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Exp Brain Res. 2011 Nov;215(2):101-13. doi: 10.1007/s00221-011-2875-9. Epub 2011 Oct 1.

Task-related variations in the surface EMG of the human first dorsal interosseous muscle.

Author information

1
National Rehabilitation Hospital, Neuroscience Research Center, 102 Irving Street NW, Washington, DC, 20010, USA. whitf026@umn.edu

Abstract

Evidence from human and animal studies suggests that motor neuron pool organization is not uniform for all motor tasks. Groupings of motor units within a muscle may be recruited differentially for a given task based on principles beyond anatomical or architectural features of the muscle alone. This study aimed to determine whether: (1) there was differential activation across locations of the first dorsal interosseous (FDI) muscle during a given task, (2) the differential activation was related to directional requirements and/or end goal of the task, and (3) there was an anatomical pattern to the differential activation. Twenty-six healthy right-handed participants carried out isometric finger/hand contractions in sitting while surface EMG was collected from 4 bipolar sites on the FDI muscle simultaneously. The tasks included: abduction, flexion, diagonal, 30% abduction + 30% flexion, 30% flexion + 30% abduction, key pinch, and power grasp. Mean peak integrated EMG for each task was normalized to site and task specific mean M waves. Differential activation was evident across FDI sites based on movement direction, order of directional components within a combination condition, and end goal of the task. There was greatest activation in the distal ulnar site for all tasks. Additionally there was a trend toward an ordering effect in the amount of activation at each site: distal ulnar > distal radial > proximal radial > proximal ulnar.

PMID:
21964867
DOI:
10.1007/s00221-011-2875-9
[Indexed for MEDLINE]

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