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Spatio-temporal processing of surface electromyographic signals: information on neuromuscular function and control
Umeå University, Faculty of Medicine, Department of Radiation Sciences.
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

During muscle contraction, electrical signals are generated by the muscle cells. The analysis of those signals is called electromyography (EMG). The EMG signal is mainly determined by physiological factors including so called central factors (central nervous system origin) and peripheral factors (muscle tissue origin). In addition, during the acquisition of EMG signals, technical factors are introduced (measurement equipment origin). The aim of this dissertation was to develop and evaluate methods to estimate physiological properties of the muscles using multichannel surface EMG (MCsEMG) signals.

In order to obtain accurate physiological estimates, a method for automatic signal quality estimation was developed. The method’s performance was evaluated using visually classified signals, and the results demonstrated high classification accuracy.

A method for estimation of the muscle fibre conduction velocity (MFCV) and the muscle fibre orientation (MFO) was developed. The method was evaluated with synthetic signals and demonstrated high estimation precision at low contraction levels.

In order to discriminate between the estimates of MFCV and MFO belonging to single or populations of motor units (MUs), density regions of so called spatial distributions were examined. This method was applied in a study of the trapezius muscle and demonstrated spatial separation of MFCV (as well as MFO) even at high contraction levels.

In addition, a method for quantification of MU synchronisation was developed. The performance on synthetic sEMG signals showed high sensitivity on MU synchronisation and robustness to changes in MFCV. The method was applied in a study of the biceps brachii muscle and the relation to force tremor during fatigue. The results showed that MU synchronisation accounted for about 40 % of the force tremor.

In conclusion, new sEMG methods were developed to study muscle function and motor control in terms of muscle architecture, muscle fibre characteristics, and processes within the central nervous system.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2006. , p. 97
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1078
Keywords [en]
EMG, multichannel surface electromyography, motor unit action potentials, conduction velocity, muscle architecture, signal quality, spatial distributions, synchronization, muscle function, motor control
National Category
Medical Engineering
Research subject
Biomedical Radiation Science
Identifiers
URN: urn:nbn:se:umu:diva-958ISBN: 978-91-7264-239-3 (print)ISBN: 91-7264-239-4 (print)OAI: oai:DiVA.org:umu-958DiVA, id: diva2:145189
Public defence
2007-01-12, Lionssalen (sal 244), 7, NUS, Umeå, 13:00 (English)
Opponent
Available from: 2006-12-22 Created: 2006-12-22 Last updated: 2018-06-09Bibliographically approved
List of papers
1. On-line signal quality estimation of multichannel surface electromyograms
Open this publication in new window or tab >>On-line signal quality estimation of multichannel surface electromyograms
2005 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, no 3, p. 357-364Article in journal (Refereed) Published
Keywords
Surface electromyography, multichannel, impedance, quality estimation, on-line, multivariate outlier detection
National Category
Neurosciences Physiology
Identifiers
urn:nbn:se:umu:diva-13993 (URN)16035224 (PubMedID)
Available from: 2006-11-08 Created: 2006-11-08 Last updated: 2018-06-09Bibliographically approved
2. Simultaneous estimation of muscle fibre conduction velocity and muscle fibre orientation using 2D multichannel surface electromyogram
Open this publication in new window or tab >>Simultaneous estimation of muscle fibre conduction velocity and muscle fibre orientation using 2D multichannel surface electromyogram
2005 (English)In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 43, no 1, p. 63-70Article in journal (Refereed) Published
Keywords
Surface electromyography, EMG, multichannel, conduction velocity, fibre orientation, motor unit
National Category
Physiology Neurosciences
Identifiers
urn:nbn:se:umu:diva-14169 (URN)15742721 (PubMedID)
Available from: 2006-11-08 Created: 2006-11-08 Last updated: 2018-06-09Bibliographically approved
3. Spatial distribution of active muscle fibre characteristics in the upper trapezius muscle and its dependency on contraction level and duration
Open this publication in new window or tab >>Spatial distribution of active muscle fibre characteristics in the upper trapezius muscle and its dependency on contraction level and duration
2008 (English)In: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 18, no 3, p. 372-381Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to provide direct in vivo information of the physiological and structural characteristics of active muscle fibres from a large part of the upper trapezius muscle. Two-dimensional (2-D) multi-channel surface electromyography recordings were used, with 13 × 10 electrodes covering 6 × 4.5 cm of the skin’s surface. A previously developed method was applied to detect individual propagating motor unit action potentials and to estimate their corresponding muscle fibre conduction velocity (MFCV) and muscle fibre orientation (MFO). Using these estimates, spatial distributions of MFCV and MFO were examined for five male subjects performing isometric shoulder elevation at different force levels. The main results were: (1) the general relationship between MFCV and force generation was non-systematic, with a positive relationship at the inferior part of the muscle, (2) the spatial distribution of MFCV at different force levels and fatigue was inhomogeneous and (3) the MFO was slightly different (6°) of the muscle fibres with origin superior compared to inferior to the C7 vertebra. These findings provide new information of the MFO of contracting muscle fibres and knowledge of the physiological characteristics of a large part of the upper trapezius muscle that previously was based on observations from human cadavers only.

Place, publisher, year, edition, pages
Elsevier, 2008
Keywords
Muscle fibre conduction velocity, muscle architecture, inhomogeneous activation, multi-channel surface EMG, fatigue
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-10002 (URN)10.1016/j.jelekin.2006.12.003 (DOI)000256600400003 ()17276698 (PubMedID)
Available from: 2008-06-04 Created: 2008-06-04 Last updated: 2020-01-23Bibliographically approved
4. Quantification of motor unit synchronization from surface EMG signals with minimized dependency on muscle fibre conduction velocity
Open this publication in new window or tab >>Quantification of motor unit synchronization from surface EMG signals with minimized dependency on muscle fibre conduction velocity
(English)Manuscript (preprint) (Other academic)
National Category
Neurosciences Physiology
Identifiers
urn:nbn:se:umu:diva-5613 (URN)
Available from: 2006-12-22 Created: 2006-12-22 Last updated: 2018-06-09Bibliographically approved
5. Fatigue induced changes in motor unit synchronization and its relation to force tremor in different parts of the biceps brachii muscle
Open this publication in new window or tab >>Fatigue induced changes in motor unit synchronization and its relation to force tremor in different parts of the biceps brachii muscle
(English)Manuscript (preprint) (Other academic)
National Category
Neurosciences Physiology
Identifiers
urn:nbn:se:umu:diva-5614 (URN)
Available from: 2006-12-22 Created: 2006-12-22 Last updated: 2018-06-09Bibliographically approved

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Grönlund, Christer

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