FORCE AND FATIGUE IN HUMAN TYPE I MUSCLE FIBRES: A SURFACE EMG STUDY IN PATIENTS WITH CONGENITAL MYOPATHY AND TYPE I FIBRE PREDOMINANCE

SUMMARY An isometric ischaemic intermittent m. biceps brachii exercise test is performed by 4 patients suffering from congenital myopathies which are characterized by a 100% type I fibre predominance, and by 26 healthy volunteers. Thirty contractions per minute are made at an 80% of maximal voluntar...

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Bibliographic Details
Published in:Brain (London, England : 1878) England : 1878), 1991-10, Vol.114 (5), p.2123-2132
Main Authors: LINSSEN, W. H. J. P., STEGEMAN, D. F., JOOSTEN, E. M. G., MERKS, H. J. H., TER LAAK, H. J., BINKHORST, R. A., NOTERMANS, S. L. H.
Format: Article
Language:English
Subjects:
Adult
Arm
Electromyography
Exercise
Fatigue - physiopathology
Female
Humans
Ischemia - physiopathology
Male
Muscles - blood supply
Muscles - pathology
Muscles - physiopathology
Muscular Diseases - congenital
Muscular Diseases - pathology
Muscular Diseases - physiopathology
Space life sciences
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Summary:SUMMARY An isometric ischaemic intermittent m. biceps brachii exercise test is performed by 4 patients suffering from congenital myopathies which are characterized by a 100% type I fibre predominance, and by 26 healthy volunteers. Thirty contractions per minute are made at an 80% of maximal voluntary contraction level. It is found that type I muscle fibres have a fourfold lower force-generating capacity than type II muscle fibres. The EMG amplitude shows that more EMG voltage is needed per unit force in the patients with 100% type I fibres compared with controls. Under standardized fatiguing circumstances the power density frequency spectrum shows a weaker shift to lower frequencies in patients with 100% type I muscle fibres compared with controls. The muscle fibre conduction velocity (MFCV) of type I muscle fibres shows no decline during ischaemic exercise indicating an unimpaired muscle membrane excitability.
ISSN:0006-8950
1460-2156
DOI:10.1093/brain/114.5.2123