Document Detail

Applied horizontal force increases impact loading in reduced-gravity running.
MedLine Citation:
PMID:  11311709     Owner:  NLM     Status:  MEDLINE    
The chronic exposure of astronauts to microgravity results in structural degradation of their lower limb bones. Currently, no effective exercise countermeasure exists. On Earth, the impact loading that occurs with regular locomotion is associated with the maintenance of bone's structural integrity, but impact loads are rarely experienced in space. Accurately mimicking Earth-like impact loads in a reduced-gravity environment should help to reduce the degradation of bone caused by weightlessness. We previously showed that running with externally applied horizontal forces (AHF) in the anterior direction qualitatively simulates the high-impact loading associated with downhill running on Earth. We hypothesized that running with AHF at simulated reduced gravity would produce impact loads equal to or greater than values experienced during normal running at Earth gravity. With an AHF of 20% of gravity-specific body weight at all gravity levels, impact force peaks increased 74%, average impact loading rates increased 46%, and maximum impact loading rates increased 89% compared to running without any AHF. In contrast, AHF did not substantially affect active force peaks. Duty factor and stride frequency decreased modestly with AHF at all gravity levels. We found that running with an AHF in simulated reduced gravity produced impact loads equal to or greater than those experienced at Earth gravity. An appropriate AHF could easily augment existing partial gravity treadmill running exercise countermeasures used during spaceflight and help prevent musculoskeletal degradation.
Y H Chang; C M Hamerski; R Kram
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biomechanics     Volume:  34     ISSN:  0021-9290     ISO Abbreviation:  J Biomech     Publication Date:  2001 May 
Date Detail:
Created Date:  2001-04-20     Completed Date:  2001-07-26     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  679-85     Citation Subset:  IM; S    
Locomotion Laboratory, Department of Integrative Biology, University of California, Berkeley, CA 94720-3140, USA.
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MeSH Terms
Bone Resorption / etiology,  prevention & control
Bone and Bones / physiology
Running / physiology*
Space Flight
Weightlessness Countermeasures*
Weightlessness Simulation*

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

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