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.