Document Detail

Normalization of ground reaction forces.
MedLine Citation:
PMID:  17215554     Owner:  NLM     Status:  MEDLINE    
The appropriateness of normalizing data, as one method to reduce the effects of a covariate on a dependent variable, should be evaluated. Using ratio, 0.67-nonlinear, and fitted normalizations, the aim of this study was to investigate the relationship between ground reaction force variables and body mass (BM). Ground reaction forces were recorded for 40 female subjects running at 3.7 +/- 0.18 m x s(-1) (mass = 58 +/- 6 kg). The explained variance for mass to forces (peak-impact-vertical = 70%; propulsive-vertical = 27%; braking = 40%) was reduced to <0.1% for mass to ratio normalized forces (i.e., forces/BM1) with statistically significantly different power exponents (p < 0.05). The smaller covariate effect of mass on loading rate variables of 2-16% was better removed through fitted normalization (e.g., vertical-instantaneous-loading rate/ BM(0.69+/-0.93); +/-95% CI) with nonlinear power exponents ranging from 0.51 to 1.13. Generally, these were similar to 0.67 as predicted through dimensionality theory, but, owing to the large confidence intervals, these power exponents were not statistically significantly different from absolute or ratio normalized data (p > 0.05). Further work is warranted to identify the appropriate method to normalize loading rates either to mass or to another covariate. Ratio normalization of forces to mass, as predicted through Newtonian mechanics, is recommended for comparing subjects of different masses.
David R Mullineaux; Clare E Milner; Irene S Davis; Joseph Hamill
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of applied biomechanics     Volume:  22     ISSN:  1065-8483     ISO Abbreviation:  J Appl Biomech     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2007-01-11     Completed Date:  2007-02-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9315240     Medline TA:  J Appl Biomech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  230-3     Citation Subset:  IM    
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MeSH Terms
Anthropometry / methods*
Body Weight / physiology*
Computer Simulation
Data Interpretation, Statistical
Foot / physiology*
Models, Biological*
Models, Statistical
Reference Values
Running / physiology*
Stress, Mechanical

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