## 1 Introduction  
The stabilization of the human body is the basis for maintaining balance and enables the performance of selective, coordinated movements of the body [1, 2, 3]. The ability to synchronize rhythmically moving limbs and limb segments is one of the most basic abilities of vertebrate and invertebrate movement systems [4]. There are many definitions of motor coordination. One of them says that motor coordination is a combination of body movements created by kinematic (such as spatial direction) and kinetic (force) parameters that result in the intended actions [5, 6]. At the same time, coordinated movement is described by the appropriate speed, distance, direction, timing, and muscle tone [7]. As [PERSON] points out, these abilities are the main expression of how movements are organized in time and space, and the body is able to meet the competitive challenges of stability and flexibility [8]. On the other hand, it seems that a stable trunk is the most important element of the body posture control mechanism [9, 10, 11]. In patients after a stroke, the tension and strength of the superficial and deep stabilizing muscles are most often reduced. This leads to asymmetries and inappropriate movement patterns. Moreover, in the acute phase of stroke, most patients have reduced efficiency of the upper limb [12] and in the chronic phase, more than half of these patients still have a deficit in the mobility of the upper limb [13; 14; 15]. It should be noted that 80% of patients regain the ability to walk [16], and the recovery of the upper limb function is associated with long-term rehabilitation and does not meet many of the patients' expectations. The basis of this state of affairs is most likely a very large cortical (sensorimotor) representation of the upper limb, especially its distal part [17]. As a result of damage to the nervous structures, e.g., as a result of a stroke, the sensorimotor function is disturbed [14; 15; 17]. Therefore, it is worth investigating the use of various devices with which we could recover lost functions and activity in the upper limb. Scientists are constantly looking for new solutions. [PERSON] et al. recognized the use of repetition in therapy. He experimented with a glove to help coordinate hand movements, grasping, and squeezing. A glove was designed to support or resist a movement as needed when repeating a movement pattern [18]. Other researchers such as [PERSON] [19] and many other recommended the use of touch screen devices in therapy to recreate the strategy of movement and virtual reality to train the hand for bilateral coordination, adults with hemiplegia or hemiparesis, and children as well [20; 21; 22; 23; 24]. These devices most often use the principle of biofeedback. Biofeedback engages the brain to work, as a result of which the brain begins to learn, finding new possibilities to control, for example, muscles deprived of central control of movements [25; 26]. In recent years, transcranial magnetic stimulation with the use of non-invasive, mobile devices has also been used. The randomized, double-blind study showed an increase in the physiological activity of the brain in the areas near the damage [27; 28]. Owing to this, it is possible to improve many motor functions and activities, such as walking speed, hands force pressure, and arm movements [29]. Neurosurgical treatment was also used to stimulate the brain. It consists in implanting electrodes into areas of the brain in order to increase motor skills or their normalization [29; 30; 31]. In contrast to deep brain stimulation, another work has shown that repetitive sensory stimulation (rSS) induces sensorimotor improvement in the affected limb in patients with chronic stroke. After long-term rSS, all patients showed a significant improvement in sensory and motor skills.