PubMed · 14809834
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C D SHIELDS, J H KUITERT. 1951. Electromyography.. https://pubmed.ncbi.nlm.nih.gov/14809834/
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The main purpose of this study was to characterize brain activation patterns during a fatigue task involving repetitive maximal voluntary contractions (MVC) of finger flexor muscles. Fourteen young, healthy human participants performed approximately 100 handgrip MVCs (each 2-s contraction was followed by a 1-s rest) while their brain was imaged by functional MRI (fMRI). The handgrip force and electromyograms (EMG) of the finger flexors declined progressively to about 40% of the initial values at the end of the fatigue task, suggesting that significant muscle fatigue had occurred. In contrast, the level of the fMRI signal in the primary (sensorimotor), secondary (supplementary motor), and association (prefrontal and cingulate) motor-function cortices did not change significantly throughout the fatigue task (although the signal of the primary sensorimotor cortex showed a clear trend of decline). The fMRI data from the task of intermittent handgrip MVCs differed dramatically from those obtained in a 2-min sustained handgrip MVC published in a recent report, in which the overall fMRI-measured brain activation level was substantially lower and followed an increase-then-decrease pattern compared to the linear decreases in force and EMG. These results support the notion that the motor cortical centers control the tasks of repetitive and continuous muscle contractions differently and that there is a decoupling in the signal changes of the brain and muscles during muscle fatigue processes induced by maximal voluntary contractions.
BACKGROUND AND PURPOSE: To determine the frequency and severity of disorders of sleep and wake and their relation to the quality of life (QoL) in patients who have survived an episode of subarachnoid hemorrhage (SAH). METHODS: In a prospectively collected, consecutive series of 89 patients, 83 patients completed validated and frequently used questionnaires for the assessment of disorders of sleep and wake (SDL and Epworth Sleepiness Score) at least 1 year (range, 1 to 3.4 years) after the SAH. We used the modified Rankin scale for functional outcome and Short Form 36 (SF-36) to assess QoL. We related the occurrence of severe problems with sleep (insomnia or excessive daytime sleepiness score or both > or =3 on SDL) to functional outcome and to the QoL scores and compared the latter scores with data from a Dutch reference population. In a subset of 20 patients with severe problems with sleep, we performed polysomnographic and actigraphic studies at home during 48 hours. RESULTS: Twenty eight (34%) patients had severe problems with sleep. Frequently reported problems are initiating (25%) or maintaining (31%) sleep, difficulty returning (28%) asleep, tiredness (31%), and excessive sleepiness during the day (6%). QoL was considerably reduced in patients with severe problems with sleep. During the sleep monitoring studies, severe sleep fragmentation, sleep apnea, restless legs syndrome/periodic limb movement disorder, or a combination of these disorders of sleep and wake occurred in 19 of 20 patients. CONCLUSIONS: Many patients who have survived an episode of SAH have disorders of sleep and wake, which are related to the QoL.
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