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Changes in timing of muscle contractions and running economy with altered stride pattern during running.
MedLine Citation:
PMID:  23948332     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Large alterations to the preferred running stride decrease running economy, and shorter strides increase leg muscle activity. However, the effect of altered strides on the timing of leg muscle activation is not known. The aim of this study was to evaluate the impact of moderate alterations to the running stride on running economy and the timing of biceps femoris (BF), vastus lateralis (VL) and gastrocnemius (GAST) muscle contractions. The preferred stride pattern for eleven trained male runners was measured prior to a separate visit where participants ran for bouts of 5min whilst synchronising foot contacts to a metronome signal which was tuned to (1) the preferred stride, and (2) frequencies which related to ±8% and ±4% of the preferred stride length. Running economy was measured at each stride pattern along with electromyography and three-dimensional kinematics to estimate onset and offset of muscle contractions for each muscle. Running economy was greatest at the preferred stride length. However, a quadratic fit to the data was optimised at a stride which was 2.9% shorter than preferred. Onset and offset of BF and VL muscle contractions occurred earlier with shorter than preferred strides. We detected no changes to the timing of muscle contractions with longer than preferred strides and no changes to GAST muscle contractions. The results suggest that runners optimise running economy with a stride length that is close to, but shorter than, the preferred stride, and that timing of BF and VL muscle contractions change with shorter than preferred strides.
Authors:
Mark J Connick; Francois-Xavier Li
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-8-12
Journal Detail:
Title:  Gait & posture     Volume:  -     ISSN:  1879-2219     ISO Abbreviation:  Gait Posture     Publication Date:  2013 Aug 
Date Detail:
Created Date:  2013-8-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9416830     Medline TA:  Gait Posture     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2013 Elsevier B.V. All rights reserved.
Affiliation:
School of Human Movement Studies, University of Queensland, Brisbane, Australia. Electronic address: m.connick@uq.edu.au.
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