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Determination of Maximal Lactate Steady State in Healthy Adults: Can NIRS Help?
MedLine Citation:
PMID:  23274611     Owner:  NLM     Status:  Publisher    
PURPOSE: We tested the hypothesis that the maximal lactate steady state (MLSS) can be accurately determined in healthy subjects based on measures of deoxygenated hemoglobin (deoxyHb), index of oxygen extraction measured non-invasively by near-infrared spectroscopy (NIRS). METHODS: 32 healthy men (average age 48±17 yrs, range 23-74 yrs) performed an incremental cycling test to exhaustion and square wave tests for MLSS determination. Cardiorespiratory variables were measured bbb and deoxyHb was monitored non-invasively on the right vastus lateralis with a quantitative NIRS device. The individual values of V˙O2 and heart rate (HR) corresponding to the MLSS were calculated and compared to the NIRS-derived MLSS (NIRSMLSS) that was, in turn, determined by double linear function fitting of deoxyHb during the incremental exercise. RESULTS: V˙O2 and HR at MLSS were 2.25±0.54 L·min (76±9 % V˙O2max) and 133±14 b·min (81±7 %HRmax) respectively. Muscle O2 extraction increased as a function of exercise intensity up to a deflection point, NIRSMLSS, at which V˙O2 and HR were 2.23±0.59 L·min (76±9 % V˙O2max) and 136±17 b·min (82±8 %HRmax) respectively. For both V˙O2 and HR, the difference of NIRSMLSS from MLSS values was not significant and the measures were highly correlated (r=0.81 and r=0.76). The Bland Altman analysis confirmed a not significant bias for V˙O2 and HR (-0.015 L·min and 3 b·min, respectively) and a small imprecision of 0.26 L·min and 8 b·min. CONCLUSIONS: A plateau in muscle O2 extraction was demonstrated in coincidence with MLSS during an incremental cycling exercise, confirming the hypothesis that this functional parameter can be accurately estimated with a quantitative NIRS device. The main advantages of NIRSMLSS over lactate-based techniques are the non-invasiveness and the time/cost efficiency.
Cecilia Bellotti; Elisa Calabria; Carlo Capelli; Silvia Pogliaghi
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-12-27
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  -     ISSN:  1530-0315     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-31     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Department of Neurological, Neuropsychological, Morphological and Exercise Sciences, School of Exercise and Sport Sciences, University of Verona, Italy.
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