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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this preliminary report was to identify physiological parameters related to functional improvement in industrial workers with occupational low back pain (LBP) undergoing an intensive rehabilitation program. Four able-bodied and four LBP industrial workers were evaluated before and after a 4-week rehabilitation program. Dynamic and static strength tests, namely sustained isometric contractions, were performed in conjunction with surface electromyographic (EMG) measurements. Significant pre-rehabilitation differences were found between the two groups. Measured forces changed significantly in LBP subjects immediately after rehabilitation. No significative changes were found in the control subjects after the rehabilitation program. After rehabilitation, the slope of decay of the median frequency of the EMG power spectrum at L4 level, during a 60-sec isometric submaximal (60% MVC) contraction, decreased significantly (p < 0.02) indicating a lower fatigue level.
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PMID:Functional correlates in the rehabilitation of occupational low back pain. 928 77

A surface electromyographic (EMG) procedure for classifying muscle impairments in persons with low back pain (LBP) is described. The procedure was studied using a device, the Back Analysis System (BAS), to acquire and process EMG signals from six bilateral muscle sites during sustained isometric contractions designed to progressively fatigue the lower back. Back muscle impairment was determined on the basis of the different ways in which the EMG median frequency parameters change as a function of contraction duration and muscle site. The article describes a series of studies that have been useful in developing an automated procedure for identifying back muscle impairment by comparing individual test results to a normative database. To date, the research results have produced multivariate discriminant functions that have identified two muscle impairment categories associated with deconditioning and imbalances secondary to LBP. We have found that the functions can distinguish individuals with and without LBP with an accuracy of approximately 90%. Other studies are described in which the technique is applied to monitoring changes in muscle performance capability that occur following rehabilitation for LBP. Many of our findings here are also compared to the results of independent studies by others using similar procedures. The need for further research and development of the technique to improve its clinical applicability is also described.
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PMID:Classification of back muscle impairment based on the surface electromyographic signal. 932 44

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.
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PMID:Development of new protocols and analysis procedures for the assessment of LBP by surface EMG techniques. 932 45

Trunk muscles are designed to fulfill their role of continuous activity throughout the day, but pain and inactivity alter muscles so that they fatigue in normal situations. Lack of endurance of the trunk muscles is an important factor in low back pain (LBP). This paper examines some methods to objectively test endurance of trunk flexor and extensor muscles in static and dynamic situations, and presents results of endurance testing in persons with chronic LBP compared to nonimpaired cohorts. Self perception of fitness affects some test results. Methods for increasing endurance are discussed along with benefits observed from training programs.
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PMID:Endurance of trunk muscles in persons with chronic low back pain: assessment, performance, training. 932 47

A knowledge of the alteration in the fibre type profile of paraspinal muscle associated with low back pain is essential for the design of successful rehabilitation programmes. In attempting to compare the muscles of patients with low back pain with those of controls, few previous studies have considered factors such as gender, age, and size of the subjects, each of which can potentially confound interpretation of the results. We obtained samples of lumbar paraspinal muscle during spinal surgery from 21 patients with low back pain and, using the percutaneous biopsy technique, from 21 control volunteers matched for gender, age, and body mass. The samples were subject to routine histochemical analysis to determine characteristics of muscle fibre type. Compared with controls, the muscle of the patients had a significantly higher proportion of type-IIB (fast-twitch glycolytic) fibres than type-I (slow oxidative) fibres. The mean size of a given fibre type did not differ between the patients and the controls. Consequently, the relative area of the muscle occupied by type-IIB fibres was higher and that by type-I fibres was lower in the patients. The patients had a greater number of muscle samples with more than 1% type-IIC fibres, and abnormalities that could be described as pathological were more marked in the patients than in the controls. In conclusion, the paraspinal muscles of patients who have low back pain display a more glycolytic (faster) profile; this can be expected to render them less resistant to fatigue.
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PMID:Fibre type characteristics of the lumbar paraspinal muscles in normal healthy subjects and in patients with low back pain. 949 14

A 52-year-old woman visited a physician on Oct. 17, 1995 because of dizziness, general fatigue and a slight fever. A Chest X-ray film showed micronodulous and infiltrative shadows in the bilateral upper lung fields. Liver dysfunction was also recognized. As dyspnea and hypoxemia progressed very rapidly, the patient was intubated and kept under mechanical ventilation. A diagnosis of miliary tuberculosis with adult respiratory distress syndrome (ARDS) was made based on the detection of acid-fast bacilli from sputum obtained from the endotracheal tube. She was admitted to our hospital on Oct. 24, 1995 receiving anti-tuberculous drugs combined with high-dose methylprednisolone. As disseminated intravascular coagulation (DIC) and acute pancreatitis also developed, gabexate mesilate was added to the preceding therapy. This combination therapy was effective and the patient gradually improved. Two months after the admission, aneurysms of the abdominal aorta and left renal artery were discovered. As the size of the aneurysms had been increasing along with abdominal and low back pain, the patient was transferred to an other hospital for surgical treatment. She underwent a successful operation for pseudoaneurysms, the etiology of which was tuberculosis according to pathological findings and detection of acid-fast bacilli from the resected specimens. This is the 10th case of tuberculous aneurysm of the aorta which was successfully operated on in Japan. ARDS, DIC and aneurysm occur rarely as complications of miliary tuberculosis, but they are life-threatening, and lead to a serious prognosis if untreated. Early diagnosis of miliary tuberculosis and tuberculous aneurysm is very important for a good outcome.
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PMID:[A successfully treated case of miliary tuberculosis with adult respiratory distress syndrome and tuberculous aneurysm of abdominal aorta]. 969 83

The purpose of this article is to provide an overview of research to develop surface electromyographic (EMG) measurements for classification of paraspinal muscle impairments in persons with low back pain (LBP). The process of developing laboratory and clinically based protocols is described. Results of studies to evaluate the reliability of these measurements and their relationships with impairments and function are discussed. Research efforts to incorporate EMG spectral measurements, such as the median frequency, into a classification system to identify different types of muscle impairments are documented. Discriminant functions have been calculated based on case-control studies to identify 2 kinds of LBP impairments from constant-force isometric tasks: (1) excessive fatigue due to muscle deconditioning and (2) inhibition of muscle activation secondary to pain or pain-related behaviors. New areas of investigation designed to improve the classification accuracy of such functions using procedures other than discriminant analysis are described. Work in progress to extend the application of the technique to tasks other than those involving just isometric contraction, including those involving repetitive trunk movement, is also described.
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PMID:Classification of paraspinal muscle impairments by surface electromyography. 971 Dec 9

The fatigue of the back muscles appears to be strongly implicated as a risk factor for acquisition of low back pain, which is one of the leading ills of our industrial society. Previously, researchers have successfully measured the level of muscular fatigue by using the Fourier transform to analyze the frequency content of the electromyogram (EMG). However, due to the requirement that the EMG signal be stationary, the Fourier transform is suitable only for the analysis of static muscle exertions in which the muscle is held at constant length and tension. Because the majority of industrial work tasks are not static in nature, new methods for quantifying fatigue during dynamic work are needed. The wavelet transform is a novel, although mathematically well developed, technique for analyzing non-stationary signals that has only recently been applied to the study of EMG. Consequently, the main objective of this project is to develop techniques, using the wavelet transform, for the quantification of back muscle fatigue during dynamic repetitive working conditions.
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PMID:Wavelet analysis of electromyography for back muscle fatigue detection during dynamic constant-torque exertions. 973 40

The investigators describe their multifaceted approach to the study of the relationship between whole body vibration and low back pain. The epidemiologic study was a two center study of drivers and sedentary workers in the United States and Sweden. The vibration exposure was measured in the vehicles. It was found that the career vibration exposure was related to low back, neck, and shoulder pain. However, disability was related to job satisfaction. In vivo experiments, using percutaneous pin mounted accelerometers have shown that the natural frequency is at 4.5 Hz. The frequency response is affected by posture, seating, and seat back inclination. The response appears to be determined largely by the rocking of the pelvis. Electromyographic studies have shown that muscle fatigue occurs under whole body vibration. After whole body vibration exposure the muscle response to a sudden load has greater latency. Vehicle driving may be a reason for low back pain or herniated nucleus pulposus. Prolonged seating exposure, coupled with the whole body vibration, should be reduced for those recovering from these problems. Vibration attenuating seats and correct ergonomic layout of the cabs may reduce the risks of recurrence.
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PMID:Kappa Delta Award. Low back pain and whole body vibration. 975 85

This review focuses on the role of the paraspinal muscles in relation to the development and existence of low back pain. It begins with a discussion of the deficits in paraspinal muscle strength and fatigue-resistance observed in low back pain patients and addresses the issue of 'cause or effect' with respect to muscle dysfunction and back pain. Our current knowledge regarding the 'normal' fibre type characteristics of the human erector spinae is then presented and the influence of these fibre type characteristics on the muscle's performance capacity is discussed. Alterations in the 'microanatomy' of the musculature in connection with low back pain, and the associated implications for the performance capacity of the patient, are then considered. Finally, a number of outstanding issues in relation to the clinical significance of back muscle dysfunction are identified, leading to the proposal of areas for future research.
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PMID:Fibre type characteristics and function of the human paraspinal muscles: normal values and changes in association with low back pain. 1059 49


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