Document Detail


Dynamics of the in-run in ski jumping: a simulation study.
MedLine Citation:
PMID:  16260845     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A ski jumper tries to maintain an aerodynamic position in the in-run during changing environmental forces. The purpose of this study was to analyze the mechanical demands on a ski jumper taking the in-run in a static position. We simulated the in-run in ski jumping with a 4-segment forward dynamic model (foot, leg, thigh, and upper body). The curved path of the in-run was used as kinematic constraint, and drag, lift, and snow friction were incorporated. Drag and snow friction created a forward rotating moment that had to be counteracted by a plantar flexion moment and caused the line of action of the normal force to pass anteriorly to the center of mass continuously. The normal force increased from 0.88 G on the first straight to 1.65 G in the curve. The required knee joint moment increased more because of an altered center of pressure. During the transition from the straight to the curve there was a rapid forward shift of the center of pressure under the foot, reflecting a short but high angular acceleration. Because unrealistically high rates of change of moment are required, an athlete cannot do this without changing body configuration which reduces the required rate of moment changes.
Authors:
Gertjan J C Ettema; Steinar Bråten; Maarten F Bobbert
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied biomechanics     Volume:  21     ISSN:  1065-8483     ISO Abbreviation:  J Appl Biomech     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-11-01     Completed Date:  2005-11-15     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9315240     Medline TA:  J Appl Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  247-59     Citation Subset:  IM    
Affiliation:
Human Movement of Sciences Program, Faculty of Social Sciences and Technology Management, Norwegian University of Science and Technology, Trondheim, Norway.
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MeSH Terms
Descriptor/Qualifier:
Friction
Humans
Knee / physiology*
Models, Theoretical
Movement
Physical Phenomena
Physics
Pressure
Skiing / physiology*
Snow

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


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