Document Detail

Leg stiffness adjustment for a range of hopping frequencies in humans.
MedLine Citation:
PMID:  19879582     Owner:  NLM     Status:  MEDLINE    
The purpose of the present study was to determine how humans adjust leg stiffness over a range of hopping frequencies. Ten male subjects performed in place hopping on two legs, at three frequencies (1.5, 2.2, and 3.0Hz). Leg stiffness, joint stiffness and touchdown joint angles were calculated from kinetic and/or kinematics data. Electromyographic activity (EMG) was recorded from six leg muscles. Leg stiffness increased with an increase in hopping frequency. Hip and knee stiffnesses were significantly greater at 3.0Hz than at 1.5Hz. There was no significant difference in ankle stiffness among the three hopping frequencies. Although there were significant differences in EMG activity among the three hopping frequencies, the largest was the 1.5Hz, followed by the 2.2Hz and then 3.0Hz. The subjects landed with a straighter leg (both hip and knee were extended more) with increased hopping frequency. These results suggest that over the range of hopping frequencies we evaluated, humans adjust leg stiffness by altering hip and knee stiffness. This is accomplished by extending the touchdown joint angles rather than by altering neural activity.
Hiroaki Hobara; Koh Inoue; Tetsuro Muraoka; Kohei Omuro; Masanori Sakamoto; Kazuyuki Kanosue
Publication Detail:
Type:  Journal Article     Date:  2009-10-30
Journal Detail:
Title:  Journal of biomechanics     Volume:  43     ISSN:  1873-2380     ISO Abbreviation:  J Biomech     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-28     Completed Date:  2010-04-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  506-11     Citation Subset:  IM    
Copyright Information:
Copyright 2009 Elsevier Ltd. All rights reserved.
Department of Rehabilitation for the Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, Tokorozawa, Saitama, Japan.
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MeSH Terms
Adaptation, Physiological / physiology
Computer Simulation
Elastic Modulus / physiology
Gait / physiology*
Leg / physiology*
Models, Biological*
Oscillometry / methods
Physical Exertion / physiology*
Young Adult

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