Document Detail


The effect of reduced gravity on the kinematics of human walking: a test of the dynamic similarity hypothesis for locomotion.
MedLine Citation:
PMID:  9364025     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
To gain insight into the basic principles that govern the biomechanics of locomotion, we investigated the effect of reduced gravity on walking kinematics. We hypothesized that humans walk in a dynamically similar fashion at combinations of speed and simulated gravity that provide equal values of the Froude number, v2/gLleg, where v is forward speed, g is gravitational acceleration and Lleg is leg length. The Froude number has been used to predict the kinematics and kinetics of legged locomotion over a wide range of animal sizes and speeds, and thus provides a potentially unifying theory for the combined effects of speed, size and gravity on locomotion biomechanics. The occurrence of dynamic similarity at equal Froude numbers has been attributed previously to the importance of gravitational forces in determining locomotion mechanics. We simulated reduced gravity using a device that applies a nearly constant upward force to the torso while subjects walked on a treadmill. We found that at equal Froude numbers, under different levels of gravity (0.25g-1.0g), the subjects walked with nearly the same duty factor (ratio of contact time to stride time), but with relative stride lengths (Ls/Lleg, where Ls is stride length) that differed by as much as 67 %, resulting in the rejection of our hypothesis. To understand the separate effects of speed and gravity further, we compared the mechanics of walking at the same absolute speed at different levels of gravity (0.25g-1.0g). In lower gravity, subjects walked with lower duty factors (10 %) and shorter relative stride lengths (16 %). These modest changes in response to the fourfold change in gravity indicate that factors other than gravitational forces are the primary determinants of walking biomechanics.
Authors:
J M Donelan; R Kram
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  200     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  1997 Dec 
Date Detail:
Created Date:  1998-01-27     Completed Date:  1998-01-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  3193-201     Citation Subset:  IM; S    
Affiliation:
Integrative Biology Department, University of California, Berkeley, CA 94720-3140, USA.
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MeSH Terms
Descriptor/Qualifier:
Biomechanics
Gravitation*
Humans
Walking / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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