This subject was 48 yr old and had his amputation 24 yr prior as a result of traumatic injury. His 19 cm length residual limb was conical in shape with a fair amount of hair and very little soft tissue. He was 188 cm in height and 80 kg in mass. A K-4 level ambulator, this subject was healthy, did not take medications, and used his prosthesis for at least 12 h/day. He regularly used a PTB endoskeletal prosthesis, a flexible socket liner with a gel liner, a lock-and-pin suspension, and a Freedom Innovations dynamic response prosthetic foot. He had a history of ingrown hairs/blisters that formed when his prosthesis pistoned excessively as a result of limb volume changes. His limb typically changed volume after high activity. He was a good candidate for elevated vacuum because of his high activity, mechanical aptitude, need for superior suspension, and desire to not add socks throughout the day to compensate for volume fluctuations. Prior to bioimpedance testing he was fitted with a new socket equipped with a P2 Harmony vacuum unit, and Seattle Lightfoot (TrueLife). He used this prosthesis exclusively for the 3 wk prior to bioimpedance testing.