Motor units activity in EMG, MMG and force ripple: three pictures for one subject

• Autorzy: Orizio C. , Gobbo M. , De Grandis D. , Revenni R.
• Języki publikacji: EN

Abstrakty

EN

Mechanomyogram (MMG) detects the muscle surface oscillations due to the mechanical activity of the motor units (MU). Even during static contractions MMG presents macro components (due to the gross dimensional changes of the muscle-tendon unit from rest to activity) and micro components (the summation of the dimensional changes of the fi bres of each recruited motor unit). The single MU mechanical contribution to MMG (MUMC) was defi ned by Gordon and Holbourn a the ‘‘mechanical counterpart” of the MU action potential. During voluntary contraction MUMC and MU twitch (MUT) can be extracted from MMG and force ripple signal by means of the EMG driven spike triggered averaging technique. In small hand muscles during 5% of the maximal voluntary isometric contraction (MVC) the values of MUMCs and MUTs were around 11 mm/s2 and 7 mN, respectively. Already at these low effort levels the summation in MMG of single MUMCs of the recruited MUs is not linear. This may be due to the long duration of the MUMCs and to the changes in the muscle transverse and longitudinal compliance to mechanical stress determined by the overall MUs activity. On this basis the meaning of the MMG and force ripple oscillations (when larger of the peak to peak noise of the signals during rest and of the MUCMs and MUTs reported for single MUs) with respect to the MUs driving program has to be deeply investigated. This could be done by a cross analysis with the EMG which may partly disclose the central nervous system MUs activation strategy.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2009
• Tom: 69
• Numer: 3
• Opis fizyczny: p.289-290

Twórcy

autor

Orizio C.

• Department of Biomedical Science and Biotechnology, University of Brescia, Brescia, Italy

autor

Gobbo M.

• Department of Biomedical Science and Biotechnology, University of Brescia, Brescia, Italy

autor

De Grandis D.

• Department of Biomedical Science and Biotechnology, University of Brescia, Brescia, Italy

autor

Revenni R.

• Department of Biomedical Science and Biotechnology, University of Brescia, Brescia, Italy