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At least 1,657 records · Page 92Linked to original sources
PubMed2000

Isometric progressive resistive exercise for osteoporosis.

OBJECTIVE: To assess the effect of site-specific resistive isometric exercises on muscle strengthening of 10 muscle groups over 2 months. A second study measured bone alkaline phosphatase (ALP) as a marker of bone formation and bone resorption [urine deoxypyridinoline (D-Pyr) crosslinks] in a similar cohort. METHODS: Twenty postmenopausal Caucasian women aged 56 to 69 yrs (mean 61) on a stable or no medication regimen for the previous 6 months participated in the initial exercise cohort. Twenty-one women ages 52-69 (mean 62) participated in the second cohort. All women had osteopenia (DXA T less than -1.0) or osteoporosis (DXA T less than -2.5). An inflatable ball with attached nonelastic straps provided progressive resistance. Exercises consisted of a 5 s maximum contraction against progressively increasing resistance of the ball or nonelastic straps. Muscle strengthening was measured by a hand held dynamometer at 0, 4, and 8 weeks. Twenty women completed 8 weeks of the initial study and 21 women completed the second study. RESULTS: Muscles showing increased strength in the first cohort were neck extensors (p < 0.04), hand grips (p < 0.02), elbow flexors (p < 0.05), quadriceps (p < 0.04), trunk extensors (p > 0.05, not significant = NS). Elbow extensors were purposely not exercised (as a control) and showed no significant strength increase. In the second cohort, increased muscle strength was measured in the neck extensors (p < 0.001), trunk extensors (p < 0.001), and left quadriceps (p < 0.024); and bone ALP increased (p < 0.05), with no change detected in bone resorption (urine D-Pyr). CONCLUSION: Brief progressively resisted isometric exercises for 10 min daily are an adequate stimulus for muscle strengthening of the neck, back, upper and lower extremities, and are capable of enhancing bone formation measured by bone ALP.

Alkaline Phosphatase↗
PubMed1994

Intramuscular potential changes caused by the presence of the recording EMG needle electrode.

A comprehensive volume conductor study of single fiber needle EMG (SF EMG) has been made. The electrode shaft is described as a passive inhomogeneity in the volume conductor. The most important observation is a substantial increase in single fiber action potential (SFAP) amplitude (up to 70%) for muscle fibers observed from a short distance. For SFAPs from muscle fibers located on the back of the SF electrode a shadow effect occurs which can result in a maximal amplitude decrease of 50%. SFAP wave form changes were observed only in situations without practical consequences or beyond physical reality. The presence of the needle shaft causes an anisotropy-like behavior of the relation between leading-off point to muscle fiber distance. The observed amplification due to the presence of the needle cannula decreases faster in the direction parallel to the cannula than in the direction normal to it: due to the amplification of SFAPs from muscle fibers observed from a short distance, the maximal distance from which SFAPs are included in fiber density measurements (amplitude greater than 0.2 mV) is raised from 380 microns to 460 microns. Also, the consequences of the formation of an edematous layer around the needle cannula have been studied. It was shown that the effect of high conductive fluid around the needle electrode can counteract the effects caused by the presence of the electrical double layer.

Action Potentials↗
PubMed1999

[Medical training therapy in lumbar syndromes].

Chronic low back pain can be considered to be one of the most frequently treated and most costly diseases in modern industrial societies. Dysfunctions and imbalances of the spine-supporting muscles increase the risk of low back pain. Consequently preventive treatment and rehabilitation have to aim at preserving and restoring the full capacity of the spine-supporting muscles as well as training coordination and spine-friendly behaviour. In addition to various measures of pain therapy, physiotherapeutic treatment including neuro-physiotherapy, physical treatment (eg electrotherapy), balneotherapy and supportive behavioural training, medical rehabilitation therapy (MRT) ranks among the most effective ways of treating low back pain. MRT applies guidelines and methods of exercise methodology within medically indicated programmes of preventive treatment and rehabilitation. Various objectives of MRT are outlined with special regard to the stages of MRT treatment, emphasizing positive adaptation of the neuro-muscular system in the course of rehabilitation. Physicians are responsible for MRT diagnosis and control. Taking into account the base disorder and the progress of therapy physiotherapists and the physicians in charge determine MRT objectives and treatment strategies.

Adaptation, Physiological↗
PubMed1998

Assessment of spinal musculature using surface electromyographic spectral color mapping.

STUDY DESIGN: A technique is described for analyzing electromyogram data from lumbar spinal muscles, with special reference to discrimination of people with back pain. The ability to discriminate was evaluated in 99 people (61 healthy and 38 with chronic or acute back pain), and the influence of load was assessed. OBJECTIVES: To evaluate methods of analysis of complex electromyogram data and to assess correlation of electromyogram information with clinical condition in people with and without back pain. SUMMARY OF BACKGROUND INFORMATION: In previous analyses of electromyogram data, only a small part of the data have been used. Spinal muscular decompensation has been postulated in chronic low back pain, but there has been no direct demonstration of this phenomenon. Objective measures are still elusive. METHODS: Lumbar spinal surface electromyograms were recorded during an isometric lifting task. The data were represented graphically as color-coded plots of electromyogram frequency, time, and electromyogram amplitude. Spectral width at half-peak amplitude (spectral half width) was calculated from the digitized, summed data. Ninety-nine people were tested: 48 men (29 with no recent [in the past 2 years] history of back pain, 16 with chronic back pain, 3 with acute back pain) and 51 women (32 with no recent back pain and 19 with chronic back pain). RESULTS: Spectral color maps in people with chronic back pain were markedly different from those in healthy people. Spectral half width was greater in people with chronic back pain than in healthy people (P < 0.01). Blinded analysis of spectral color maps allowed discrimination of people with back pain from healthy people with a sensitivity of 76% and a specificity of 81%. People with a history of back pain had markedly variable half widths. CONCLUSIONS: A new method of analysis of electromyogram data from lumbar spinal muscles has allowed discrimination between people with back pain and healthy people. This provides direct evidence of a correlation between muscular electrical function, measured by electromyogram, and low back pain. This technique may have potential as an objective measurement tool.

Adolescent↗
PubMed2000

Polychlorinated biphenyls in diseased lesser black-backed gull (Larus fuscus fuscus) chicks from the Gulf of Finland.

Diseases due to the degeneration of the liver and various other internal organs were the major cause of the exceedingly high chick mortality in lesser black-backed gulls (Larus fuscus fuscus) in the central Gulf of Finland, Baltic Sea, during 1991-1993. The same symptoms were found in chicks of common gulls (Larus canus) and herring gulls (Larus argentatus) from the same focal area, although at a much lower frequency. We found disproportionately high concentrations of polychlorinated biphenyls (PCBs) in liver relative to leg muscle in lesser black-backed chicks compared with common gull and herring gull chicks. The causality between PCB residues and chick diseases remains unknown. No signs of chick edema disease or abnormal frequency of embryonic deaths, commonly associated with organochlorines in biota, were found. It is concluded that studies made in a very small geographical area may not give a good correlation between dose and effect due to an even greater variation in tolerance. Another explanation is that the diseases may not have been PCB-induced.

Journal Article↗
PubMed2006

Paraspinal muscle spindle responses to the duration of a spinal manipulation under force control.

OBJECTIVE: More than 90% of chiropractic patients receive high-velocity, low-amplitude spinal manipulation (HVLA-SM) as part of their chiropractic care. The purpose of the current study was determine how the duration of a lumbar HVLA-SM given under force control affects the discharge of paraspinal muscle spindle afferents. METHODS: Experiments were performed on deeply anesthetized adult cats treated in accordance with the Guiding Principles in the Care and Use of Animals approved by the American Physiological Society. Muscle spindle afferents were identified in the dorsal roots. Neural activity was recorded from individual spindles located in the low back predominately from multifidus and longissimus muscles. Spinal manipulative loads were applied to the L6 vertebra. Force-time profiles were half-sine waves with impulse durations of 25, 50, 100, 200, 400, and 800 milliseconds, delivered at constant magnitudes of 33%, 66%, or 100% body weight. The relationships between spinal manipulation duration and muscle spindle responses were determined using a randomized block design. RESULTS: Mean instantaneous discharge frequency increased with decreasing impulse duration. There appeared to be a threshold effect for impulse duration below which the increase in muscle spindle discharge changed greatly with decreasing impulse duration and above which the discharge did not substantially change with decreasing impulse duration. This threshold was in the vicinity of the duration of an HVLA-SM applied clinically (<or=200 milliseconds). After the manipulation, muscle spindle afferents often became silent, but manipulation duration had little effect on this duration and also had little effect on the time it took for the afferents to recover their initial resting discharge. CONCLUSIONS: The findings suggest that one biomechanical characteristic of an HVLA-SM is its capacity to load paraspinal muscle spindles at a rate where their velocity sensitivity predominates over their length sensitivity.

Animals↗
PubMed2004

Optimizing segmental movement in the jumping header in soccer.

This study looks at segmental movements in the jumping header from an optimization viewpoint. Investigations on the header so far have focused on head restriction in the movement but have not clarified how and to what extent body segments influence the performance of the skill. In the present study a biomechanical model was used to analyze the jumping header in simulated competition to give a clear picture of an optimized header. Skilled soccer players headed balls at speeds of 13 m x s(-1) the results indicated that the head moves as a free non-restricted segment in the jumping header and should be allowed to do so, even though much soccer literature says otherwise to prevent injuries. The arm movement showed individual characteristics and gave no general advantages in optimizing ball speed after impact in the header The movement of the legs was, on the other hand, the single most important factor in the skill. Therefore, coaches and players shouldfocus on developing muscle strength in the stomach, back and pelvis and should put no restrictions on head and arm movement to optimize the jumping header.

Adult↗
PubMed2001

Vascular resistance in human muscle flaps.

Important differences in free muscle flap survival have been reported in the setting of long arterial and venous vein grafts. The authors provide insight into the etiology of flap failure by addressing the following question: Do differences in flap type result in clinically significant different vascular resistances and consequently anastomotic patency? A total of 15 human flaps were studied intraoperatively: 9 gracilis, 3 rectus abdominis, and 3 latissimus dorsi. The muscle was isolated on a single pedicle and hemodynamic stability was ensured. The venous pedicle was then divided. A timed collection of effluent was used to determine flow. Vascular resistance was calculated by dividing the change in pressure by the flow, and standardizing this for temperature and hematocrit. Average vascular resistance and standard deviation for the gracilis, rectus, and latissimus flaps was 10.34 +/- 7.77 mmHg per milliliter per minute, 2.79 +/- 1.50 mmHg per milliliter per minute, and 3.17 +/- 1.05 mmHg per milliliter per minute respectively. An inverse relationship between muscle vascular resistance and flap mass was found (p < 0.001). This indicates that larger muscles have less vascular resistance. The decreased resistance gives rise to higher flow rates and, as a result, potentially improved vein graft patency. The clinical implication is that a larger flap should be used when high flow-through is critical. The role of flap vascular territory makeup continues to be pursued.

Abdominal Muscles↗
PubMed2005

Lateral rectus muscle disinsertion and reattachment to the lateral orbital wall.

BACKGROUND/AIMS: Surgical correction of ocular alignment in patients with third cranial nerve paralysis is challenging, as the unopposed lateral rectus muscle often pulls the eye back to exotropia following surgery. The authors present a simple surgical approach to overcome this difficulty. This approach is also applicable to removal of unwanted overactivity of the lateral rectus in Duane syndrome. METHODS: A review was made of the records of four patients with third cranial nerve paralysis and one with Duane syndrome with exotropia in which the lateral rectus muscle was removed from its scleral insertion and reattached to the orbital wall. Additional surgery to bring the eye to the midline included medial rectus resection, medial transposition of the vertical recti, and passive suturing of the eye to the medial orbit wall. RESULTS: All patients achieved satisfactory ocular alignment following surgery. Ocular ductions were limited. These results were stable for 1.5-4 years of follow up. No major complications occurred. CONCLUSION: Lateral rectus muscle disinsertion and reattachment to the orbital wall to absorb its force and thus remove abduction torque was a simple and safe surgical procedure for restoring ocular alignment in four patients with third cranial nerve paralysis and in one patient with Duane syndrome with severe exotropia.

Adolescent↗
PubMed2005

Relationship between the thickness and hemodynamics of the erector spinae muscles in various lumbar curvatures.

BACKGROUND: There is little information about the relationship between the changes of hemodynamics and the morphologic changes of the erector spinae muscle. METHODS: Fifty healthy male volunteers participated. Ultrasonography was used to measure muscle thickness, and near-infrared spectroscopy was used to measure tissue blood volume and its oxygenation in the erector spinae muscle at L3 in six different relaxed trunk postures (flexed 20 degrees , flexed 40 degrees, flexed maximum, neutral posture, extended 20 degrees, and extended maximum of the lumbar spine). We also evaluated the reproducibility of the near-infrared spectroscopy measurements. FINDINGS: Near-infrared spectroscopy gave highly reproducible measurements. The thickness of the erector spinae muscle and the total and oxygenated hemoglobin were simultaneously increased during relaxed extension and decreased during relaxed flexion. Changes in the thickness of the erector spinae muscle with various lumbar curvature were similar in pattern to the changes in tissue blood volume and its oxygenation. INTERPRETATION: The erector spinae muscles' thickness, tissue blood volume, and its oxygenation are simultaneously increased during relaxed extension and decreased during relaxed flexion, as demonstrated by non-invasive near-infrared spectroscopy and ultrasonography. These findings might afford a better understanding of the pathomechanics of posture-related back symptoms. RELEVANCE: The erector spinae muscles' thickness, tissue blood volume, and its oxygenation are simultaneously increased during relaxed extension and decreased during relaxed flexion, as shown by non-invasive near-infrared spectroscopy and ultrasonography. Changes in hemodynamics and morphology of the erector spinae muscles in asymptomatic subjects are given for further research on the pathomechanism of back pain.

Adult↗
PubMed1979

Competitive interaction between foreign nerves innervating frog skeletal muscle.

1. Competition between two foreign nerves innervating frog skeletal muscle has been studied by using pairs of somatic motor nerves (s.m.n.s) or one s.m.n. and the preganglionic splanchnic nerve (s.p.n.) implanted into a denervated sartorius muscle that has been transplanted to the lymph sac of the back. 2. A single s.m.n. implanted into the muscle succeeded in innervating essentially every fibre within 2--3 months; tetanic stimulation of the nerve elicited 9--100% of the maximal direct tetanus tension. Most of the e.p.p.s were suprathreshold, since a single indirect stimulus evoked a twitch 60--100% as large as that to a direct stimulus. 3. If two s.m.n.s were implanted simultaneously, tetanic stimulation of either elicited 80--100% of the maximal tension to direct stimulation. If one nerve was implanted 2--3 months before the other, the second, although usually less effective than the first, normally innervated 50--100% of the fibres, with approximately the same time course of innervation as a single s.m.n. 4. Mutual synaptic repression was seen on examination of twitch tensions. With either simultaneous or staggered innervation, stimulation of each s.m.n. resulted in a twitch of 30--50% of the total direct twitch tension, with little overlap between the fields driven by the two nerves. Intracellular recordings showed that the distribution of subthreshold and spike-producing e.p.p.s reflected the existence of separate twitch fields. Even if one s.m.n. was implanted several months before the other and had time to establish suprathreshold junctions on most muscle fibres, an s.m.n. implanted later was able to reduce sharply the effectiveness of many junctions from the earlier nerve while itself innervating most muscle fibres. 5. The subthreshold e.p.p.s had low quantal content, typically ten or fewer quanta/e.p.p. The min e.p.p. frequency was very low, while min e.p.p. amplitude appeared to be normal. 6. In the vast majority of muscle fibres, junctions from the two nerves were not within recording distance of each other. Hence, we infer that the competitive interaction was mediated somehow via the muscle fibre. 7. The preganglionic splanchnic nerve, which also successfully reinnervated frog skeletal muscle, competed with a foreign s.m.n. in ways which differ qualitatively from the competition by a second s.m.n. In the presence of a s.m.n., synapses of the s.p.n. were almost universally subthreshold. However, if the s.p.n. was implanted 2--3 months before the s.m.n., the s.m.n. was prevented for several months from innervating fibres driven by the s.p.n. This delay in s.m.n. reinnervation was greater than if the first nerve implanted was also an s.m.n. 8. After 6--8 months of dual innervation by s.m.n. and s.p.n., the s.m.n. became almost totally dominant. However, if the s.m.n. was then sectioned, the s.p.n. became as effective, within approximately 1 week, as it would have been in the absence of the s.m.n.

Animals↗
PubMed1995

Motor patterns for horizontal and upside down walking and vertical climbing in the locust

The motor patterns of the locust's flexor tibiae and metathoracic subcoxal joint muscles were compared during unrestrained horizontal walking, vertical climbing and walking upside-down hanging from a branch. Combining anatomical and structural data with the results from myographic recordings revealed the role of these muscles during walking and their functional adjustments to different loads and gravity effects caused by changes in walking conditions. Motor patterns are remarkably constant during a given walking situation even at quite different walking speeds. In all walking situations, changes in step duration correlate strongly with changes in the duration of retraction but only weakly with the duration of protraction. Different motor units of one muscle can be distinguished by their spike amplitude. They may be active simultaneously or they may alternate and then fire in different phases of the step cycle. For example, during horizontal walking, the small unit of the first abductor (M125) is active during protraction and the large one during retraction. During retraction, the coxal muscles serve two functions: (1) the joint has to be brought back to the posterior extreme position by retractor muscles; (2) the joint has to be stabilized, that is held 'stiffly', by co-activity of functional antagonists. During protraction, it is moved to the anterior extreme position by powerful contractions of protractor muscles. The muscular activity patterns show marked differences depending on the walking situation. Some large motor units spike only sporadically during horizontal walking but burst during vertical climbing and upside-down walking (muscle M121p, the large units of muscles M126 and M120). During upside-down walking, muscles M120 and M121 and the large unit of muscle M125 are active during opposite phases of the step cycle when compared with horizontal walking and vertical climbing (for example, during walking and climbing, muscle M120 is active at the transition between retraction and protraction, whereas during upside-down walking, activity occurs during late protraction and early retraction). The results describe how motor patterns are adjusted to the different requirements of various walking situations.

Journal Article↗
PubMed1998

Augmentation of postural muscle tone induced by the stimulation of the descending fibers in the midline area of the cerebellar white matter in the acute decerebrate cat.

In a reflexively standing acute decerebrate cats, the cerebellar white matter was systematically stimulated and the effects on the level of postural muscle tone were studied. A stimulating microelectrode was placed systematically at 0.1-0.5 mm increments from H + 2 to H - 2 at levels ranging from P7.0 to P8.0 rostrocaudally and mediolaterally from LR0 to L1.5 or R1.5. Stimuli delivered to the restricted region of the cerebellar white matter along its midline resulted in simultaneous and bilateral augmentation of tonic activities in the neck, lumbar back, fore- and hindlimb extensor muscles along with increased levels in the forces exerted by each of the left and the right fore- and hindlimbs. Effective stimulus regions were located in the cerebellar white matter rostral and ventral to the most rostral part of the fastigial nucleus. Microinjection of a retrograde neural tracer, cholera-toxin b subunit conjugated horseradish peroxidase (CTb-HRP), into the lesioned effective stimulus sites resulted in a retrograde labeling of cells in the fastigial nuclei, bilaterally. All these results suggest that the augmentation of postural muscle tone was evoked by a selective activation of fastigiofugal fibers which course through the 'hook bundle'.

Animals↗
PubMed1993

Medical therapy of low back pain.

Low back pain is a common clinical symptom usually associated with mechanical disorders, primarily muscle strain, affecting the lumbosacral spine. The majority of patients with low back pain improve within a 2-month period with conservative medical management. Conservative management includes limited physical activity, injections, nonsteroidal anti-inflammatory drugs, and muscle relaxants. These therapies work best in combination and are very effective in decreasing low back pain.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

Does gynecologic surgery contribute to low back problems in later life? An analysis of the women's health and aging study.

OBJECTIVE: To examine whether women with potential injuries to the abdominal and pelvic musculature from past gynecologic surgery are at higher risk for low back pain (LBP). DESIGN: Cross-sectional population-based study. SETTING: Eastern region of the city and county of Baltimore, MD. PARTICIPANTS: Disabled women (N=1002) aged 65 and older, 448 of whom reported gynecologic surgery who were participants in the Women's Health and Aging Study. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: LBP presence in the last year, LBP severity for the last month, and adjudicated lumbar diagnoses (disk disease, stenosis) were examined in relation to reports of surgical menopause or ovarian surgery adjusted for LBP risk factors. RESULTS: Women with surgical menopause experienced more moderate LBP (adjusted odds ratio [AOR]=1.59; 95% confidence interval [CI], 1.1-2.3) than women without surgical menopause. Women with ovarian surgery also experienced more moderate LBP than women without ovarian surgery, but this association was not statistically significant (AOR=1.39; 95% CI, 0.96-2.09). Gynecologic surgery was not associated with an increased likelihood of lumbar disk disease or stenosis. CONCLUSIONS: Surgical menopause may increase the risk of moderate LBP. Further research is needed to determine how gynecologic surgery might influence low back pathology. Abdominal and pelvic muscle rehabilitation after gynecologic surgery may provide protection from LBP later in life.

Aged↗
PubMed1994

Asthma as an inflammatory disease.

Asthma has been described primarily as an inflammatory process only in the last 5 to 10 years. Previously, it was thought of primarily as a disease of nerves and smooth muscle. This inflammatory process is now considered to be an immunologically initiated, mediator-driven event. The observation that asthma is associated with an inflammatory process in the lungs has dramatically changed our understanding of the pathophysiology and treatment of this disease. Like many other theories that have undergone a significant change in direction, it is possible that over the next few years the pendulum will begin to swing back. The nerves and smooth muscles may (or may not) be implicated directly again. It is conceivable that in addition to an inflammatory process, underlying alterations in the architecture of the lungs will also be found. These alterations might serve to amplify the effects of inflammation, thereby leading to the clinical manifestations of asthma.

Asthma↗