Avtor/Urednik		Holobar, Aleš; Gazzoni, Marco; Farina, D.; Zazula, Damjan; Merletti, Roberto
Naslov		Non-invasive estimation of the degree of motor unit synchronization in the biceps brachii muscle
Tip		članek
Vir		In: Jarm T, Kramar P, Zupanič A, editors. Medicon 2007. IFMBE proceedings from the 11th Mediterranean conference on medical and biological enginering and computing; 2007 Jun 26-30; Ljubljana. New York: Springer,
Leto izdaje		2007
Obseg		str. 109-13
Jezik		eng
Abstrakt		This paper addresses estimation of motor unit (MU) synchronization by means of surface electromyogram decomposition. Firstly, the so called convolution kernel com-pensation method for identifying the discharge patterns of individual motor unjts is briefly described. The method builds on independent component analysis framework and is, hence, highly robust to superimpositions of MU action potentials (AP). In this study, the method was tested with synthetic signals in presence of MU synchronization, when the MU discharges are not strictly independent anymore. The level of MU synchronization was measured by the cross-interval histo-grams of reconstructed MU discharge patterns. Two synchro-nization indices were computed: the average number of syn-chronized MU pairs per contraction and the average percentage of synchronized AP per synchronized MU pair. Results revealed that both indices vary substantially with the properties of reconstructed MUs, but can nevertheless be used as reliable estimators of MU synchronization. The method was then applied to experimental electromyographic signals, acquired during low forte contractions of the dominant biceps brachii muscle. Up to 14 concurrently active MUs were identified. MU synchronization was observed in approx. 50% of MU pairs. It is thus concluded, that MU synchronization can be assessed by decomposing the surface electromyogram.