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 cross-sectional 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 single-day 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 ?= ?0.715) or heart rate ([163.2 ?± ?18.2] beat/min vs. [164.5 ?± ?16.1] beat/min, p ?= ?0.485). The MFO-V?O2max protocol test demonstrated excellent reliability (intraclass correlation coefficient ?= ?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. © 2025 Chengdu Sport University