Virtual Reality-Based Motor Imagery for Individuals With Low Imagery Ability: A Pilot Investigation of Isokinetic Strength and Electromyographic Activity

Motor imagery is a cognitive technique in which individuals mentally rehearse a movement without physically performing it. However, individuals with low imagery ability may not fully benefit from traditional motor imagery training. Virtual reality (VR) may enhance imagery vividness by providing immersive visual feedback. The purpose of this study is to compare the effects of immersive VR-based motor imagery, action observation combined with motor imagery, kinesthetic motor imagery alone, and a control condition on imagery ability, muscle strength, and muscle activation. Thirty-two healthy male participants will be assigned to one of four parallel groups based on imagery ability levels. All participants will complete a 4-week unilateral leg extension resistance training program (three sessions per week at 80% of one-repetition maximum). During each session, participants will perform their assigned imagery protocol. Primary outcomes include changes in imagery ability assessed by the Movement Imagery Questionnaire-3. Secondary outcomes include isokinetic quadriceps peak torque, average power, and surface electromyography activity of the rectus femoris, vastus medialis, and vastus lateralis muscles. The findings of this study may provide insight into whether immersive VR can enhance the effectiveness of motor imagery training in individuals with low imagery ability.

Motor imagery training has been shown to enhance motor performance and strength adaptations; however, its effectiveness is strongly influenced by individual imagery ability. Individuals with low imagery ability may experience limited benefits due to reduced vividness and sensory engagement during mental rehearsal. Immersive virtual reality (VR) may enhance the perceptual and sensory components of imagery by providing first-person visual feedback, thereby potentially improving motor-related neural activation and training adaptations. This study is designed as a 4-week, parallel-group interventional trial including healthy young adult males. Participants will be categorized according to imagery ability assessed by the Movement Imagery Questionnaire-3 (MIQ-3) and allocated into four groups: immersive VR-based motor imagery, action observation combined with motor imagery, kinesthetic motor imagery alone, and a control condition involving relaxation imagery. All participants will complete a supervised unilateral leg extension resistance training program performed three times per week at 80% of one-repetition maximum. Each session will consist of four sets of 8-12 repetitions for the dominant leg. Imagery interventions will be administered prior to each training session according to group assignment. Isokinetic strength assessments will be performed at angular velocities of 60°/s and 120°/s. Surface electromyography (sEMG) signals will be recorded from the rectus femoris, vastus medialis, and vastus lateralis muscles during testing. Imagery ability will be reassessed following the intervention period. The primary objective of the study is to determine whether immersive VR-based motor imagery enhances imagery ability and neuromuscular adaptations compared to traditional motor imagery approaches and control conditions.