## 4 Discussion  
In this study, we compared the performance in a VR game between TD children and children with DCD, and explored the correlations between the performance of children with DCD in the game and the MABC. Our main findings were that the VR game score was able to discriminate between TD children and children with DCD. Also, in the DCD group, the hand path length strongly correlated with the visual-motor coordination MABC subcategory score and with the balance MABC subcategory score, as well as with the total MABC score. This is the first study that presents such findings in the young population of 5-year old children, and our results place the foundation for future validation of this tool as a measuring instrument for children with DCD. The similarity in hand path lengths recorded while playing the VR game between TD children and children with DCD was also noted in the older population of TD children and children with DCD playing VR games [17]. The authors reported faster hand movement for the TD children. This might explain the higher score achievements of TD children in our study, despite the similar hand path length. Another explanation might be the degree of accuracy required to hit the targets, so that while both groups managed to reach the proximity of the targets, the control group was more adept in accurate localization of the end point, and therefore better scores were achieved. The similarity in COP movement pattern between children with DCD and TD children indicates that both groups incorporated similar postural maneuvers while playing the game. This finding suggests that a pressure sensing pad may not be an appropriate tool to discriminate between TD children and children with DCD, while playing a simple VR game that does not require lower limb movement. This finding is surprising since a previous study that compared 64 children with DCD and 71 TD 10-year-old children reported statistically significant differences in the COP path while the subjects stood quietly with their eyes open [24]. These differences, however, were not found in this study, possibly due to the different cognitive functions required while standing and while playing a VR game, which results in different mechanisms of balance control being used. In the DCD group, there were no statistically significant correlations between the COP parameters and the MABC scores. We expected mild correlation with the balance subcategory, as COP is usually associated with balance control. However, the chosen gaming activity was not challenging in terms of balance perturbation, as opposed to the balance challenge introduced during the MABC test. So, we surmise two important notes: firstly, the COP data collected during upper limb VR gaming are  
Figure 1: The visual-motor coordination Movement Assessment Battery for Children (MABC) subcategory scores as a function of the recorded right-hand path length while playing a virtual reality game for activation of the upper limbs. Data are presented for children with Developmental Coordination Disorder (DCD). Note: when removing an outlier in the right-hand path length data from this group, found using [PERSON]’s test, the R\({}^{2}\) = 0.717.  
irrelevant for the evaluation of DCD; secondly, the upper limb VR game, chosen for this study, produces minimal movements of the COP and may therefore be considered safe (i.e., bearing negligible risk of falling) for children with balance impairments. In the DCD group, the right-hand path length strongly correlated with the visual-motor coordination MABC subcategory score (r = 0.902, \(p\) < 0.001). This finding points to a possible added value of collecting kinematics data from upper limb VR gaming, as they might be of value in a preliminary evaluation of visual-motor coordination. The VR task presented to the children in this study was more demanding, in terms of required accuracy for success and duration of the task, compared with the short tasks of catching a beanbag and rolling a ball towards a target in the MABC.