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Title: 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 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.
Authors:
 [1] ; ; ;  [2] ;  [3] ;  [4]
  1. Department of Applied Mathematics, University of Colorado Boulder, Boulder, Colorado 80309 (United States)
  2. Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado 80309 (United States)
  3. The Orthopedic Specialty Hospital, Murray, Utah 84107 (United States)
  4. Department of Computer Science, University of Colorado Boulder, Boulder, Colorado 80309, USA and Santa Fe Institute, Santa Fe, New Mexico 87501 (United States)
Publication Date:
OSTI Identifier:
22251753
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chaos (Woodbury, N. Y.); Journal Volume: 23; Journal Issue: 4; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ASYMMETRY; CENTER-OF-MASS SYSTEM; COMPARATIVE EVALUATIONS; INSTABILITY; LYAPUNOV METHOD; STABILITY; VELOCITY