Comparative Analysis of Quadriceps Electromyography During Bodyweight Strength Exercises

Background: Although numerous exercises are prescribed for quadriceps femoris (QF) injury prevention and rehabilitation, few studies have compared QF muscle activation across commonly used bodyweight strength tasks. This study compared EMG activity of the rectus femoris proximal (RFP), rectus femoris medial (RFM), vastus lateralis (VL), and vastus medialis (VM) during seven bodyweight exercises with different stance positions. Methods: Twenty healthy male amateur football players performed three staggered-stance exercises (Split Squat, Bulgarian Split Squat, Backward Lunge), three parallel-stance exercises (Half-Squat, Russian Belt, Reverse Nordic), and one single-leg stance exercise (Lateral Step-Down). Surface EMG signals were recorded, and mean peak EMG values for each exercise were averaged and normalized to maximal isometric voluntary contraction (MVIC). Results: The highest VM and VL activation occurred during the Bulgarian Split Squat (VM: 85.4%; VL: 67.6% MVIC) and Backward Lunge (VM: 74.5%; VL: 59.9% MVIC). RFP and RFM showed the greatest activation during the Russian Belt (RFP: 49.8%; RFM: 39.6% MVIC) and Backward Lunge (RFP: 40.4%; RFM: 31.4% MVIC). VM and VL activation were significantly higher than RFP and RFM activation for all exercises except for Russian Belt and Reverse Nordic (p < 0.005). Conclusions: Exercises imposing greater knee stability demands preferentially activated VM and VL, whereas exercises with longer knee extensor lever arms maximized rectus femoris activation.