FIGURE 1.

Human bipedal musculoskeletal model used in the study showing the joints. Single degree-of-freedom revolute joints connected each foot to the talus to define the subtalar joints; the talus to the tibia/fibula to define the ankle joints, and the tibia/fibula to the femur to define the knee joints. Three degrees-of-freedom gimbal joints connected the two femurs to the pelvis to define flexion/extension, adduction/abduction and internal/external rotation of the hip joints. The torso attaches to the pelvis via a three degree-of-freedom gimbal joint that defined trunk flexion/extension (pitch), lateral bending (roll) and axial rotation (yaw). Five other lumbar joints also had three degrees-of-freedom each but moved synergistically in accordance with anatomically realistic kinematic constraints with respect to the torso-pelvic joint (White and Panjabi, 1990; Wilkenfeld et al., 2006). All other joints are prescribed to have zero velocity and acceleration; but were invaluable in defining realistic muscle wrapping points.