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Surface mechanomyogram reflects muscle fibres twitches summation.
Orizio, C; Liberati, D; Locatelli, C; De Grandis, D; Veicsteinas, A.
Afiliação
  • Orizio C; Department of Biomedical Sciences and Biotechnologies, University of Brescia, Italy.
J Biomech ; 29(4): 475-81, 1996 Apr.
Article em En | MEDLINE | ID: mdl-8964777
The aim of this work is to define the pattern of summation of the muscle fibre twitches in the surface mechanomyogram (MMG) generation process. For this purpose, two groups of muscle fibres of the extensor digitorum communis (EDC) were stimulated using needle electrodes. To these two artificial (because made by different muscle fibre types) motor units (MU1 and MU2), we administered: (a) separate stimulations: 3 and 9 Hz (MU1), 8 and 20 Hz (MU2) for 5 s; (b) simultaneous stimulation: 3 Hz (MU1) + 8 Hz (MU2); 9 Hz (MU1) + 20 Hz (MU2) for 5 s. The mechanomyograms, recorded during separate stimulation of MU1 and MU2, were linearly summated for the generation of a mechanomyographic signal to be compared with the one detected during (b) stimulation procedure. The bispectrum and the bicoherence of the generated MMG (MMGg) and of the MMG recorded during simultaneous (MMGs) stimulation were calculated for the detection of the quadratic non-linearity in the system responses. It was found that the MMGg and MMGs presented difference in the bispectrum and bicoherence index only when the 9-20 Hz stimulation pair was considered In conclusion, our data indicate that the MMG derives from the summation of the active muscle fibres twitches and that the latter is linear only for very low firing rates. This is to be carefully considered when studies on MMG modelling will be undertaken.
Assuntos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Fibras Musculares Esqueléticas / Eletrofisiologia / Contração Muscular / Músculos Limite: Humans Idioma: En Ano de publicação: 1996 Tipo de documento: Article
Buscar no Google
Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Fibras Musculares Esqueléticas / Eletrofisiologia / Contração Muscular / Músculos Limite: Humans Idioma: En Ano de publicação: 1996 Tipo de documento: Article