Amputee gait produces periodic occlusion of residual limb blood vessels. During the stance phase of gait, body weight cause the prosthesis to compresses the soft tissue of the residual limb and occlude blood flow. This occlusion can be relieved during swing phase, but may depend on type of prosthesis. The purpose of the proposed research is to: (1) discover the range of tissue oxygenation in the intact and residual lower limbs of dysvascular amputees during gait and (2) to learn which of five different prosthetic limb systems provides greater tissue oxygenation.