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Influence of intrinsic and extrinsic determinants on the transition from walking to running

Philippe Malcolm UGent (2010)
abstract
Introduction: Experiments on treadmill showed that humans spontaneously switch from walking to running around a speed of 2 m s-1 although they are able to walk faster or run slower. Different factors that could influence the walk-to-run transition (WRT) speed, called determinants, have been proposed. The aim of this work was to describe and experimentally validate the role of one type of intrinsic determinant and one extrinsic determinant (i.e. respectively ankle muscular effort and optic flow). Methods: Ultrasonography was used to describe muscle-tendon behavior of a muscle that potentially determines the walk-to-run transition i.e. m. gastrocnemius. In order to experimentally test the influence of muscular effort of the plantarflexors and dorsiflexors on the WRT speed a powered ankle-foot exoskeleton was developed and its effect on metabolic cost was tested. In order to understand how the WRT is initiated in ecological overground conditions a hallway was constructed that allowed manipulating optic flow. Results and discussion: The ultrasound measurements showed an abrupt change in m. gastrocnemius muscle-tendon behavior during the WRT that possibly contributes to power the energy jump during the WRT step. Each of the bi-directional experimental manipulations (plantarflexors, dorsiflexors and optic flow) was able to provoke a decrease in walk-to-run transition speed but no increase. The decreases prove that the studied parameters are indeed determinants. The absence of increases could be explained by weak links in the pool of determinants that prevent an increase in the walk-to-run transition speed, the focused nature of the experimental manipulations and the protocols that were used. The combined results suggest that the walk-to-run transition is determined by multiple determinants whose hierarchical position depends on context and protocol. The powered exoskeleton that was used was shown to be able to increase the economy of normal walking when its actuation coincided with push off but it could not decrease m. gastrocnemius activation. Nevertheless, it proved to be a useful tool for fundamental locomotion research.
Please use this url to cite or link to this publication:
author
promoter
UGent
organization
year
type
dissertation (monograph)
subject
keyword
walking, optic flow, locomotion, transition, biorobotics, gait, running, exoskeleton
pages
136 pages
publisher
Ghent University. Faculty of Medicine and Health Sciences
place of publication
Ghent, Belgium
defense location
Gent : HILO-GUSB (auditorium A)
defense date
2010-09-20 17:30
language
English
UGent publication?
yes
classification
D1
additional info
dissertation consists of copyrighted materials
copyright statement
I have transferred the copyright for this publication to the publisher
id
1047392
handle
http://hdl.handle.net/1854/LU-1047392
date created
2010-09-29 16:41:41
date last changed
2010-12-10 15:45:45
@phdthesis{1047392,
  abstract     = {Introduction: Experiments on treadmill showed that humans spontaneously switch from walking to running around a speed of 2 m s-1 although they are able to walk faster or run slower. Different factors that could influence the walk-to-run transition (WRT) speed, called determinants, have been proposed. The aim of this work was to describe and experimentally validate the role of one type of intrinsic determinant and one extrinsic determinant (i.e. respectively ankle muscular effort and optic flow).
Methods: Ultrasonography was used to describe muscle-tendon behavior of a muscle that potentially determines the walk-to-run transition i.e. m. gastrocnemius.
In order to experimentally test the influence of muscular effort of the plantarflexors and dorsiflexors on the WRT speed a powered ankle-foot exoskeleton was developed and its effect on metabolic cost was tested.
In order to understand how the WRT is initiated in ecological overground conditions a hallway was constructed that allowed manipulating optic flow.
Results and discussion: The ultrasound measurements showed an abrupt change in m. gastrocnemius muscle-tendon behavior during the WRT that possibly contributes to power the energy jump during the WRT step. Each of the bi-directional experimental manipulations (plantarflexors, dorsiflexors and optic flow) was able to provoke a decrease in walk-to-run transition speed but no increase. The decreases prove that the studied parameters are indeed determinants. The absence of increases could be explained by weak links in the pool of determinants that prevent an increase in the walk-to-run transition speed, the focused nature of the experimental manipulations and the protocols that were used. The combined results suggest that the walk-to-run transition is determined by multiple determinants whose hierarchical position depends on context and protocol. The powered exoskeleton that was used was shown to be able to increase the economy of normal walking when its actuation coincided with push off but it could not decrease m. gastrocnemius activation. Nevertheless, it proved to be a useful tool for fundamental locomotion research.},
  author       = {Malcolm, Philippe},
  keyword      = {walking,optic flow,locomotion,transition,biorobotics,gait,running,exoskeleton},
  language     = {eng},
  pages        = {136},
  publisher    = {Ghent University. Faculty of Medicine and Health Sciences},
  school       = {Ghent University},
  title        = {Influence of intrinsic and extrinsic determinants on the transition from walking to running},
  year         = {2010},
}

Chicago
Malcolm, Philippe. 2010. “Influence of Intrinsic and Extrinsic Determinants on the Transition from Walking to Running”. Ghent, Belgium: Ghent University. Faculty of Medicine and Health Sciences.
APA
Malcolm, P. (2010). Influence of intrinsic and extrinsic determinants on the transition from walking to running. Ghent University. Faculty of Medicine and Health Sciences, Ghent, Belgium.
Vancouver
1.
Malcolm P. Influence of intrinsic and extrinsic determinants on the transition from walking to running. [Ghent, Belgium]: Ghent University. Faculty of Medicine and Health Sciences; 2010.
MLA
Malcolm, Philippe. “Influence of Intrinsic and Extrinsic Determinants on the Transition from Walking to Running.” 2010 : n. pag. Print.