BIOMECHANICAL ANALYSIS OF THE LOWER EXTREMITY DURING MANUAL LIFTING ACTIVITIES

Abstract

Manual lifting activities involve lots of movement of the body and particularly the lower extremity. This study evaluated the biomechanical analysis of the human lower limb segments during manual lifting activities. The motion of the human lower limb in different cases is analysed, which provides a theoretical basis for motion dynamics. The lower limb segments are model as dynamic linkages with kinematics equations developed using inverse dynamics. Kinematic analysis of the human lower limb was done using the De Leva’s ratio and the Dempster’s Model. The hip, knee and foot segments were measured from the proximal end. Four (4) different positions were considered during manual lifting activities and the limbs on single and double supports. Kinematic analysis of the lower limb on double supports and single support indicated that the torques are highest at the hip joints at and lowest at the knee joint in flexion movement. The torques are 735.6 Nm and 13.69 Nm respectively. The angular accelerations are 3.28 rad/s, 6.21 rad/s, 7.46 rad/s for 58.65 kg, 77.82 kg and 93.18 kg respectively. This study concluded that more stresses are experienced when the lower limbs are not on double supports, that is, the two limbs on the ground or on the platform of support affirming that double-limb support helps to reduce the risk of tripping, falling and possible injuries to the body frame. It also helps in the total balance of the body frame. Similarly, for single supports, the leading leg performs negative work to redirect the center of mass velocity, while simultaneously, the trailing leg performs positive work to replace the lost energy. The trailing leg helps to balance the leading leg, hence, reducing the mechanical work done by the lower limb altogether.