Effect of movement variation on lower limb muscle activity and joint torque during squat

Abstract

The purpose of this study was to compare hip and knee joint extension torque and the activity of eight muscles around the hip and knee joints during three squat exercises with different movements. Ten male athletes performed three different squats (Normal squat : NS, Knee push squat : KPS, Hip drive squat : HDS). KPS is the type of squat which emphasizes knee joint movement without moving the hip joint position back and forth. On the other hand, HDS is the type of squat which emphasizes hip joint movement, while keeping the knee joint position fixed. Kinematic and kinetic variables such as angle, angular velocity, net torque and power of the joints of the lower extremity were calculated during the descending and ascending phase of each squat. At the same time, surface electrodes were placed on eight muscles of the lower extremity, and %iEMG was also calculated during the same phases. During the descending phase, Elector spinae muscle activity and hip joint extension torque was significantly greater for HDS than KPS. Rectus femoris and Vastus lateralis muscle activity was significantly greater for KPS than HDS. In addition, KPS showed significantly greater knee joint extension torque than HDS and NS. At the ascending phase, Elector spinae, Glueus maximus and Biceps femoris muscle activity, and hip joint extension torque was significantly greater for HDS than KPS and NS. Rectus femoris muscle activity and knee joint extension torque was significantly greater for KPS than HDS and NS. These results suggest that HDS is effective for selectively training the hip extensor, and KPS is effective for training the Rectus femoris muscle.