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The influence of mechanically and physiologically imposed stiff-knee gait patterns on the energy cost of walking.
MedLine Citation:
PMID:  22200391     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
OBJECTIVE: To investigate the relative roles of mechanically imposed and physiologically imposed stiff-knee gait (SKG) patterns on energy cost.
DESIGN: Repeated-measures, within-subjects design.
SETTING: Research laboratory.
PARTICIPANTS: Individuals (N=20) without musculoskeletal, neuromuscular, or cardiorespiratory limitations.
INTERVENTIONS: Participants walked on an instrumented treadmill at their self-selected overground gait speed for 3 randomly ordered conditions: (1) control, (2) mechanically imposed stiff-knee gait (SKG-M) using a lockable knee brace, and (3) physiologically imposed stiff-knee gait (SKG-P) using electrical stimulation to the quadriceps. Each condition was performed with 0% and 20% body weight support. Indirect calorimetry determined net metabolic power, and motion capture measured lower extremity joint kinematics and kinetics.
MAIN OUTCOME MEASURES: Net metabolic power, knee flexion angle, circumduction, hip hiking, and hip flexion and ankle plantarflexion moments.
RESULTS: Participants walked at 1.25±.09m/s. Net metabolic power was significantly increased by 17% in SKG-M and 37% in SKG-P compared with control (mean increase: .66±.60W/kg for SKG-M; 1.39±.79W/kg for SKG-P; both P<.001). Furthermore, SKG-P required greater net metabolic power than SKG-M (P<.001). Simulated SKG was associated with increased circumduction and hip hiking. Despite no change in ankle plantarflexion moments (P=.280), the hip flexion moment was increased during SKG-P (.43±.15Nm/kg·m) compared with control (.31±.08Nm/kg·m; P<.001).
CONCLUSIONS: The increase in energy cost associated with simulated SKG was due in part to abnormal mechanical compensations, and in part to an increase in quadriceps activity. Understanding the mechanisms underlying the increase in quadriceps activity will enable a reduction in the energy cost of walking with SKG.
Authors:
Michael D Lewek; Abigail J Osborn; Clinton J Wutzke
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Archives of physical medicine and rehabilitation     Volume:  93     ISSN:  1532-821X     ISO Abbreviation:  Arch Phys Med Rehabil     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2011-12-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985158R     Medline TA:  Arch Phys Med Rehabil     Country:  United States    
Other Details:
Languages:  eng     Pagination:  123-8     Citation Subset:  AIM; IM    
Copyright Information:
Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.
Affiliation:
Department of Allied Health Sciences, Division of Physical Therapy, University of North Carolina, Chapel Hill, NC; Human Movement Science Program, University of North Carolina, Chapel Hill, NC.
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