As there is a lack of investigating the relationship between respiratory thresholds (ventilatory threshold (VT), anaerobic threshold (AT) and respiratory compensation point (RCP)) and fat oxidation, this study aimed to determine: 1) the reliability of the different respiratory thresholds as VT, AT and RCP, and 2) the percentage of fat oxidation at VT, AT and RCP in untrained young subjects. Fifty two sedentary subjects volunteered in a ramp test-retest protocol with 1 minute increments to detect VO2peak on a treadmill until complete exhaustion. The way of measurement and calculation method...