Validity and reliability of V˙O2max determination immediately after a maximal fat oxidation assessment in pre-diabetes/type 2 Diabetes Mellitus population

Abstract

Background: Measuring maximal fat oxidation (MFO) and maximal oxygen consumption (V_ O2max) typically requires two separate days, which can be time-consuming. This study aimed to assess the validity and reliability of a single-day test for measuring MFO and V_ O2max in individuals with pre-diabetes/type 2 diabetes (T2DM). Methods: Twenty adults with pre-diabetes/T2DM (10 women; [53.1 8.8] years) participated in this crosssectional study. Participants underwent a single-day MFO- V_ O2max protocol, followed by the traditional V_ O2max test on a cycle ergometer 4–7 days later, with both assessments performed using indirect calorimetry. The singleday test commenced with the MFO test, involving 15 W per 3 min increments until the respiratory exchange rate reached 1.0. After a 5-minute (min) rest, the V_ O2max test was conducted, starting at the last load and increasing by 15 W⋅min-1 until voluntary exhaustion. The traditional V_ O2max test involved a 15 W⋅min-1n incremental protocol until voluntary exhaustion, followed by a verification test at 110% of the previous maximum load. Results: No significant differences were observed between MFO-V_ O2max and traditional V_ O2max protocol in V_ O2max values ([2 099.4 534.1] ml⋅min-1 vs. [2 119.1 548.3] ml⋅min-1, p ¼ 0.715) or heart rate ([163.2 18.2] beat/ min vs. [164.5 16.1] beat/min, p ¼ 0.485). The MFO-V_ O2max protocol test demonstrated excellent reliability (intraclass correlation coefficient ¼ 0.957), limits of agreement ranging from 300.06 ml⋅min-1 to 306.77 ml⋅min-1, and the standard error of measurement was 181.67 ml⋅min-1. Conclusions: Therefore, the single-day test is a valid and reliable method for assessing both MFO and V_ O2max in men and women with pre-diabetes/T2DM. With a mean total duration of (34 8) min, this test enhances clinical applicability by significantly reducing the time and cost associated with traditional assessments.