The validity of the Moxus Modular metabolic system during incremental exercise tests: impacts on detection of small changes in oxygen consumption.
Eur J Appl Physiol. 2014 Jan 30;
Authors: Beltrami FG, Froyd C, Mamen A, Noakes TD
PURPOSE: We investigated the accuracy of the Moxus Modular Metabolic System (MOXUS) against the Douglas Bag Method (DBM) during high-intensity exercise, and whether the two methods agreed when detecting small changes in [Formula: see text] between two consecutive workloads ([Formula: see text]).
METHODS: Twelve trained male runners performed two maximal incremental running tests while gas exchange was analyzed simultaneously by the two systems using a serial setup for four consecutive intervals of 30ÃÂ s on each test. Comparisons between methods were performed for [Formula: see text], [Formula: see text], fractions of expired O2 (FeO2) and CO2 (FeCO2) and [Formula: see text].
RESULTS: The MOXUS produced significant higher (meanÃÂ ÃÂ±ÃÂ SD, nÃÂ =ÃÂ 54) readings for [Formula: see text] (80ÃÂ ÃÂ±ÃÂ 200ÃÂ mLÃÂ min(-1), pÃÂ =ÃÂ 0.005) and [Formula: see text] (2.9ÃÂ ÃÂ±ÃÂ 4.2ÃÂ LÃÂ min(-1), pÃÂ <ÃÂ 0.0001), but not FeO2 (-0.01ÃÂ ÃÂ±ÃÂ 0.09). Log-transformed 95ÃÂ % limits of agreement for readings between methods were 94-110ÃÂ % for [Formula: see text], 97-108ÃÂ % for [Formula: see text] and 99-101ÃÂ % for FeO2. [Formula: see text] for two consecutive measurements was not different between systems (120ÃÂ ÃÂ±ÃÂ 110 vs. 90ÃÂ ÃÂ±ÃÂ 190ÃÂ mLÃÂ min(-1) for MOXUS and DBM, respectively, pÃÂ =ÃÂ 0.26), but agreement between methods was very low (rÃÂ =ÃÂ 0.25, pÃÂ =ÃÂ 0.12).
DISCUSSION: Altho! ugh it was tested during high-intensity exercise and short sampling intervals, the MOXUS performed within the acceptable range of accuracy reported for automated analyzers. Most of the differences between equipments were due to differences in [Formula: see text]. Detecting small changes in [Formula: see text] during an incremental test with small changes in workload, however, might be beyond the equipment's accuracy.
PMID: 24477571 [PubMed - as supplied by publisher]
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