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Original articles  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2003 December;43(4):437-43

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Reproducibility of the instant of equality of pulmonary gas exchange and its physiological significance

Laplaud D. 1, 2, Menier R. 1

1 Regional Center of Sports Medicine, Limousin, CHRU Dupuytren, Limoges, France, 2 UPRES EA3285, Physiologic Determinants of Physical Activity, Faculty of Sports Sciences, University of the Mediterranean, Marseille, France


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Aim. The ­goal of ­this ­work was to high­light the effec­tive­ness of a new sub­max­imal exer­cise ­index of ­aerobic endu­rance ­using a ­single incre­mental ­test: the ­time at ­which ­oxygen ­uptake and ­carbon ­dioxide ­output are ­equal, i.e., ­when the res­pir­a­tory ­exchange ­ratio (RER)=1.00. We ­studied 2 experi­mental ­sets, the 1st to ­assess the repro­du­cibility and the var­i­ability of meas­ured var­i­ables, the 2nd to ­assess the phys­io­log­ical sig­nif­i­cance of the ­instant RER=1.00.
­Methods. The 1st ­group con­sisted of 8 sub­jects who per­formed 3 max­imal ­ramp ­tests, the 2nd of 32 ath­letes. All sub­jects per­formed an incre­mental ­ramp ­test ­until exhaus­tion ­with deter­mi­na­tion of 1st and 2nd ven­til­a­tory and ­lactic thresh­olds (VT1-LT1, VT2-LT2) and the RER=1.00 ­instant.
­Results. ­There was no sig­nif­i­cant dif­fer­ence in the ­used frac­tions of ­reserves (UF r) for ­heart ­rate, ­oxygen ­uptake and ­power ­output for RER=1.00 ­between ­tests, the coef­fi­cients of vari­a­tion ­being non-sig­nif­i­cant. In ­group 2, ­there ­were no sig­nif­i­cant dif­fer­ence of UF r ­between VT1 and LT1, VT2 and RER=1.00, LT2 and RER=1.00. In con­trast, VT2 dif­fered sig­nif­i­cantly ­from LT2.
Con­clu­sion. Meas­ure­ment of the ­instant of ­equality of pul­mo­nary gas ­exchange was there­fore repro­du­cible ­with a low intra­in­di­vidual var­i­ability. More­over, it ­exists a con­cor­dance of the appa­ri­tions of VT1 and LT1 and ­between ­these of RER=1.00 and VT2 and LT2. ­Thus, ­with the ­instant RER=1.00 pro­vides the phys­iol­o­gist and the ­sports phy­si­cian ­with an effi­cient sub­max­imal ­tool to eval­uate ­aerobic endu­rance of ath­letes ­using a ­single incre­mental exer­cise ­test.

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