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Extracting extensor digitorum communis activation patterns using high-density surface electromyography.

Hu X, Suresh NL, Xue C, Rymer WZ - Front Physiol (2015)

Bottom Line: Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance.We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction.Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

View Article: PubMed Central - PubMed

Affiliation: Sensory Motor Performance Program, Single Motor Unit Lab, Rehabilitation Institute of Chicago Chicago, IL, USA.

ABSTRACT
The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions. The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7 × 9) surface electromyogram (EMG) recordings. The muscle activation map (based on the root mean square of the EMG) was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic). Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

No MeSH data available.


Related in: MedlinePlus

Average RMS within each grid in different tasks. Error bars represent standard errors between subjects.
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Figure 2: Average RMS within each grid in different tasks. Error bars represent standard errors between subjects.

Mentions: The levels of extensor digitorum communis activation estimated from the mean RMS-values across 63 channels are illustrated in Figure 2. The highest mean RMS-value (during four-finger extension at high effort) within a subject was used to normalize the mean RMS-value, because the RMS-value varies considerably across subjects. As expected, the muscle activation level was significantly higher during high effort finger extension than during low effort conditions [F(1, 9) = 34.91, p = 0.001]. No significant interactions (p > 0.05) were found between finger (individual fingers vs. whole hand), effort level (high vs. low), and finger-constraint (dynamic vs. static). A significant difference in the RMS at different finger tasks was evident [F(4, 36) = 29.26, p = 0.001]. The post hoc analysis showed that the RMS was higher in four-finger task compared with all the individual finger tasks (p < 0.05), and that the RMS in little finger extension was lower than the RMS in index and ring finger extension tasks (p < 0.05). The activation level was not significantly different between the dynamic and static extension tasks [F(1, 9) = 0.24, p = 0.64].


Extracting extensor digitorum communis activation patterns using high-density surface electromyography.

Hu X, Suresh NL, Xue C, Rymer WZ - Front Physiol (2015)

Average RMS within each grid in different tasks. Error bars represent standard errors between subjects.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593961&req=5

Figure 2: Average RMS within each grid in different tasks. Error bars represent standard errors between subjects.
Mentions: The levels of extensor digitorum communis activation estimated from the mean RMS-values across 63 channels are illustrated in Figure 2. The highest mean RMS-value (during four-finger extension at high effort) within a subject was used to normalize the mean RMS-value, because the RMS-value varies considerably across subjects. As expected, the muscle activation level was significantly higher during high effort finger extension than during low effort conditions [F(1, 9) = 34.91, p = 0.001]. No significant interactions (p > 0.05) were found between finger (individual fingers vs. whole hand), effort level (high vs. low), and finger-constraint (dynamic vs. static). A significant difference in the RMS at different finger tasks was evident [F(4, 36) = 29.26, p = 0.001]. The post hoc analysis showed that the RMS was higher in four-finger task compared with all the individual finger tasks (p < 0.05), and that the RMS in little finger extension was lower than the RMS in index and ring finger extension tasks (p < 0.05). The activation level was not significantly different between the dynamic and static extension tasks [F(1, 9) = 0.24, p = 0.64].

Bottom Line: Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance.We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction.Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

View Article: PubMed Central - PubMed

Affiliation: Sensory Motor Performance Program, Single Motor Unit Lab, Rehabilitation Institute of Chicago Chicago, IL, USA.

ABSTRACT
The extensor digitorum communis muscle plays an important role in hand dexterity during object manipulations. This multi-tendinous muscle is believed to be controlled through separate motoneuron pools, thereby forming different compartments that control individual digits. However, due to the complex anatomical variations across individuals and the flexibility of neural control strategies, the spatial activation patterns of the extensor digitorum communis compartments during individual finger extension have not been fully tracked under different task conditions. The objective of this study was to quantify the global spatial activation patterns of the extensor digitorum communis using high-density (7 × 9) surface electromyogram (EMG) recordings. The muscle activation map (based on the root mean square of the EMG) was constructed when subjects performed individual four finger extensions at the metacarpophalangeal joint, at different effort levels and under different finger constraints (static and dynamic). Our results revealed distinct activation patterns during individual finger extensions, especially between index and middle finger extensions, although the activation between ring and little finger extensions showed strong covariance. The activation map was relatively consistent at different muscle contraction levels and for different finger constraint conditions. We also found that distinct activation patterns were more discernible in the proximal-distal direction than in the radial-ulnar direction. The global spatial activation map utilizing surface grid EMG of the extensor digitorum communis muscle provides information for localizing individual compartments of the extensor muscle during finger extensions. This is of potential value for identifying more selective control input for assistive devices. Such information can also provide a basis for understanding hand impairment in individuals with neural disorders.

No MeSH data available.


Related in: MedlinePlus