###### Abstract  
In this paper, the authors analysed changes occurring during the rehabilitation processes in patients after early stroke based on analysis of their upper limbs' target-reaching movement and muscle co-activation. Ischemic stroke often results in reduced mobility of the upper extremities and frequently is a cause for long-term disability. The ever-developing technology of 3D movement analysis and miniaturisation of equipment for testing the bioelectrical activity of muscles can help to assess the progress of rehabilitation. The aim of this study was to examine the use of analysis of target-reaching movement indicators and muscle co-activation for diagnosing the rehabilitation process in post-stroke patients. Twenty ischemic stroke patients in the early post-stroke phase (up to three months after the stroke), and twenty healthy subjects (the control group) took part in the experiments. The novel approach of the proposed research proved the usefulness of this approach in the diagnosis of the rehabilitation efficiency of rehabilitation in early post-stroke phase patients. rehabilitation; stroke; biomedical data; statistical analysis +
Footnote †: journal: Medical  
scales tend to have a ceiling effect since they rely on scoring criteria rather than on a continuous measurement construct [7]. There have been numerous studies of rehabilitation progress with the assistance of kinematic analysis [6; 8; 9] in particular, with robotic exoskeletons (see: [10]). The applied devices support the motion of the shoulder girdle and the whole upper extremity. They significantly facilitate patients' movement and allow registering the rehabilitation progress. The study of problems related to human motor skills can contribute to the implementation of better rehabilitation at the immediate and chronic stages after stroke. The current technology offers a number of kinematic indicators, which can be efficient parameters for objective functional assessment of the upper limb in people with movement disorders [11; 12]. The majority of kinematic studies on stroke patients have focused on such parameters of accuracy of location in motion as close or far, low or high, and with or without clearance in front of the person. There were also studies involving different grasping tasks [13; 14]. The task used in our research is similar to routine tasks of daily living, such as interacting with touchscreens or pressing buttons on different devices. Advantages of the analysis of trajectories of movement systems as a measurement tool include standardized instructions, adaptation of tasks according to patients' functioning level, and the availability of quick feedback. Additional information regarding the progress in rehabilitation may be provided through the analysis of the bioelectric activity of selected muscles of the examined limb. It is advisable to use the surface electromyography (sEMG) for this purpose, which determines the level of dependence of the bioelectric activity of individual muscles in the upper limb during simple motor activities. Depending on the hypothesis related to disturbed bioelectric activity, researchers used sEMG as a tool to analyse muscle activity during the stretching of relaxed agonist and antagonist muscles [12], or to determine muscle co-activation between the triceps brachii and biceps brachii muscles, Ref. [15] used surface electromyography as a tool to diagnose the activity of eight muscles of the upper limb with a shoulder girdle during the training of eight different movement patterns among patients after stroke. The obtained results showed statistically significant differences in the jerk and CI parameters between the study before and after the rehabilitation process (jerk closer PRE 0.28 \(\pm\) 0.14 and POST 0.11 \(\pm\) 0.10, jerk further PRE 0.75 \(\pm\) 0.57 and POST 0.26 \(\pm\) 0.13), as well as no differences between the experimental and control groups.