Stability over time of the level of maximal lipid oxidation during exercise

Summary Introduction The level of maximal lipid oxidation at exercise (LIPOXmax or FATmax) is exercise intensity, variable among individuals, at which a steady-state exercise performed over 45–60 minutes uses the greatest lipid/carbohydrate ratio and thus, minimises carbohydrate waste. This level has been demonstrated to be highly reproducible if tested in standardised conditions and is modified by a host of physiological or pathological situations. Whether it is stable over long periods of time remained unknown. Methods We had the possibility to measure this stability in a database of 1600 exercise calorimetries performed in our unit since 1998 and including several patients that did not modify their exercise or eating habits and were re-tested after a mean interval of 30 months. Patients (n = 11) represented a wide range of age (28–74 years), body mass index (22 to 46.7 kg/m2) and aerobic capacity. Results Their LIPOXmax ranged between a power of 18 to 123 watts and their maximal fat oxidation rate (MFO) ranged between 75 and 423 mg/min. There was a remarkable stability of the LIPOXmax expressed in crude power (r = 0.993, P Conclusion Therefore, the power at which lipid oxidation reaches a maximal during exercise remains stable over a mean period of 30 months if diet and exercise habits are not modified.