Dynamics of Parameters of Low-Amplitude Hand Movements in a Repetitive Motor-Cognitive Task

In contrast to the development of muscle adaptations associated with overstrain, insufficient stretching, overloading, and underloading, use of short-term courses of low-strain motor-cognitive training induces adaptation linked with neural rearrangements, studies of which are of great interest. This direction remains insufficiently studied as indicated, for example, by the fact that motor activity regimes in medical rehabilitation are selected empirically and the difficulty of prognostication and assessment of rehabilitation potential. In these studies, 25 healthy pretrained volunteers applied force to an immobile joystick with the hand to control a label on a screen with the aim of studying the ability to follow instructions and the force characteristics of low-amplitude control movements. A joystick attached to a force platform was used to assess measures of the trajectory of the center of pressure on the support, the vertical force, and the external result (the extent of following the instruction in terms of the mean duration of processing a single result) on performance of a standard task with visual feedback carried out three times with each hand sequentially over four days (short training course). Data were analyzed using standard mathematical methods. A stable level of following instructions was achieved extremely quickly – by the second session. Optimization of vertical pressure force occurred during the second course, while optimization of control in the plane of the support was more difficult. “Optimization” of motor control (for a given observation period) and adaptive processes proceeded nonuniformly for different aspects of control: achievement of optimal productivity, selection of vertical force, and manipulation of force in the plane of the support. The rapid improvements in results obtained from following instructions were presumptively linked with optimization of the strategy. The task of optimizing vertical force on the joystick was more difficult, while the most difficult was control of hand force in the plane of the support, which may be associated with the fact that this was linked with a later stage of training. © 2021, Springer Science+Business Media, LLC, part of Springer Nature.