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International Journal of Physiology and Pathophysiology
SJR: 0.116

ISSN Print: 2155-014X
ISSN Online: 2155-0158

Archives: Volume 1, 2010 to Volume 9, 2018

International Journal of Physiology and Pathophysiology

DOI: 10.1615/IntJPhysPathophys.v7.i2.20
pages 105-117

Comparative Analysis of Electromyographic Muscle Activity of the Human Hand during Cyclic Turns of Isometric Effort Vector of Wrist in Opposite Directions

Oleksiy V. Lehedza
Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
Andriy V. Gorkovenko
Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
Iryna V. Vereshchaka
Academy of Physical Education and Sports, Gdansk, Poland
M. Dornowski
Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
Oleksandr I. Kostyukov
Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine

ABSTRACT

The features of the targeted tonic isometric effort, created by the shoulder girdle and the shoulder muscles, were compared for two opposing one another changes in the directions of arbitrary force vector, namely clockwise and counterclockwise rotation. The magnitude of the force vector remained constant. The intensity of central motor commands (CMC) was assessed from the calculated area of rectified, averaged and approximated electromyograms (EMG) recorded from the investigated muscles. The effort development in determined direction was carried out in the operation space of the horizontal plane at the angles of 75° in the shoulder joint and 90° in the elbow one. The synergic interaction of individual functional groups of muscles under a certain force response was found. Spatially, the areas of prevailing activity of the certain muscles within the operating space were determined. The differences were shown in the levels of EMG amplitude for force vectors' opposing directions, as well as co-activation of the flexor muscles, while the extensor muscles showed their activity only within their functional sectors. Half of the investigated muscles demonstrated an increase in the EMG amplitude for counterclockwise direction compared to the EMG amplitude in clockwise direction. This fact can be attributed to more complex organization of motor commands which are consistently addressed to the muscles of the shoulder and the forearm in response to atypical sequence of antagonist muscle activation during making cyclic movements by the hand in the mode of tonic isometric contraction.