The analysis of movement trajectory (closer, farther, contralaterally, ipsilaterally) is becoming more and more relevant to the rehabilitation of post-stroke patients. This is supported by one of the hypotheses based on the theory of reorganization of cortical brain structures, which indicates the need for rehabilitation in the form of bilateral task performance involving both paretic and non-paretic cerebral hemispheres [16, 17]. Quantitative motion analysis provides information on the motor compensation strategies used by stroke patients, and is therefore of considerable clinical relevance , as it reveals the patient’s current condition and allows comparisons with healthy controls .
The used kinematic parameters, i.e. JERK and TIME, facilitate clinical studies of patients in terms of motion analysis, and can be useful not only for better rehabilitation planning but also for enhancing the effective application of technology-based devices . One of the main advantages of this method is also the detection of individual deficits, which may remain invisible in the traditional patient assessment process. Hussain et al.  argue that kinematic analysis can provide valuable and specific information about sensorimotor impairment of the upper limb following stroke that might not be captured using traditional clinical scales. Our research confirms this argument since the analysis of the trajectory of movement ipsilaterally showed no differences, which is not revealed in traditional assessment. Such information can make the patients realize the need for further rehabilitation in this area.
Trajectory analysis also makes it possible to develop a reliable reference scale for healthy people [20, 21]. Otaka et al.  noted that arm movements in hemiparetic stroke patients were slower, less accurate, less smooth, and more segmented than in healthy controls. In the present study the imaging of movement demonstrated that toward the end of the movement its trajectory was often found to be clustered in post-stroke patients, resembling a spider’s web. Similar conclusions were reached by Hussain et al. . Movement time and trajectory are frequently tested in fast pointing movements using motion capture systems, and are considered key variables for kinematic movement analysis of upper limb tasks in stroke [12, 13]. The present study confirms their significance by way of performing a task of indicating a determined point by a group of post-stroke patients.
The authors of this paper also stress the possibility of using the above methodology to determine patients’ individual deficits and pathological compensatory movements. The validity of determination of compensation levels and diagnosis of deficits were also discussed by other authors [8, 23]. They showed that during the reaching for an object the patients displayed a reduced arm elongation and trunk axial rotation due to motor deficit. It was related to their use of compensatory strategies which included trunk forward displacement and extra head movements. The generated specific movement compensation is closely related to the movement trajectory and the placement of objects reached for by a patient .
The study of movement trajectory appears to be a promising stroke assessment tool. Further research is still necessary to assess the relationship between its outcome variables and clinical measures of upper extremity impairment. This type of research proves the need to use the tools we use to support the diagnostic process of rehabilitation, however, the researchers are aware that there is still a long way to go, due to the cost and process of processing the collected information. We are also aware that the development of modern information technology will significantly simplify this system.