Document Detail

Effects of stride length and running mileage on a probabilistic stress fracture model.
MedLine Citation:
PMID:  19915501     Owner:  NLM     Status:  MEDLINE    
The fatigue life of bone is inversely related to strain magnitude. Decreasing stride length is a potential mechanism of strain reduction during running. If stride length is decreased, the number of loading cycles will increase for a given mileage. It is unclear if increased loading cycles are detrimental to skeletal health despite reductions in strain. PURPOSE: To determine the effects of stride length and running mileage on the probability of tibial stress fracture. METHODS: Ten male subjects ran overground at their preferred running velocity during two conditions: preferred stride length and 10% reduction in preferred stride length. Force platform and kinematic data were collected concurrently. A combination of experimental and musculoskeletal modeling techniques was used to determine joint contact forces acting on the distal tibia. Peak instantaneous joint contact forces served as inputs to a finite element model to estimate tibial strains during stance. Stress fracture probability for stride length conditions and three running mileages (3, 5, and 7 miles x d(-1)) were determined using a probabilistic model of bone damage, repair, and adaptation. Differences in stress fracture probability were compared between conditions using a 2 x 3 repeated-measures ANOVA. RESULTS: The main effects of stride length (P = 0.017) and running mileage (P = 0.001) were significant. Reducing stride length decreased the probability of stress fracture by 3% to 6%. Increasing running mileage increased the probability of stress fracture by 4% to 10%. CONCLUSIONS: Results suggest that strain magnitude plays a more important role in stress fracture development than the total number of loading cycles. Runners wishing to decrease their probability for tibial stress fracture may benefit from a 10% reduction in stride length.
W Brent Edwards; David Taylor; Thomas J Rudolphi; Jason C Gillette; Timothy R Derrick
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  41     ISSN:  1530-0315     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2009 Dec 
Date Detail:
Created Date:  2009-11-20     Completed Date:  2010-02-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2177-84     Citation Subset:  IM; S    
Department of Kinesiology, Iowa State University, Ames, IA 50011-1160, USA.
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MeSH Terms
Cumulative Trauma Disorders
Fractures, Stress / etiology,  physiopathology,  prevention & control*
Gait / physiology*
Models, Statistical
Muscle, Skeletal
Running / physiology*
Tibia / injuries
Young Adult

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

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