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

Human adductor pollicis was fatigued during circulatory occlusion by supramaximal stimulation via the ulnar nerve using intermittent trains of stimuli in ascending (1, 10, 20, 50 and 100 Hz) and descending (100, 50, 20, 10 and 1 Hz) frequencies to investigate the contribution of relaxation rate slowing and post-tetanic potentiation (PTP) to fatigue resistance. At 50 and 100 Hz force was initially well maintained despite a marked loss of excitation as indicated by EMG, demonstrating the operation of a high-frequency 'safety factor' which appeared independent of the pattern of stimulation. At 10 Hz, force was initially potentiated before declining during both activity series. Potentiation was greater during the descending frequency series and the rate of decline of force, or fatigability, was reduced. The 'extra' low-frequency potentiation at 10 Hz was not simply the result of PTP of twitch force, since this declined more during the descending than during the ascending series, nor the result of maximal relaxation rate changes which were identical for both fatiguing series. It is hypothesized that the extra potentiation and reduced fatigability at low stimulation frequencies, when preceded by high frequency, is the result of increased myofibrillar Ca2+ availability and/or sensitivity. These findings may have important practical implications in relation to functional electrical stimulation techniques as used in paraplegia and in other areas of muscle research where fatigue is to be minimized.
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PMID:Mechanisms resisting fatigue in isometrically contracting human skeletal muscle. 323 84

Acutely high level quadriplegics may experience neuromuscular respiratory insufficiency secondary to loss of use of intercostal and abdominal muscles as well as partial involvement of the phrenic nerve. Frequently, these patients will require mechanical ventilation in the initial stages of their treatment. These patients may present difficulty with weaning off the ventilator. In addition, poor respiratory reserve increases the risk of episodic decompensation. We have instituted a progressive resistive exercise protocol (PRE) analogous to PRE commonly used in training skeletal muscle, to wean patients off the ventilator. This involves determining the patient's endurance to the development of fatigue while off the ventilator. Patients are re-evaluated weekly until they are weaned from the ventilator. Three case studies are reported in which this protocol was used. In addition to our standard respiratory therapy and physical therapy protocols, values for vital capacity and maximum inspiratory force at admission and post-weaning were recorded. After completion of the programme, none of the patients required re-intubation or subsequent mechanical ventilation. This method of diaphragm training may be useful in weaning high level quadriplegics from the ventilator.
Paraplegia 1987 Apr
PMID:Progressive resistive exercise in weaning high quadriplegics from the ventilator. 358 8

This is a study of two children, aged respectively 10 and 6 years, who sustained a spinal cord injury at the C1 C2, causing apnoea. After the bilateral implantation of diaphragm pacemakers and periods of conditioning, they were able to adapt to continuous and simultaneous full-time ventilatory support of both diaphragms without any sign of fatigue, for more than 24 and 11 months, respectively.
Paraplegia 1986 Oct
PMID:Permanent artificial respiration by diaphragm pacemaker in tetraplegic children. 377 64

The purpose of the study was to discover the independent and combined effects of age and duration of injury on selected long term health outcomes of 83 spinal cord injured (SCI) men (age range 21-79 years; duration of spinal cord injury 3-52 years). Specifically, the study examined a multivariate model which specified that age, duration, the interaction of age and duration, and level of lesion were related to the following health outcomes: pain, fatigue, functional independence, mobility, illness and symptomatology, perceived overall health, social support, life satisfaction, and economic stability. Age had significant main effects on three outcomes. With increasing age, the sample experienced more fatigue, decreased activity (due to pain), and more overall satisfaction with their lives. Duration of SCI showed significant main effects on two outcomes. As subjects lived longer with their SCI, they felt less financially secure and experienced more symptoms and illnesses. Significant interaction effects of age and duration of SCI were found for two outcomes. Older age combined with longer duration of SCI amplified subjects' perceptions of financial insecurity, and threats to health. The findings send a clear message to service-providers and policy makers about the added vulnerability of older disabled individuals, about the need for extra vigilance in health care issues, and about the necessity of a social-economic safety net for already disadvantaged individuals.
Paraplegia 1995 Jul
PMID:The effect of aging and duration of disability on long term health outcomes following spinal cord injury. 747 24

In adult paraplegic subjects one tibialis anterior muscle received daily electrical stimulation for 4 weeks at twice motor threshold to determine changes of its contractile properties (this paper) and its morphological and histochemical profiles (following paper). Force, speed of contraction and fatigue resistance were assessed by percutaneous electrical stimulation of the muscle with torque measured about the ankle. Comparative contractile tests were performed on 51 normal adult subjects and new parameters for force measurement proposed, particularly where maximum voluntary contraction cannot be obtained. In paraplegic subjects before stimulation the tibialis anterior muscle showed evidence of disuse with decreased force, faster contraction and relaxation, and reduced fatigue resistance. The effects of two stimulus patterns were compared: 10 Hz, and 10 Hz with 100 Hz bursts. After stimulation contraction was slower, fatigue resistance increased and there was a tendency for force to increase. No differences occurred using the different stimulus patterns. Four weeks later fatigue resistance was partially maintained, while speed of contraction reverted to pre-stimulus levels.
Paraplegia 1995 Aug
PMID:Influence of electrical stimulation of the tibialis anterior muscle in paraplegic subjects. 1. Contractile properties. 747 37

Out of a regional traumatic spinal cord injury population consisting of 379 individuals, 353 (93.1%) participated in the present study. Subjects were individually interviewed using semi-structured protocols. In addition, previous medical records were available for over 96% of subjects, and were used in all these cases to minimise recall bias. Cause of injury, prevalence of present medical symptoms and occurrence of medical complications in the post-acute, post-discharge phase were recorded. Neurological classification was verified by physical examination according to ASIA/IMSOP standards. Many subjects had experienced complications since discharge from initial hospitalisation, especially urinary tract infections, decubitus ulcers, urolithiasis, and neurological deterioration. Prevalence of medical symptoms was also high. More than 41% of subjects with spastic paralysis reported excessive spasticity to be associated with additional functional impairment and/or pain. Almost two-thirds of subjects reported significant pain, with a predominance of neurogenic-type pain. Bladder and bowel dysfunction were each rated by nearly 41% of subjects as a moderate to severe life problem. As expected, sexual dysfunction was also commonly reported. Prevalence of reported symptoms by general systems review was high, particularly fatigue, constipation, ankle oedema, joint and muscle problems, and disturbed sleep. However, lack of adequate normative data precludes comparison with the general population. The frequent occurrence of reported medical problems and complications support advocacy of comprehensive, life-long care for SCI patients. The commonly reported problems of neurogenic pain and neurological deterioration, in particular, require more attention, as these symptoms are not seldom ominous, either by virtue of their impact on quality of life, or because of underlying pathology.
Paraplegia 1995 Jun
PMID:The Stockholm spinal cord injury study: 1. Medical problems in a regional SCI population. 764 55

Restoration of standing and of gait by functional electrical stimulation in clinically complete paraplegic patients was modified in the course of treatment and in the stimulation parameters. By substituting an initial cyclic muscle strengthening with an active stimulated standing, four patients with T3-11 lesions started walking with electrical stimulation in 10-17 days. They walked without ankle-foot orthoses. With a satisfactory stride length of 0.75-0.97 m, their gait velocity ranged from very slow to that of a leisurely healthy gait. Already established stimulation of the quadriceps muscles for standing and of the peroneal nerves for lower limb flexion during the swing phase of gait was applied. Diminished limb flexion after several weeks was restored by an increase of the stimulation frequency of the peroneal nerve from 20 to 60 Hz. EMG and kinesiological measurements displayed an improved direct response of the ankle as well as of the reflex mediated hip, knee and ankle flexion response. At the same time stimulation frequency was reduced to 16 Hz for the quadriceps muscles in order to reduce fatigue.
Paraplegia 1995 Mar
PMID:Restoration of gait by functional electrical stimulation in paraplegic patients: a modified programme of treatment. 778 13

Spasticity is a common problem following spinal cord injury. The drug of choice to control spasms is baclofen. There would appear to be no reported studies which have evaluated the psychological and emotional effect of this drug. This preliminary study investigated a number of such effects, including depression, anxiety and general mood state. First, we examined 10 subjects before and during the administration of baclofen. They were then compared to a control group of 12 subjects. A second cohort of 12 subjects taking baclofen were compared to a control group of nine subjects at a specific time after injury. Results indicated that whilst some significant differences were found, suggesting an increase in fatigue with use of baclofen, no major adverse psychological effects were noted. The implications of these results were discussed and suggestions for further research were highlighted.
Paraplegia 1994 May
PMID:Psychological and emotional effects of the use of oral baclofen: a preliminary study. 805 53

This study compared metabolic and cardiopulmonary responses to incremental supine and upright sitting arm crank ergometry (ACE) in nine men with spinal cord injured paraplegia ranging from T1-T5. Both tests consisted of continuous graded ACE from rest to volitional fatigue on a modified electronically braked cycle ergometer with the work rate increased by 8.2 W.min-1. No significant differences (P > 0.05) existed for peak ACE power output (W), oxygen uptake, pulmonary ventilation, respiratory exchange ratio, and O2 pulse between the two tests. Heart rate and O2 pulse responses at six submaximal work rates representing 0-58% peak W were also not significantly different between postures. These data indicate that ACE tolerance in persons with high-lesion paraplegia was not enhanced when ACE was performed in the supine posture.
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PMID:Influence of posture on arm exercise tolerance and physiologic responses in persons with spinal cord injured paraplegia. 814 38

The American Thoracic Society (ATS) has formulated guidelines for spirometry. We hypothesized that individuals with SCI (SCI), as a result of weak respiratory muscles, would exhibit poor test acceptability and reproducibility. Seventy-eight SCI subjects (39 with complete SCI) answered a respiratory questionnaire and performed spirometry. Of those with complete SCI, the proportion of subjects which met ATS criteria decreased with higher levels of injury. Poor test performance was not associated with age, respiratory symptoms or muscle fatigue. The most common reason for failing to meet ATS criteria for acceptability was excessive back extrapolated volumes (EBEV). Individuals with efforts that were acceptable except for EBEV and/or for exhalation of less than six seconds had values for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) that were reproducible. If ATS criteria for acceptable spirometry were used in studying subjects with SCI, individuals producing otherwise reproducible values for FVC and FEV1 would be excluded. We found reproducibility similar to what has been reported in other cohorts and conclude that longitudinal study of respiratory function in SCI is feasible.
J Am Paraplegia Soc 1993 Oct
PMID:Spirometry--acceptability and reproducibility in spinal cord injured subjects. 827 Sep 15


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