Lower-limb neuromuscular responses to cognitive–motor dual-task stepping in healthy adults: implications for virtual reality-based rehabilitation

Background Virtual reality (VR) dual-task training is increasingly used to improve gait and balance in individuals with impaired postural stability. However, the neuromuscular mechanisms underlying these interventions remain underexplored. Objective This study aimed to compare lower-limb muscle activation during single- and dual-task VR stepping and evaluate how these responses differ from a validated dynamic balance test. Methods Twenty-one healthy adults completed the Four-Square Step Test (FSST) and two non-immersive VR tasks, high stepping (HS) and forward stepping (FS), under single- and dual-task conditions. Surface electromyography (sEMG) was recorded from bilateral Biceps Femoris, Rectus Femoris, Gluteus Medius, Lateral Gastrocnemius, and Soleus. Two-way repeated ANOVAs assessed the effects of task type and cognitive load on mean sEMG amplitude; one-way ANOVAs compared activation between the FSST and VR tasks. Results Cognitive load significantly reduced muscle activation during FS for most muscles ( p  < 0.001–0.032), but not during HS. Activation was generally higher in FS than HS, particularly under single-task conditions. Compared with FSST, muscle activation was significantly lower in VR tasks ( p  < 0.05). Interaction effects between task type and cognitive load were observed for most muscles, with large effect sizes. Conclusions Cognitive load influenced neuromuscular control during VR stepping, particularly in complex tasks like FS. While VR tasks elicited lower activation than FSST, they engaged key postural muscles and may offer adaptable, lower intensity options for rehabilitation. These findings provide normative data to guide VR-based interventions for population with impaired postural stability.