are not the maximum contractures that can be obtained. The possibility that low extracellular [Ca] ([Ca]o) may increase passive Ca permeability is suggested in explanation of this effect. After equilibration with 100 nM ryanodine, both Na-free caffeine contractures and RCC are virtually eliminated. This suggests that even if the SR could accumulate Ca during the initial Na-free exposure in the presence of ryanodine, it could not retain that Ca in Na-free medium. It is proposed that the sarcolemmal Ca pump can extrude Ca from the cells at a rate sufficient to deplete the ryanodine-treated SR. When removal of Na was accompanied by increase of [K]o (to 12, 20, or 30 mM), the Na-free RCC were enhanced. Increasing [K]o during Na-free superfusion in the presence of ryanodine resulted in demonstrable RCC that were graded with [K] and completely suppressed by nifedipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗
PubMed2005

Isometric back extension endurance testing: reasons for test termination.

STUDY DESIGN: Cross-sectional study. OBJECTIVE: The self-reported reasons for terminating isometric back extension endurance testing and their associations with test performance and other factors were investigated to gain insight into determinants of test performance. BACKGROUND: Factors limiting isometric back extension endurance performance remain unclear. Better understanding the reasons for termination of isometric extension endurance testing could provide insights into what the test actually reflects. METHODS AND MEASURES: Lifetime work, leisure activities and back pain questionnaire data, isometric back extension endurance testing (holding time, as measured in seconds), and reasons for test termination were obtained for a population-based sample of 544 working-age men. RESULTS: The most common reason for test termination was fatigue (62.5%), followed by pain in various parts of the lower extremities (12.6%) and back (3.2%). A history of daily low back pain over the prior 12 months and greater pain intensity of the worst back pain episode over the same period were associated with a greater likelihood of termination due to back pain. In a regression analysis, longer holding time was associated with stopping due to fatigue rather than low back pain, with a trend of 19 seconds (95% confidence interval [CI], -2-40) longer holding time. After controlling for low back pain history, those previously involved in competitive sports were 2.6 times more likely to stop due to pain. Those with a competitive sport history had 14 seconds (95% CI, 5-23) greater holding time than those without such a history. CONCLUSIONS: Isometric back extension endurance testing is most commonly reported to be terminated due to muscle-related capacity as indicated by fatigue. Back pain is more likely to decrease performance time in men with a history of significant (frequent, intense) low back symptoms.

Adult↗
PubMed1975

[Effects of ascorbic acid deficiency on lactate dehydrogenase. Quantitative and isoenzymatic study].

Light, acute vitamin C deficiency or repletion had no uniform effect on lactiodeshydrogenase, each organ reaching specifically (skeletal muscle, heart, kidney, spleen, liver adrenals, testes). There was no correlation with the age of the animal except in the case of testicular lacticodeshydrogenase isoenzymes. Reduction of food intake caracteristic of the late state of scurvy had no effect on the distribution of isoenzymes which was also independent of quantitative variations of enzyme activity. Vitamin C repletion restored the normal distribution of isoenzymes in spleen and liver but not in skeletal muscle. In the last phase of acute vitamin C deficiency, lactiodeshydrogenase activity was generaly elevated (heart and skeletal muscle excepted). When ascorbic acid was given back lacticodeshydrogenase activity remained elevated in liver and spleen but was lowered in skeletal muscle.

Acute Disease↗
PubMed1982

Latissimus dorsi flap: current applications.

The latissimus dorsi muscle has provided a useful flap for studying and defining the principles of the myocutaneous method. Clinically, it has yielded a valuable myocutaneous unit, based on its various pedicles. It has also provided the microvascular surgeon with a versatile unit that supplies a large volume of tissue with a long vascular pedicle. Investigation of the vascularity of the latissimus dorsi unit has led to better understanding of the vascularity of the muscle, and has extended the range of application of the myocutaneous method.

Back↗
PubMed1987

Effect of lumbar posture on lifting.

Twenty laborers assumed specific lumbar spine postures and lifted a 157 N crate to three different hand heights to determine if lumbar spine flexion moments or trunk muscle activity were affected by the lifting postures. Lumbar flexion moments were lowest when the workers used the lordotic and straight back postures, while the average erector spinae muscle activity tended to be highest in the lordotic and straight back postures. The kypohotic posture regularly reduced the activity of the erector spinae to bursts of activity while lifting and caused more discomfort during the lifting tasks than any other posture. Therefore, the lumbar lordotic posture is recommended as the posture of choice while lifting, particularly when lifting from the floor level.

Adult↗
PubMed2006

Multifidus size and symmetry among chronic LBP and healthy asymptomatic subjects.

Previous studies have provided evidence of multifidus muscle atrophy in people with low back pain (LBP). In cases of acute LBP, these studies have shown that the pattern of atrophy is both vertebral level and side specific. For chronic LBP, there are conflicting reports about the extent and location of muscle atrophy. The purpose of this study was to compare chronic LBP patients and asymptomatic subjects on measures of multifidus size (cross-sectional area; CSA) and symmetry (proportional difference of relatively larger side to smaller side). Data were obtained from 40 asymptomatic subjects without a prior history of LBP (13 females, 27 males), and a retrospective audit was undertaken of records from 50 chronic low back pain patients (27 females, 23 males) presenting to a back pain clinic. Results of the analysis showed that chronic LBP patients had significantly smaller multifidus CSAs than asymptomatic subjects at the lowest two vertebral levels. Males were found to have significantly larger multifidus CSAs than females at all vertebral levels except L5, the most common symptomatic level as determined by manual examination. The greatest asymmetry between sides was seen at the L5 vertebral level in patients with unilateral pain presentations. The smaller multifidus CSA was ipsilateral to the reported side of pain in all cases. The results of this study support previous findings that the pattern of multifidus muscle atrophy in chronic LBP patients is localized rather than generalized. Furthermore, between side asymmetry may be seen in chronic LBP patients presenting with a unilateral pain distribution.

Back↗
PubMedDate not supplied

Anger management style and hostility among patients with chronic pain: effects on symptom-specific physiological reactivity during anger- and sadness-recall interviews.

OBJECTIVES: We examined whether anger-in, anger-out, and hostility predicted symptom-specific muscle tension reactivity during anger induction (but not sadness induction) among patients with chronic low back pain (CLBP). For patients with CLBP, relevant muscles are the lower paraspinals (LPs). Anger-in x hostility and anger-out x hostility interactions were tested to determine whether particularly reactive groups of patients could be identified with a multivariable profile approach. METHODS: Ninety-four patients with CLBP underwent anger recall (ARI) and sadness recall (SRI) interviews, whereas LP and trapezius electromyography and systolic blood pressure, diastolic blood pressure, and heart rate were recorded. They completed anger-in, anger-out, hostility, and trait anger measures. RESULTS: Hierarchical regressions were used to test anger-in x hostility and anger-out x hostility interactions for physiological changes during the ARI and SRI. A significant anger-in x hostility interaction was found for LP change during the ARI (but not SRI) such that high anger-in/high hostility patients evinced the greatest reactivity. Effects for trapezius reactivity were nonsignificant. Significant anger-in x hostility interactions were also found for systolic blood pressure and diastolic blood pressure changes during the ARI such that high anger-in/low hostility patients showed the smallest changes. The anger-out x hostility interaction for diastolic blood pressure change during ARI was also significant such that high anger-out/low hostility patients showed the smallest changes. All effects remained significant with trait anger controlled. CONCLUSIONS: A multivariable profile approach may help identify especially vulnerable patient groups. Patients with CLBP who tend to suppress anger and are cynically hostile may be more likely to experience high levels of muscle tension near the site of pain and injury during anger, but not during sadness, than other groups.

Adaptation, Psychological↗
PubMed2006

The "yo-yo" technique to prevent cerebrospinal fluid rhinorrhea after anterior clinoidectomy for proximal internal carotid artery aneurysms.

OBJECTIVE: Resection of the anterior clinoid process is important for the exposure of aneurysms on clinoidal and supraclinoidal segments of the internal carotid artery. Cerebrospinal fluid (CSF) rhinorrhea can complicate anterior clinoidectomy when the optic strut is pneumatized and its removal communicates the subarachnoid space with the sphenoid sinus. We present a technique for repairing this defect and preventing CSF rhinorrhea. METHODS: A suture is secured around a strip of temporalis muscle, which is then pushed through the opening in the optic strut completely into the sphenoid sinus. The ends of suture that trail the muscle are used to retract the muscle from the sphenoid sinus back into the optic strut. The suture is trimmed and the repair is covered with sealant or fibrin glue. RESULTS: During an 8-year period in which 127 patients with proximal internal carotid artery aneurysms that required anterior clinoidectomy were treated, pneumatized optic struts were encountered in 14 patients (11%). Four patients were treated with the "yo-yo" technique, none of whom experienced CSF rhinorrhea. Before using this technique, 10 patients were managed with standard packing techniques (wax, muscle, and gel foam) and four of these patients subsequently experienced CSF rhinorrhea (40%). In these four patients, all required reoperation with either craniotomy and packing with pericranium (one patient), Couldwell-Luc procedure (one patient), or endoscopic transnasal obliteration of the sphenoid sinus with fat (two patients). CONCLUSION: The "yo-yo" technique of tightly wedging a muscle plug into the optic strut proved to be simple, fast, and effective, preventing CSF rhinorrhea in all patients in whom it was applied. Although experience with this technique is limited, reversing the direction of packing and pulling muscle from the sphenoid sinus into the optic strut eliminated a complication that occurred in 40% of patients with standard packing techniques.

Carotid Artery, Internal↗
PubMed1985

[Features of the innervation of fascia and their microcirculatory bed in the rat].

By means of silver impregnation, methylene blue staining and using glyoxylic acid, the neural apparatus of the muscle fasciae in the shoulder girdle and back and their microcirculatory bed have been revealed in laboratory white rats. An uneven concentration of neuronal terminals makes the base of neurotissue interactions of the muscle fasciae of the shoulder girdle and the back of the rats. Only a small part of microvessels possesses neural elements. The fasciae and their microvessels are innervated both by sensitive and sympathetic neural fibers and their endings; they differ from each other morphologically and histochemically. The rat fasciae are useful objects for vital observations for behaviour both of the vascular nerves and the avascular areas.

Animals↗
PubMed2005

Functional aspects of cross-legged sitting with special attention to piriformis muscles and sacroiliac joints.

BACKGROUND: Transversely oriented pelvic muscles such as the internal abdominal oblique, transversus abdominis, piriformis and pelvic floor muscles may contribute to sacroiliac joint stability by pressing the sacrum between the hipbones. Surface electromyographic measurements showed that leg crossing lowers the activity of the internal oblique abdominal muscle significantly. This suggests that leg crossing is a substitute for abdominal muscle activity. No previous studies addressed piriformis muscle and related pelvic structures in cross-legged sitting. METHODS: Angles of pelvis and femur were measured in healthy subjects in standing, normal sitting and cross-legged sitting, and were used to simulate these postures on embalmed pelvises and measure piriformis muscle elongation. Deformations of pelvic ring and iliolumbar ligament caused by piriformis muscle force were measured on embalmed pelvises. FINDINGS: Cross-legged sitting resulted in a relative elongation of the piriformis muscle of 11.7% compared to normal sitting and even 21.4% compared to standing. Application of piriformis muscle force resulted in inward deformation of the pelvic ring and compression of the sacroiliac joints and the dorsal side of the pubic symphysis. INTERPRETATION: Cross-legged sitting is common. We believe that it contributes to sacroiliac joint stability. This study demonstrates the influence of the piriformis muscle on sacroiliac joint compression. The elongation of the piriformis muscle bilaterally by crossing the legs may be functional in the build-up of active or passive tension between sacrum and femur.

Abdominal Muscles↗
PubMed2005

Influence of static lumbar flexion on the trunk muscles' response to sudden arm movements.

BACKGROUND: Viscoelastic creep of lumbar ligaments (prolonged forward bend) has been shown to negatively influence the spine's muscular reflexive behaviour and spinal stability. No studies to date have investigated the influence of spinal viscoelastic creep on the feedforward response of the trunk muscles to sudden arm raises. METHODS: Surface myoelectric activity was collected from the transversus abdominis/internal oblique, the lower erector spinae and the deltoid muscle during sudden ballistic arm raising before and after 10 minutes of prolonged forward bend in 11 healthy participants free of low back injury. The timing of trunk muscle activity relative to the deltoid muscle was calculated for 5 trials before and 5 trials after the creep procedure. RESULTS: Viscoelastic creep had no influence on the feedforward response of the trunk muscles during sudden arm raises. A feedforward response of the trunk muscles was not seen in every study participant and during every trial. CONCLUSION: Passive trunk muscle fatigue does not appear to influence the timing of the stabilizing role of the investigated trunk muscles to sudden arm flexion.

Journal Article↗
PubMedDate not supplied

Sectional neuroanatomy of the lower limb II: leg and foot.

The authors have produced a pair of articles that can be used to rapidly identify back, hip, and lower limb muscles and their innervation(s). This article presents the motor and sensory innervation of the lower limb by color-coding structures to match their peripheral nerves. It provides a companion summary table that allows prediction of unique patterns of denervation from 12 lesions sites.

Back↗
PubMed1986

Collagen metabolism of mouse skeletal muscle during the repair of exercise injuries.

The activities of prolyl 4-hydroxylase and beta-glucuronidase, the concentration of hydroxyproline as well as reticulin and collagen type III, IV and V stainings were followed in skeletal muscle during a 20-day period after a 9-h treadmill running in untrained and trained male mice, aged 4-6 months. The prolonged 9-h running of untrained mice temporarily increased prolyl 4-hydroxylase activity 2, 5 and 10 days after exercise, more prominently in the red than in the white part of quadriceps femoris-muscle, and in analogical manner as beta-glucuronidase activity in tibialis anterior-muscle. Twenty days after exercise these enzymatic activities were back to the control level. The hydroxyproline content of red muscle was increased for 10 and that of white muscle for 20 days after the exertion. Training for 45 days did not affect hydroxyproline content and prolyl 4-hydroxylase activity was at the control level after the training. A 9-h exercise increased prolyl 4-hydroxylase activity much less in trained muscle than in the untrained muscle and did not affect muscle collagen content. Histological observations showed fiber necrosis 2 days and signs of fiber regeneration 5 days after the exertion in untrained mice. Twenty days afterwards the regeneration was nearly completed. Reticulin staining was increased in injured muscle areas 10-20 days after the exertion. In immunohistochemical staining, antibodies to all studied collagen types (type III, IV and V) showed increased staining 5-20 days after the exertion in the areas of muscle injuries and regeneration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Time course of regeneration of minced frog muscles estimated by the level of energetic substrates.

1. Gastrocnemius muscles of frogs have been excised, chopped and put back into the leg. 2. The weight of the implanted muscles increases until the 8th day after the operation and then decreases to 1/3 of that of the control by the 30th day. 3. The inulin space is twice as high in regenerating muscle as in the unoperated controls. 4. Adenosine nucleotides are in an enzymatic equilibrium set by the ratio creatine/phosphorylcreatine during regeneration of the muscle. 5. Glycolytic intermediates (hexose monophosphate, fructose-1,6-diphosphate, alpha-glycerophosphate and lactate) have been measured during the course of muscle regeneration up to the 30th day. The results suggest that the glycolysis of regenerating muscle is very active. 6. The total creatine (sum of creatine and phosphorylcreatine) is very low after the operation: 5% of that of the controls; it rises sharply after the 8th day, and reaches 30% of that of the control on the 30th day. 7. The amount of total creatine seems proportional to the progress of the muscle regeneration. It is suggested to use this substance as a biochemical reference for biochemical works on muscle regeneration.

Adenine Nucleotides↗
PubMed1993

Mapping of sensory responses to epidural stimulation of the intraspinal neural structures in man.

A database is presented of sensory responses to electrical stimulation of the dorsal neural structures at various spine levels in 106 subjects subjected to epidural spinal cord stimulation. All patients were implanted for chronic pain management and were able to perceive stimulation in the area of pain. All patients entered in this study were able to reliably report their stimulation pattern. Several patients were implanted with more than one electrode array. The electrode arrays were placed in the dorsal epidural space at levels between C-1 and L-1. The structures that were likely involved include the dorsal roots, dorsal root entry zone, dorsal horn, and dorsal columns. At the present time, exact characterization of the structure being stimulated is possible only in limited instances. Various body areas are presented with the correspondent spine levels where implanted electrodes generate paresthesias. Areas that are relatively easy targets for stimulation are the median aspect of the hand, the abdominal wall, the anterior aspect of the thigh, and the foot. Some areas are particularly difficult to cover with stimulation-induced paresthesias; these include the C-2 distribution, the neck, the low back, and the perineum.

Abdominal Muscles↗