Consistency of Peak Fat Oxidation Rates During Treadmill Ergometry: A Pilot Protocol and Methodological Elaboration

Introduction: Maximizing fat oxidation is currently a major target in endurance sports. The aim of the present study was therefore, to (1) determine if a cycle ergometry protocol adapted to a treadmill investigational setting, would elicit potential peak fat oxidation rates; (2) Verify if these recorded variables were also maintainable throughout an endurance exercise bout. Methods: Six healthy and recreationally active adult runners (27±2.8y; 1.72±0.10m; 70±17kg, 23±2 (kg/m2), were examined. Subjects performed 3 different running protocols on a treadmill ergometer. For every test, breath-by-breath analysis was used to monitor metabolic activity and determine fat oxidation rates. Results: Peak fat oxidation rates occurred at different stages of the test for the majority of subjects (i.e. stage 1 for subject 4 (0.55g/min), stage 6 for subjects 6 (0.34g/min), stage 2 for subjects 1 and 5 (0.55 & 1.31g/min, respectively) and stage 5 for subjects 2 and 3 (0.60 & 0.56g/ min respectively). At the endurance test, subjects 2 (0.56±0.07g/min), 3 (0.48±0.13 g/min), and 6 (0.38±0.05g/min) achieved superior mean peak fat oxidation rates when compared to the previous test. The opposite was observed for subjects 1 (0.20±0.05g/min), 4 (0.26±0.05g/ min) and 5 (1.05±0.15g/min). Conclusion: At this stage, clear methodological impairments still need to be improved before estimations of peak fat oxidation can be used as a reliable training prescription tool.