## 4 Discussion
An important factor of rehabilitation of elderly people, which should be considered, is a deterioration of cognitive functions during aging. This review mostly found exergames to be an acceptable and pleasant treatment. In most studies, exergames significantly improved various cognitive functions, as well as the quality of life among elderly with a risk of falling. Benefits regarding the health-related quality of life were also observed in elderly people who underwent virtual reality training. The level of satisfaction and enjoyment of such interventions was appraised positively [66]. There is also evidence of the positive motivational aspect of exergames among older adults [67]. In view of these qualitative outcomes, only a few authors have reported adverse effects, which were identified chiefly as non-related to intervention [38; 44; 45]. Incidentally, the comparison of adverse effects during VR rehabilitation in relation to traditional rehabilitation builds up another interesting research question. Although exergames were assessed as an effective intervention in alleviating symptoms of depression [68], the studies in this review do not confirm this thesis. However, differences in the results could be caused by the participants' level of functional abilities--there were elderly with decreased mobility; number of sessions--the duration was long; and the games' profile was centered around rehabilitation and functional performance, not enjoyment. [PERSON] et al. [68] indicated that the influence of exergames on depression is more effective in patients with relatively good mobility who play highly playful games in small numbers of sessions. Contemporary literature reviews regarding the effectiveness of virtual reality in orthopedic rehabilitation suggest that the variety of devices used, the variety of their functions, and a lack of coherence in applied protocols result are significant problems related to the comparison of the acquired results [69]. The analysis of the papers included in the current review also varied regarding the period of the intervention, adopted devices, and trained functions. A multitude of applied interventions and equipment, as well as a variety of tools and methods of evaluation of the effectiveness of those interventions, make it difficult to conduct a metanalysis. Conclusions of the analyzed studies do not allow to draw up any precise clinical guidelines regarding the duration, frequency, types of devices, and software implementations, as well as particular ailments and diseases in which virtual rehabilitation and exergames should be indicated. This review has some limitations because it concerned only randomized controlled trials published in the last 5 years in English. The reason is that RCTs are considered a gold standard in medical sciences and give reliable information about the effectiveness of the applied intervention [70]. In the last decade, there has been a rapid growth of VR clinical application papers published in PubMed [71]. Also, the quick development of modern technology meant that only the newest papers gave the opportunity to assess the current state of art in this topic. Therefore, there is a risk that other valuable reports would not be included in this review. In many studies, only clinical tests were used to assess physical outcomes, which provide valid results, but are fraught with a risk of bias due to human mistakes. Regarding those factors, future studies should use standardized biomechanical methods of assessment based on objective diagnostics tools. Common limitations of the included trials were the small sample size [29; 33; 37; 43; 45] and the lack of a long-term follow-up (6/21 studies with follow-up), as well as no blindness among participants and therapists (all studies). However, blindness in this kind of intervention is difficult to achieve but long-term follow-up and a proper study sample size are necessary to obtain reliable results. Exergames can be considered as an evolution to virtual reality, and vice versa.