Background: Intrepid Dynamic Exoskeletal Orthoses (IDEO) and Running-Specific Prostheses (RSPs) have been designed to allow people with lower extremity limb salvage (LS) and transtibial amputations (TTA) to more effectively run, an activity used to improve fitness and health, and to assess physical endurance in military populations. Exercise such as running is extremely important for and strongly associated with quality of life. Moreover, compared to use of conventional orthoses and prostheses, use of IDEOs and RSPs has resulted in significantly higher functional ability and quality of life for service members with LS and TTA. However, existing practices use a trial-and-error approach for prescription based on a male cohort and do not necessarily optimize performance and satisfaction for women service members. Our goals are to determine the optimal IDEO and RSP components and develop quantitative guidelines for prescribing orthoses and prostheses for running in women service members with LS and TTA so that these women can regain the greatest possible level of functional ability and return to an active lifestyle and/or active duty. Objective/Hypothesis: To determine the physiological and biomechanical effects of using different IDEO and RSP stiffness and weight in women service members with LS or TTA, which will maximize recovery, restore function, and improve quality of life for women with LS or TTA. Specific Aims (SA)/Hypotheses (Hyp): SA1. Verify inter- and intra-session reliability of the Naval Medical Center San Diego Gait Analysis/Biomechanics Laboratory and VA Applied Biomechanics Lab. Hyp 1. Repeatability between sites will be strong as measured by an interclass correlation coefficient (ICC) > 0.90, and minimal detectable changes (MDCs) in kinematics, kinetics and metabolic costs comparable to prior work in non-amputees (Wilken et al., 2012).