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Pulmonary Oxygen Uptake Kinetics during Exercise in Subclinical Hypothyroidism.
MedLine Citation:
PMID:  24512502     Owner:  NLM     Status:  Publisher    
Background: Patients with subclinical hypothyroidism (SCH) have lower exercise tolerance, but oxygen uptake (VO2) kinetics is unknown. This study evaluated VO2 kinetics during and after a constant load submaximal exercise in SCH. Methods: The study included 19 women with SCH (TSH = 6.87 ± 2.88 μIU / ml, T4 = 0.97 ± 0:15 ng / dl) and 19 controls (TSH = 2.29 ± 0.86 μIU / ml, T4 = 0.99 ± 0.11 ng / dl) aged between 20 and 55. Ergospirometry exercise testing was performed for 6 minutes with constant load of 50W, followed by six minutes of passive recovery. The VO2 kinetics was quantified by the mean response time (MRT), which is the exponential time constant and approximates the time needed to reach 63% of change in VO2 (∆VO2). The O2 deficit, energy supplied by anaerobic metabolism at onset of exercise, and O2 debit, extra energy demand during the recovery period, was calculated by the formula: MRT . ∆VO2. Values are mean ± standard deviation. Results: In the rest-exercise transition, patients with SCH showed slower VO2 kinetics (MRT = 47 ± 8 vs. 40 ± 6 s, P = 0.004) and higher oxygen deficit (580 ± 102 vs. 477 ± 95 ml, P = 0.003) than controls, respectively. In the exercise-recovery transition, patients with SCH also showed slower VO2 kinetics (MRT = 54 ± 6 vs. 44 ± 6 s, P = 0.001) and higher oxygen debit (679 ± 105 vs. 572 ± 104 ml, P = 0.003). The VO2 kinetics showed significant correlation with TSH (P < 0.05). Conclusions: This study demonstrates that women with SCH have slowest VO2 kinetics in the onset and recovery of a constant-load submaximal exercise and highlights that this impairment is already manifest in the early stage of the disease.
Francisco Zacaron Werneck; Emerson Filipino Coelho; Jorge Roberto Perrout de Lima; Mateus Camaroti Laterza; Marselha Marques Barral; Patrícia de Fátima Dos Santos Teixeira; Mário Vaisman
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-2-10
Journal Detail:
Title:  Thyroid : official journal of the American Thyroid Association     Volume:  -     ISSN:  1557-9077     ISO Abbreviation:  Thyroid     Publication Date:  2014 Feb 
Date Detail:
Created Date:  2014-2-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9104317     Medline TA:  Thyroid     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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