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 30Â 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 (meanÂ Â±Â SD, nÂ =Â 54) readings for [Formula: see text] (80Â Â±Â 200Â mLÂ min(-1), pÂ =Â 0.005) and [Formula: see text] (2.9Â Â±Â 4.2Â LÂ min(-1), pÂ <Â 0.0001), but not FeO2 (-0.01Â Â±Â 0.09). Log-transformed 95Â % limits of agreement for readings between methods were 94-110Â % for [Formula: see text], 97-108Â % for [Formula: see text] and 99-101Â % for FeO2. [Formula: see text] for two consecutive measurements was not different between systems (120Â Â±Â 110 vs. 90Â Â±Â 190Â mLÂ min(-1) for MOXUS and DBM, respectively, pÂ =Â 0.26), but agreement between methods was very low (rÂ =Â 0.25, pÂ =Â 0.12).
DISCUSSION: Although 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]