Dynamic stability of running: The effects of speed and leg amputations on the maximal Lyapunov exponent

In this paper, we study dynamic stability during running, focusing on the effects of speed, and the use of a leg prosthesis. We compute and compare the maximal Lyapunov exponents of kinematic time-series data from subjects with and without unilateral transtibial amputations running at a wide range o...

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Bibliographic Details
Published in:Chaos (Woodbury, N.Y.) N.Y.), 2013-12, Vol.23 (4), p.043131-043131
Main Authors: Look, Nicole, Arellano, Christopher J., Grabowski, Alena M., McDermott, William J., Kram, Rodger, Bradley, Elizabeth
Format: Article
Language:English
Subjects:
Amputation
ASYMMETRY
Center of mass
CENTER-OF-MASS SYSTEM
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
COMPARATIVE EVALUATIONS
Control stability
Dynamic stability
Dynamics
Economic models
INSTABILITY
Legs
Liapunov exponents
LYAPUNOV METHOD
Prostheses
Running
STABILITY
VELOCITY
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Summary:In this paper, we study dynamic stability during running, focusing on the effects of speed, and the use of a leg prosthesis. We compute and compare the maximal Lyapunov exponents of kinematic time-series data from subjects with and without unilateral transtibial amputations running at a wide range of speeds. We find that the dynamics of the affected leg with the running-specific prosthesis are less stable than the dynamics of the unaffected leg and also less stable than the biological legs of the non-amputee runners. Surprisingly, we find that the center-of-mass dynamics of runners with two intact biological legs are slightly less stable than those of runners with amputations. Our results suggest that while leg asymmetries may be associated with instability, runners may compensate for this effect by increased control of their center-of-mass dynamics.
ISSN:1054-1500
1089-7682
DOI:10.1063/1.4837095