The excitability of the motoneurons innervating the antagonist muscles are depressed by reciprocal inhibition (De Gail et al.
When the vibratory stimulus is applied to an agonist muscle it causes reciprocal inhibition of the antagonist motoneurons (Bishop, 1974); but when vibration is applied simultaneously to the agonist and antagonist muscles, the facilitatory effect of each muscle group is inhibited (Hagbarth, 1967).
Thus while obtaining the external attentional focus, the decrease of level of electrical activity of muscles creates some kind of appropriate coordination between the group of Agonist & Antagonist muscles and it brings about the automatic control in execution [11, 24- 26].
Additionally, shooting based on the more muscle contraction instruction (internal focus) results in increase of electrical activity in muscles and the coordination between the agonist and antagonist muscles are not formed for automatic control.
As stated above, synkinesis is the simultaneous nerve-instigated contraction of antagonist muscles
In case of decreased stiffness, the resistance of antagonist muscles
will be smaller [14, 16].
The fact that there is no linear relation here is probably because of the speed of charge disk of motor units, and decrease in recruitment of motor units and reduction in co-activation of antagonist muscles
The movement is stopped by contraction of the antagonist muscles
The simultaneous contraction in antagonist muscles
that results is called "synkinesis.
Thus, changing the inter-electrode distance was tested to determine if this resulted in a more selective stimulation of the BB through minimizing current spread and reducing co activation of synergistic and antagonist muscles.
Background sEMG of agonist & antagonist muscles
Despite these facts, a smooth stair descent requires good coordination of the agonist and antagonist muscles
that regulate joint stiffness during the descent.
In elderly, this phenomenon elevates antagonist muscles
activity, which increases muscle coactivity (Izquicrdo et al.