Changes in muscle geometry during forearm pronation and supination and their relationships to EMG cross-correlation measures

Abstract Geometric artifact may alter the amplitude and frequency of the electromyography (EMG) signal. Artifacts include the changing geometry of muscles with respect to electrodes and potential crosstalk from adjacent muscles. This study addresses: (1) the geometrical relationships between common...

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Bibliographic Details
Published in:Journal of electromyography and kinesiology 2013-06, Vol.23 (3), p.664-672
Main Authors: Yung, M, Wells, R.P
Format: Article
Language:English
Subjects:
Adult
Analysis of Variance
Cross-correlation
Crosstalk
Electromyography
Female
Forearm - physiology
Forearm rotation
Hand Strength - physiology
Humans
Male
Muscle Contraction - physiology
Muscle, Skeletal - diagnostic imaging
Muscle, Skeletal - physiology
Physical Medicine and Rehabilitation
Pronation - physiology
Sonography
Supination - physiology
Ultrasonography
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Summary:Abstract Geometric artifact may alter the amplitude and frequency of the electromyography (EMG) signal. Artifacts include the changing geometry of muscles with respect to electrodes and potential crosstalk from adjacent muscles. This study addresses: (1) the geometrical relationships between common electrode placement sites for six forearm muscles, (2) the geometrical change of forearm muscles in pronation and supination, and (3) the relationships between EMG cross-correlation and muscle geometry. EMG and ultrasonography images were recorded during pronation, supination, and neutral forearm postures while exerting 20% maximum grip strength. Proportions of anatomical structures were then calculated for 15 mm, 20 mm, and 25 mm radial pick-up zone distances, representing greater than 90% of observed myoelectrical signal energy. We found that guidelines for electrode placements were supported and no single posture maximized the proportion of the target muscle detected. Secondly, other muscles were present in the most conservative 15 mm radius pick up zone; it is unlikely that surface EMG can completely differentiate between forearm muscle activities. Thirdly, forearm orientation did not appear to be an important factor in changing the geometrical relationships between surface electrodes and the muscles studied, and fourthly, certain muscles (e.g., FDS) may be more vulnerable to EMG crosstalk.
ISSN:1050-6411
1873-5711
DOI:10.1016/j.jelekin.2013.01.001