Influence of task difficulty on lower-limb muscle activation during non-immersive virtual reality balance tasks [Abstract]

Whidborne, J. and Al-Amri, M. ORCID: https://orcid.org/0000-0003-2806-0462 2026. Influence of task difficulty on lower-limb muscle activation during non-immersive virtual reality balance tasks [Abstract]. Physiotherapy 132 (S1) , 102006. 10.1016/j.physio.2026.102006

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Abstract

Purpose: Virtual reality (VR) is increasingly utilised in rehabilitation of neurological and musculoskeletal conditions due to its demonstrated benefits in improving gait, balance, and aerobic capacity. For rehabilitation of neurological populations such as Parkinson’s disease, multiple sclerosis and stroke, VR-based interventions have also been linked to improvements in dual-task performance (Spanò et al. 2022). However, little is known about how muscle activation differs between single- and dual-task VR activities. Understanding these differences is crucial to ensure VR effectively engages muscles critical for postural stability, particularly for individuals with reduced lower-limb strength and control. Since cognitive load can increase muscle recruitment to maintain balance, targeting these muscles in a controlled VR setting may enhance functional stability and improve performance of activities of daily living. Therefore, this study aimed to compare lower-limb muscle activation during single- and dual-task VR balance activities. Methods: Twenty-one healthy participants were recruited for this within-subject, repeated-measures study investigating the effect of task difficulty on lower-limb muscle activation during VR balance exercises. A non-immersive VR system developed by the Sensor Physiotherapy Intervention (SPIN) research group at Cardiff University was used to deliver two dynamic balance tasks: high-stepping and forward-stepping. Each task included three single-task and three dual-task difficulty levels. Surface electromyography (sEMG) recorded bilateral activation of the Gluteus Medius (GM), Biceps Femoris (BF), Rectus Femoris (RF), Lateral Gastrocnemius (LG) and Soleus (S) muscles. Mean sEMG amplitude was normalized to maximal voluntary isometric contraction (%MVIC). A two-way repeated-measures ANOVA was conducted to evaluate the main and interaction effects of task type and difficulty on muscle activation. Significant effects were further analysed using Bonferroni-adjusted post hoc pairwise comparisons. Results: There was a significant main effect of task difficulty (single- versus dual-task) on mean sEMG amplitude in the RF, LG and S muscles bilaterally (p≤0.05). Task type (high-stepping versus forward-stepping) also had a significant main effect on the right BF, right GM, and the RF, LG and S bilaterally (p≤0.05). A significant interaction between task difficulty and task type was observed for all muscles except the left BF (p≤0.05). Post-hoc Bonferroni-adjusted comparisons showed no significant differences between difficulty levels during high-stepping, but significantly higher activation under single-task conditions during forward-stepping in all muscles except the left BF. Conclusion(s): Lower-limb muscle activation during non-immersive SPIN VR balance tasks was significantly influenced by task difficulty, especially in the forward-stepping task. Interestingly, greater activation was observed during the single-task condition, suggesting that the absence of cognitive load may promote more robust muscular control strategies. Additionally, observed differences in mean sEMG amplitude between task types, along with significant interaction effects in all but one muscle, suggest that changes in muscle activation cannot be attributed to task difficulty alone. Impact: The SPIN VR system demonstrates potential as a rehabilitation tool for improving dual-task performance in individuals with reduced muscular control and postural stability. However, further research is needed to identify the specific VR tasks that most effectively challenge postural control and to optimise the integration of cognitive demands in order to enhance muscle activation during dual-task training.

Item Type:	Short Communication
Date Type:	Publication
Status:	Published
Schools:	Schools > Healthcare Sciences
Publisher:	Elsevier
ISSN:	0031-9406
Last Modified:	03 Aug 2026 11:30
URI:	https://orca.cardiff.ac.uk/id/eprint/188688

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