A Comparison of Postural Responses in a Virtual and a Real Environment, a Randomised Controlled Study.

Background: Immersive virtual reality solutions are seeing increasing usage in functional rehabilitation programmes. However, there is no reference that allows us to confirm that these environments present the same characteristics and therefore the same degree of safety and training in postural responses for balance. Question The aim of the study was to compare displacements from centre of gravity (distance covered and surface used) in balance tests, comparing the real situation to an identical virtual situation. Participants 70 healthy subjects aged between 18 and 65 were recruited in two centres. Design: The study used a one-way repeated-measures design with randomisation of the order in which the two test conditions were performed. Intervention: . The first test condition was "real", taking place in a bedroom of a treatment centre apartment, and the second was virtual, with the room reproduced and seen through a HMD. For each condition, two static tests (left leg, right leg) and two dynamic tests (left and right) were performed. Each test included three attempts. Outcome measures The displacement from the centre of gravity was recorded on a force plate. Result: 69 participants completed all of the tests and were analysed. None of the tests resulted in confirmation that the virtual was equivalent to the real (Two One-Sided Tests for left static, right static, left dynamic, right dynamic; surface respectively p = 0.592, p = 0.151, p = 0.238, p = 0.503; distance respectively p = 1.00, p = 0.91, p = 0.0742, p = 1.00). Furthermore 6 tests of out 8 showed a significant and considerable difference (surface respectively p = 0.00249, p = 0.0664, p = 0.0318, p = 0.00483; distance respectively p = 1.12 x 10-8, p = 5.27 x 10-5, p = 0.153, p = 2.55 x 10-9). Conclusion: Postural responses were poorer in the immersive virtual environment, both on the static and dynamic balance tests. The offer of balance rehabilitation in immersive VR raises safety issues and consequently ethical issues that are as yet unresolved. Researchers must test solutions to correct this serious problem. Trial registration The study is registered at the US National Institutes of Health (ClinicalTrials.gov) NCT04574726