Comparison Of Fat Oxidation Rates At Substrate Intersection In Sedentary Individuals And Athletes

Purpose: The aim of this study was to evaluate metabolic responses of athletic and sedentary men at maximal fat oxidation and crossover points that were determined by performance tests.Materials and Methods: 10 sedentary (22.1 +/- 0.5 years) and 11 athletic (22.3 +/- 0.6 years) volunteers participated in this study. Participants' exercise tests were performed on a treadmill. Maximal fat oxidation rates and metabolic responses at cross over point (COP) were measured by indirect calorimeter (Cosmed Quark CPET).Results: Sedentary individuals were classified as overweight whereas athletic individuals were classified as normal according to their body mass indices and sedentary individuals' body fat percentage were significantly higher than athletic participants. Although athletic participants' peak oxygen uptakes were significantly higher, maximal fat oxidation rates were similar at both groups. At COP where oxidation of carbohydrates predominate fat oxidation, both group's oxygen consumption rates were found to be similar. On the other hand, the ratio of oxygen consumption to maximal oxygen uptake at COP was significantly lower in athletic group.Conclusion: Athletic individuals', whom had higher oxygen uptake capacities, maximal fat oxidation rates and fat oxidation rates at COP were not significantly higher than sedentary individuals. This finding indicates that maximal aerobic capacity might not be the only determinant of fat oxidation.