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Estimating the tendency of motor unit recruitment during steady-hold and rapid contractions using surface EMG and Turns-amplitude analysis.
Pan, Li-Ling; Yu, Chung-Huang; Tsai, Mei-Wun; Wei, Shun-Hwa; Chou, Li-Wei.
Afiliação
  • Pan LL; Department of Physical Therapy and Assistive Technology, National Yang-Ming University, No.155, Sec.2, Li-Nong Street, Taipei, 112, Taiwan.
  • Yu CH; Department of Physical Therapy and Assistive Technology, National Yang-Ming University, No.155, Sec.2, Li-Nong Street, Taipei, 112, Taiwan.
  • Tsai MW; Department of Physical Therapy and Assistive Technology, National Yang-Ming University, No.155, Sec.2, Li-Nong Street, Taipei, 112, Taiwan.
  • Wei SH; Department of Physical Therapy and Assistive Technology, National Yang-Ming University, No.155, Sec.2, Li-Nong Street, Taipei, 112, Taiwan.
  • Chou LW; Department of Physical Therapy and Assistive Technology, National Yang-Ming University, No.155, Sec.2, Li-Nong Street, Taipei, 112, Taiwan. lwchou@ym.edu.tw.
Eur J Appl Physiol ; 115(11): 2407-14, 2015 Nov.
Article em En | MEDLINE | ID: mdl-26202486
PURPOSE: The purpose of this study was to investigate changes in the interference pattern in surface electromyography (EMG), and its relationship with the tendency of motor unit (MU) recruitment during steady-hold and rapid muscle contractions. METHODS: Fifteen healthy adults (eight females and seven males, 22.6 ± 1.5 years old) performed steady-hold and rapid isometric contractions of the bicep brachii, adductor pollicis, and tibialis anterior muscles at various force levels. Surface EMG recordings were analyzed using Turns-Amplitude Analysis (TAA). RESULTS: During steady-hold contractions, the number of turns per second (T/s) increased exponentially with force during submaximal contractions, and plateaued after force levels of 66, 70 and 57 % MVC for the tibialis anterior, bicep brachii and adductor pollicis muscles, respectively. These force levels were proximate to the maximal recruitment threshold (MaxRT) reported previously. The slopes of the T/s-force relationships before the MaxRT were significantly greater than the slopes after the MaxRT for all three muscles tested. During rapid contraction, the slopes of the T/s-force relationships were significantly lower than the slopes of the steady-hold contraction at 20-40 % MVC in all three muscles, and for 40-60 % MVC in TA muscles. CONCLUSIONS: Our results suggested that the changes in the number of turns in surface EMG with respect to muscle force can be used to estimate the force levels at which the majority of the MUs to be recruited, and completion of MU recruitment was observed at lower force levels during rapid muscle contraction.
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Texto completo: 1 Base de dados: MEDLINE Assunto principal: Recrutamento Neurofisiológico / Músculo Esquelético / Contração Muscular Limite: Adult / Female / Humans / Male Idioma: En Ano de publicação: 2015 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Recrutamento Neurofisiológico / Músculo Esquelético / Contração Muscular Limite: Adult / Female / Humans / Male Idioma: En Ano de publicação: 2015 Tipo de documento: Article