## 4 Discussion
Maintaining performance revealed that the simulator enables the athlete to behave in a natural and spontaneous way (biomechanical fidelity), that the athlete uses the same perceptual information to control their movement (psychological fidelity), and, above all, proves that the simulator is able to correctly measure user behavior (construct validity). In this study, the validity and fidelity of a VR relay simulator were tested in the most exhaustive way through numerous complementary measures. The evaluation showed that the simulator accurately reproduced the task constraints, allowing the athletes to behave as if they were on the track, while providing a reliable tool for measuring performance. Although the results largely support the validity and fidelity of the simulator, the sample size of this study remains rather small, and it will be interesting to compare the behaviors of a larger number of athletes. A larger-scale comparison could provide more confident results in terms of behavior preservation in the virtual task and also give the possibility of clustering individual athletes' strategies. It would also be interesting to carry out a more in-depth comparison of motor behavior using other analyses such as Spatial Parametric Mapping (SPM) or using another kinematic measurement system independent of the simulator. Once this work has been completed, it will be necessary to continue the work initiated by [PERSON] et al. by using the simulator as a tool for characterizing athletes' performance [13]. Furthermore, it is essential to point out that the validity and fidelity of the simulator are not sufficient to guarantee a potential transfer of learning to reality but are part of the methodological precautions that maximize the chances of obtaining it [15]. This type of study aims to prove that VR is a suitable tool for perceptual-motor training, provided that the validity and fidelity criteria are met. Their measurements should therefore be an integral part of the design process for future simulators. It should be noted that the 4 \(\times\) 100 m relay is a simple sporting discipline to replicate virtually, compared with others such as team sports. The absence of haptic feedback is a huge limit for most virtual environments. However, the relay initiation task does not require any haptic feedback. The decision-making process is based on visual information about the incoming partner, and that is why this motor task is compatible with a virtual environment. On the other hand, depth perception is indeed a potential limit of the simulator, and it would be relevant to test whether distance perception is biased in virtual reality. But according to [PERSON] [15], good psychological fidelity can be absolute or relative. Absolute psychological fidelity means that every variable of the environment is identical to reality. Relative psychological fidelity means that although some variables differ, like distance perception, they vary proportionally. Absolute psychological fidelity is optimal for the transfer of training, but relative fidelity is also functional. Moreover, depth perception bias can be overcome by immersing free-moving athletes in rich and structured virtual environments, providing them with a large amount of motion parallax and other sources of information, which is well documented to greatly attenuate virtual misperception [32]. The challenge for the years to come will be to create valid and faithful simulators for more complex sports. Assuming that the results of this study are encouraging, the next step will be to assess whether training athletes' anticipation skills using the simulator is a method transferable to the field. With these methodological precautions having now been taken, it is time to start using the simulator as a training tool to measure performance improvements in the real world. As mentioned above, it would also be a matter of completing the work on characterizing the different types of anticipation behavior.