Comparison of the Ramp and Step Incremental Exercise Test Protocols in Assessing the Maximal Fat Oxidation Rate in...

The incremental exercise test is the most common method in assessing the maximal fat oxidation (MFO) rate. The main aim of the study was to determine whether the progressive linear RAMP test can be used to assess the maximal fat oxidation rate along with the intensities that trigger its maximal (FAT_max) and its minimal (FAT_min) values. Our study comprised 57 young road cyclists who were tested in random order. Each of them was submitted to two incremental exercise tests on an electro-magnetically braked cycle-ergometer - STEP (50 W·3 min^-1) and RAMP (~0.278 W·s^-1) at a 7-day interval. A stoichiometric equation was used to calculate the fat oxidation rate, while the metabolic thresholds were defined by analyzing ventilation gases. The Student's T-test, Bland-Altman plots and Pearson's linear correlations were resorted to in the process of statistical analysis. No statistically significant MFO variances occurred between the tests (p = 0.12) and its rate amounted to 0.57 ± 0.15 g·min^-1 and 0.53 ± 0.17 g·min^-1 in the STEP and RAMP, respectively. No statistically significant variances in the absolute and relative (to maximal) values of oxygen uptake and heart rate were discerned at the FAT_max and FAT_min intensities. The RAMP test displayed very strong oxygen uptake correlations between the aerobic threshold and FAT_max (r = 0.93, R² = 0.87, p < 0.001) as well as the anaerobic threshold and FAT_min (r = 0.88, R² = 0.78, p < 0.001). Our results corroborate our hypothesis that the incremental RAMP test as well as the STEP test are reliable tools in assessing MFO, FAT_max and FAT_min intensities.