Document Detail

Increased musculoskeletal stiffness during load carriage at increasing walking speeds maintains constant vertical excursion of the body center of mass.
MedLine Citation:
PMID:  12600336     Owner:  NLM     Status:  MEDLINE    
The primary objective of this research was to determine changes in body and joint stiffness parameters and kinematics of the knee and body center of mass (COM), that result from wearing a backpack (BP) with a 40% body weight load at increasing speeds of walking. It was hypothesized that there would be speed and load-related increases in stiffness that would prevent significant deviations in the COM trajectory and in lower-extremity joint angles. Three independent biomechanical models employing kinematic data were used to estimate global lower-extremity stiffness, vertical stiffness and knee joint rotational stiffness in the sagittal plane during walking on a treadmill at speeds of 0.6-1.6 ms(-1) in 0.2 ms(-1) increments in BP and no backpack conditions. Kinematic data were collected using an Optotrak, three-dimensional motion analysis system. Knee angles and vertical excursion of the COM during the compression (loading phase) increased as a function of speed but not load. All three estimates of stiffness showed significant increases as a function of both speed and load. Significant interaction effects indicated a convergence of load-related stiffness values at lower speeds. Results suggested that increases in muscle-mediated stiffness are used to maintain a constant vertical excursion of the COM under load across the speeds tested, and thereby limit increases in metabolic cost that would occur if the COM would travel through greater vertical range of motion.
Kenneth G Holt; Robert C Wagenaar; Michael E LaFiandra; Masayoshi Kubo; John P Obusek
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Validation Studies    
Journal Detail:
Title:  Journal of biomechanics     Volume:  36     ISSN:  0021-9290     ISO Abbreviation:  J Biomech     Publication Date:  2003 Apr 
Date Detail:
Created Date:  2003-02-25     Completed Date:  2003-07-01     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  465-71     Citation Subset:  IM    
Department of Rehabilitation Sciences, Sargent College of Health and Rehabilitation Sciences, Boston University, 635 Commonwealth Avenue, Boston, MA 02215, USA.
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MeSH Terms
Computer Simulation
Knee Joint / physiology*
Models, Biological*
Posture / physiology
Reproducibility of Results
Sensitivity and Specificity
Stress, Mechanical
Walking / physiology*
Weight-Bearing / physiology*

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

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