Effect of local modulation of a real-time self-avatar on 3D gait kinematics during natural walking on a treadmill

Virtual reality (VR) has found many uses in physical and motor rehabilitation in recent years. VR offers new possibilities for altering a user's visual self-representation using a self-avatar that replicates his movements accurately, or modifies them by incorporating modulations in real-time. The objective of this study is to quantify the variations in gait kinematics of subjects when the lower-limb movements of their virtual self-avatar are altered. In this study, ten subjects were evaluated. They walked on an instrumented split-belt treadmill while viewing their self-avatar from either a first person perspective or a third person perspective. After a habituation period, the flexion angle of the right hip of the avatar was increased which resulted in an asymmetrical gait pattern. Gait parameters were compared between the different conditions to establish if the subject tends to change his gait in order to follow the self-avatar's gait. Interestingly, the subjects increased their hip extension when presented with their unmodulated self-avatar. Modulation of the avatar did not lead to any consistent changes across the studied subjects. Possible explanations are discussed.