Document Detail

How do infants adapt to loading of the limb during the swing phase of stepping?
MedLine Citation:
PMID:  12611979     Owner:  NLM     Status:  MEDLINE    
Previous results from this laboratory have shown that human infants (<12 mo old) respond appropriately to transient changes in sensory input during stepping. We examined how infants adapted to a more enduring change in sensory input by applying load to one limb during stepping. A small weight (500-900 g) was strapped around the lower leg of infants aged 3-11 mo. Stepping with the weight on was recorded on the treadmill for a period of 0.5-3 min. The weight was then quickly detached during stepping, and the immediate response to unexpected loss of the weight recorded. Three-segment dynamic analysis of leg motion was used to estimate hip, knee, and ankle torques during swing in the sagittal plane. All infants adapted to the additional load on the leg by immediately increasing the generation of hip and knee flexor muscle torques. When the weight was removed, 7 of the 22 infants tested exhibited an after-effect (high stepping) in the first step after removal of the weight. The after-effect was manifested as an increase in toe trajectory height and hip flexion and coincided with higher hip flexor muscle torque in early swing. In an additional series of control experiments using seven infants, after-effects were shown to be unrelated to a sudden change in cutaneous input with removal of the weight. The presence of an after-effect indicates that some infants made an enduring adaptation to their stepping pattern that is revealed with the unexpected removal of the weight.
Tania Lam; Claire Wolstenholme; Jaynie F Yang
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2002-12-11
Journal Detail:
Title:  Journal of neurophysiology     Volume:  89     ISSN:  0022-3077     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2003 Apr 
Date Detail:
Created Date:  2003-04-10     Completed Date:  2003-05-29     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1920-8     Citation Subset:  IM    
University Centre for Neuroscience and Department of Physical Therapy, University of Alberta, Edmonton, Alberta T6G 2G4, Canada.
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MeSH Terms
Adaptation, Physiological / physiology*
Gait / physiology*
Hip Joint / physiology
Knee Joint / physiology
Leg / physiology*
Muscle, Skeletal / physiology
Walking / physiology
Weight-Bearing / physiology

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