Prostheses have enabled individuals with lower extremity amputation (ILEAs) to accomplish many daily activities. Prosthetic feet allow ILEA to locomote and improves their quality of life. Carbon-fiber running-specific prostheses (RSPs) with energy storing capabilities support ILEAs to perform sprinting by partly providing spring-like properties in their amputated legs. Previous studies declare the spring-like RSP behavior and stiffness regulation during ILEA sprinting using RSP, though little is known about the behavior of the whole system that is a complex combination of human body and prostheses. This paper models this combined system with human and prosthetic foot and RSP using the digital human technology, then, analyzes the ILEA walking using the prosthetic foot and sprinting using RSP. We develop models that are combinations of human and prostheses by individualizing a linkage structure and inertial parameters of the digital human model. Then, locomotion of ILEA is analyzed based on measurements with optical motion capture system and force plates, and kinematics and dynamics computation. This modeling and computational technique can be applied to the locomotion of ILEA as well as a human motion using tools, and expanded to an analysis and improvement of system involving human.