While exercising, an athlete holds a position with a 90-degree hip flexion and 90-degree knee flexion. Considering only the iliopsoas muscle group, determine the force necessary to maintain this position given the moment arm of the iliopsoas is 10.5 cm from the hip joint, the mass of the thigh (6.83 kg), the moment arm for the center of mass for the thigh (13 cm), the mass of the lower leg (4.17 kg), and the moment arm for the center of mass for the lower leg (40 cm from the hip joint).