| Several
methods are used for estimating the anaerobic threshold (AT) during
exercise. The aim of the present study was to compare AT values based
on blood lactate measurements with those obtained from computerised
calculations of different respiratory gas indices. Twelve healthy,
well-trained men performed a stepwise incremental test on both treadmill
and cycle ergometer. Respiratory gases were measured continuously,
and blood samples were drawn every third minute. AT was determined,
based on 1) blood lactate concentrations (Lactate-AT), 2) respiratory
exchange ratio (RER-AT), 3) V- slope method (Vslope-AT), and 4) ventilatory
equivalent for VO2 (EqO2-AT). Lactate-AT and RER-AT values showed
similar values, both on treadmill and on cycle ergometer. EqO2-AT
showed a trend towards lower values for AT, while Vslope-AT gave significantly
lower values for AT for both exercise modes. Bland-Altman plots showed
an even distribution of data for RER-AT, while a more scattered and
skewed distribution of data was observed when EqO2-AT and Vslope-AT
were compared with Lactate-AT. The study demonstrates that RER-based
estimates of AT correlate well with the blood lactate-based AT determination.
The RER method is non-invasive and simple to perform, and, in the
present study, seemed to be the best respiratory index for estimation
of AT.
KEY
WORDS: Anaerobic threshold, exercise test.
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