## 1 Introduction
### Virtual Reality (VR) and Robotic-VR Combined Balance Training  
There is a need for balance training protocols that are accessible (with the potential to be transitioned to one's home environment) and engaging (particularly for those with limited mobility or access to healthcare facilities). Virtual reality (VR)-based training programs offer a promising alternative to traditional methods [10], providing balance and mobility exercises to older adults that are accessible (i.e., able to access in one's home), yet effective. Through immersive experiences, VR-based training programs may help older adults to practice balance and mobility exercises in a controlled setting, practiced within one's home, with the goal being to risk of falls and injuries through training. A growing body of evidence suggests that VR-based training programs can be effective in improving balance and reducing falls, particularly when compared to traditional training methods. For example, a 2019 systematic review and meta-analysis reported that VR-based training programs were more effective than traditional training methods in improving balance and reducing falls in older adults [10]. More recent studies indicate that VR-based interventions are highly effective in enhancing balance and gait in older adults. A 2020 randomized clinical trial comparing Virtual Reality Gait Training (VRGT) to standard treadmill training found that VRGT participants exhibited significant improvements in walking velocity, step width, stride length, and step length, reinforcing VR's potential in gait rehabilitation [16]. A 2021 study on immersive VR demonstrated that older adults with balance disorders who underwent VR-based balance training showed improved mobility and reduced dizziness symptoms compared to those receiving conventional physiotherapy. This suggests that immersive VR may provide superior benefits by addressing both sensory and mobility deficits [17]. Similarly, a 2021 randomized controlled trial examined Xbox Kinect-based VR exercises for fall-prone older adults. The results showed significant improvements in the Berg Balance Scale (BBS) and Timed Up and Go (TUG) test scores in the VR group. Furthermore, participants reported a notable reduction in the fear of falling, highlighting VR's psychological benefits in building confidence and reducing fall-related anxiety [18]. Although recent technological advancements, such as virtual reality (VR) and robotic-assisted balance training (RABT), have emerged as innovative tools for balance rehabilitation, there is limited research directly comparing the effectiveness of these two approaches in improving balance performance. The use of exoskeletons with VR, augmented reality, and gamification for balance training in survivors of stroke could aid patients in their recovery [11]. Further, it discussed the effectiveness of robot-assisted treatment as an innovative and engaging therapy. Because traditional therapy can become monotonous and exhausting for patients, the above treatments could increase motivation and adherence. However, more research is needed, and the above study focused on a specific population (survivors of stroke) limiting the generalizability of the findings to other patient groups [11]. It is essential to assess the effectiveness of these rehabilitation techniques across a wider range of older individuals. Here, we sought to examine if VR-based balance training or RABT has greater impacts on balance performance and perception in healthy older adults. Identifying effective methods is crucial for enhancing balance, thus reducing falls, in older adults. By investigating comparisons of innovative approaches, such as robotic and VR balance training, we aim to contribute to new knowledge which may ultimately lead to the development of more effective, personalized rehabilitation methods that can enhance mobility, independence, quality of life, and overall well-being for individuals aged 65 years old and older.