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Sinusoidal High-Intensity Exercise Does Not Elicit Ventilatory Limitation in COPD.
MedLine Citation:
PMID:  23335005     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Rationale: During exercise at critical power (CP) in COPD patients, ventilation approaches its maximum. Because of the slow ventilatory dynamics in COPD, ventilatory limitation during supramaximal exercise might be escaped using a rapid sinusoidal forcing. Methods: Nine COPD patients (age=60.2±6.9yrs, FEV1=42±17% predicted, FEV1/FVC=39±12%) underwent incremental and then four constant work rate (CWR) cycle ergometer tests; tolerable duration (Tlim) was recorded. CP was determined from CWR testing by linear regression of WR vs. 1/Tlim. Patients then completed fast (FS, 60 s period) and slow (SS, 360 s period) sinusoidally fluctuating exercise tests with mean WR at CP and peak at 120% of peak incremental test WR, and one additional test at CP; each for a 20 minute target. Results: Tlim did not differ between CP (19.8±0.6 min) and FS (19.0±2.5 min), but was shorter in SS (13.2±4.2 min, P< 0.05). The sinusoidal ventilatory amplitude was minimal (37.4±34.9 ml.min-1.W-1) during FS, but was much larger during SS (189.6±120.4 ml.min-1.W-1). The total ventilatory response in SS reached 110±8.0% of the incremental test peak - suggesting ventilatory limitation. Slow components in ventilation during CWR and FS exercises were detected in most subjects and contributed appreciably to the total response asymptote. SS was associated with higher mid-exercise lactate concentrations (5.2±1.7, 7.6±1.7 and 4.5±1.3 mmol/l in FS, SS and CP). Conclusions: Large amplitude rapid sinusoidal WR fluctuation yields little fluctuation in ventilation despite reaching 120% of the incremental test peak WR. This high-intensity exercise strategy might be suitable for programs of rehabilitative exercise training in COPD.
Authors:
Janos Porszasz; Mehdi Rambod; Hester van der Vaart; Harry B Rossiter; Shuyi Ma; Rafi Kiledjian; Richard Casaburi
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-18
Journal Detail:
Title:  Experimental physiology     Volume:  -     ISSN:  1469-445X     ISO Abbreviation:  Exp. Physiol.     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-21     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1 Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center;
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