What is the Optimal Stiffness and Height of a Running-specific Prosthesis?

The proposed study aims to characterize the effects of running-specific leg prosthetic stiffness and height during on performance during running and sprinting to optimize running-specific prosthesis prescription. The investigators will collect biomechanical and metabolic data from participants with unilateral and bilateral below the knee amputations while they run at different speeds on a treadmill. This data will be used to understand the effects of running prostheses. Then, these parameters will be used to develop prosthetic prescription techniques for people with below the knee amputations.

10 athletes with a unilateral and 5 athletes with bilateral transtibial amputations used 15 different running-specific prosthetic configurations while they ran at one speed and we measured metabolic rates and biomechanics. 10 athletes with a unilateral and 5 athletes with bilateral transtibial amputations used 15 different running-specific prosthetic configurations while they ran at multiple speeds and we measured top speeds and biomechanics.

Participants will run on an instrumented treadmill at a range of speeds from a jogging speed up to top speed.

Participants will run using the Otto Bock prosthesis at a recommended stiffness and height, one category stiffer than recommended at the recommended height, one category softter than recommended at the recommended height, at the optimal stiffness and 2 cm taller, and at the optimal stiffness and 2 cm shorter.

Participants will run using the Ossur prosthesis at a recommended stiffness and height, one category stiffer than recommended at the recommended height, one category softter than recommended at the recommended height, at the optimal stiffness and 2 cm taller, and at the optimal stiffness and 2 cm shorter.

Participants will run using the Freedom Innovations prosthesis at a recommended stiffness and height, one category stiffer than recommended at the recommended height, one category softter than recommended at the recommended height, at the optimal stiffness and 2 cm taller, and at the optimal stiffness and 2 cm shorter.

The investigators will measure stance average vertical ground reaction forces during running and sprinting.

The investigators will measure rates of oxygen consumption and carbon dioxide production during running to determine the optimal prosthesis for each participant.

The investigators will measure the top sprinting speed to determine the optimal prosthesis for each participant.

Inclusion Criteria: bilateral or unilateral transtibial amputation at least one year of running experience using running-specific prostheses 18-55 years old no current problems with their prosthesis or residual limb at a K4 Medicare Functional Classification Level Exclusion Criteria: Cardiovascular, pulmonary, or neurological disease or disorder