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Neuromuscular fatigue after maximal exercise in patients with cystic fibrosis.
MedLine Citation:
PMID:  21078561     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
The aim of this study was to determine whether patients with cystic fibrosis (CF), despite their ventilatory limitation, would develop neuromuscular fatigue of quadriceps muscles following a maximal cycling exercise. Eleven adults with CF (age=26.8±6.9years; forced expiratory volume in 1s=54.1±12.8% predicted) and 11 age-matched healthy subjects performed a maximal incremental cycle test with respiratory gas exchange measurements. Maximal voluntary contraction (MVC) and electromyographic (EMG) activity of the vastus medialis muscle were recorded before and after exercise. Neural and contractile properties of the quadriceps were also investigated using femoral nerve electrical stimulation. Patients had lower exercise capacity, peak oxygen uptake and MVC than controls. MVC fell significantly postexercise in both groups (CF: -20±10%, controls: -19±6%; p<0.01). EMG root mean square values, M-wave amplitude and duration were unchanged in both groups. Peak twitch (-46.9±13.8%), maximal rate of twitch torque development (-50.3±13.8%) and relaxation (-35.2±19.5%) were all reduced after exercise in CF patients. The control group followed the same pattern (-38.4±14.4%, -42.1±14.7% and -15±20.4%) but the statistical significance was not reached for the maximal rate of twitch torque relaxation. In conclusion, CF patients demonstrated lower limb fatigue following symptom-limited cycle exercise, which was comparable to that exhibited by healthy controls. This fatigue may be due to contractile impairments and not to transmission failure. Further studies should be conducted in a larger sample to confirm these preliminary results.
Authors:
J M Vallier; M Gruet; L Mely; M Pensini; J Brisswalter
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology     Volume:  21     ISSN:  1873-5711     ISO Abbreviation:  J Electromyogr Kinesiol     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-02-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9109125     Medline TA:  J Electromyogr Kinesiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  242-8     Citation Subset:  IM    
Copyright Information:
Copyright © 2010 Elsevier Ltd. All rights reserved.
Affiliation:
Handibio, EA 4322, University of Toulon-Var, France.
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