Prosthetic model, but not stiffness or height, affects the metabolic cost of running for athletes with unilateral transtibial amputations
- 1 July 2017
- journal article
- research article
- Published by American Physiological Society in Journal of Applied Physiology
- Vol. 123 (1), 38-48
- https://doi.org/10.1152/japplphysiol.00896.2016
Abstract
Running-specific prostheses enable athletes with lower limb amputations to run by emulating the spring-like function of biological legs. Current prosthetic stiffness and height recommendations aim to mitigate kinematic asymmetries for athletes with unilateral transtibial amputations. However, it is unclear how different prosthetic configurations influence the biomechanics and metabolic cost of running. Consequently, we investigated how prosthetic model, stiffness, and height affect the biomechanics and metabolic cost of running. Ten athletes with unilateral transtibial amputations each performed 15 running trials at 2.5 or 3.0 m/s while we measured ground reaction forces and metabolic rates. Athletes ran using three different prosthetic models with five different stiffness category and height combinations per model. Use of an Ottobock 1E90 Sprinter prosthesis reduced metabolic cost by 4.3 and 3.4% compared with use of Freedom Innovations Catapult [fixed effect (β) = −0.177; P < 0.001] and Össur Flex-Run (β = −0.139; P = 0.002) prostheses, respectively. Neither prosthetic stiffness (P ≥ 0.180) nor height (P = 0.062) affected the metabolic cost of running. The metabolic cost of running was related to lower peak (β = 0.649; P = 0.001) and stance average (β = 0.772; P = 0.018) vertical ground reaction forces, prolonged ground contact times (β = −4.349; P = 0.012), and decreased leg stiffness (β = 0.071; P < 0.001) averaged from both legs. Metabolic cost was reduced with more symmetric peak vertical ground reaction forces (β = 0.007; P = 0.003) but was unrelated to stride kinematic symmetry (P ≥ 0.636). Therefore, prosthetic recommendations based on symmetric stride kinematics do not necessarily minimize the metabolic cost of running. Instead, an optimal prosthetic model, which improves overall biomechanics, minimizes the metabolic cost of running for athletes with unilateral transtibial amputations. NEW & NOTEWORTHY The metabolic cost of running for athletes with unilateral transtibial amputations depends on prosthetic model and is associated with lower peak and stance average vertical ground reaction forces, longer contact times, and reduced leg stiffness. Metabolic cost is unrelated to prosthetic stiffness, height, and stride kinematic symmetry. Unlike nonamputees who decrease leg stiffness with increased in-series surface stiffness, biological limb stiffness for athletes with unilateral transtibial amputations is positively correlated with increased in-series (prosthetic) stiffness.Keywords
Funding Information
- U.S. Department of Defense (DOD) (W81XWH-11-2-0222)
This publication has 63 references indexed in Scilit:
- Amputee Locomotion: Determining the Inertial Properties of Running-Specific ProsthesesArchives of Physical Medicine and Rehabilitation, 2013
- Amputee locomotion: Spring-like leg behavior and stiffness regulation using running-specific prosthesesJournal of Biomechanics, 2013
- Anatomically Asymmetrical Runners Move More Asymmetrically at the Same Metabolic CostPLOS ONE, 2013
- Bionic ankle–foot prosthesis normalizes walking gait for persons with leg amputationProceedings. Biological sciences, 2011
- Running Stride Peak Forces Inversely Determine Running Economy in Elite RunnersJournal of Strength & Conditioning Research, 2011
- Running-specific prostheses limit ground-force during sprintingBiology Letters, 2009
- Leg stiffness and stride frequency in human runningJournal of Biomechanics, 1996
- The spring-mass model for running and hoppingJournal of Biomechanics, 1989
- Mechanical properties of various mammalian tendonsJournal of Zoology, 1986
- Energetic Aspects of Skeletal Muscle ContractionExercise and Sport Sciences Reviews, 1985