title: The Movement- and Load-Dependent Differences in the EMG Patterns of the Human Arm Muscles during Two-Joint Movements (A Preliminary Study).
abstract: Slow circular movements of the hand with a fixed wrist joint that were produced in a horizontal plane under visual guidance during conditions of action of the elastic load directed tangentially to the movement trajectory were studied. The positional dependencies of the averaged surface EMGs in the muscles of the elbow and shoulder joints were compared for four possible combinations in the directions of load and movements. The EMG intensities were largely correlated with the waves of the force moment computed for a corresponding joint in the framework of a simple geometrical model of the system: arm - experimental setup. At the same time, in some cases the averaged EMGs exit from the segments of the trajectory restricted by the force moment singular points (FMSPs), in which the moments exhibited altered signs. The EMG activities display clear differences for the eccentric and concentric zones of contraction that are separated by the joint angle singular points (JASPs), which present extreme at the joint angle traces. We assumed that the modeled patterns of FMSPs and JASPs may be applied for an analysis of the synergic interaction between the motor commands arriving at different muscles in arbitrary two-joint movements.
authors.affiliation: Unit of the Theory of Sport and Motorics, Chair of Individual Sports, University of Physical Education and Sport Gdansk, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Tomiak
authors.affiliation: Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences Kiev, Ukraine.
authors.forename: Tetiana I
authors.initials: TI
authors.lastname: Abramovych
authors.affiliation: Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences Kiev, Ukraine.
authors.forename: Andriy V
authors.initials: AV
authors.lastname: Gorkovenko
authors.affiliation: Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences Kiev, Ukraine.
authors.forename: Inna V
authors.initials: IV
authors.lastname: Vereshchaka
authors.affiliation: Unit of the Theory of Sport and Motorics, Chair of Individual Sports, University of Physical Education and Sport Gdansk, Poland.
authors.forename: Viktor S
authors.initials: VS
authors.lastname: Mishchenko
authors.affiliation: Unit of the Theory of Sport and Motorics, Chair of Individual Sports, University of Physical Education and Sport Gdansk, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Dornowski
authors.affiliation: Department of Movement Physiology, Bogomoletz Institute of Physiology, National Academy of Sciences Kiev, Ukraine.
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Kostyukov
keywords: electromyogram; motor commands; motor control; muscle synergy; two-joint movements