One particularly well-designed study has examined this very aspect. This study investigated whether highly-trained individuals are more capable of utilizing fat as a fuel source than untrained people, particularly after a bout of high-intensity cardio exercise.
In this study, researchers at Shriner’s Burns Institute in Texas asked six aerobically fit men and six untrained men to perform 30-minutes of exercise at 75-80% of their maximal oxygen consumption capacity (VO2max). The rates of appearance and disappearance of free fatty acids in the blood were measured (isotopic tracers of glycerol and palmitate), and the overall rate of fatty acid oxidation was determined using indirect calorimetry.
During these assessments, the whole-body rate of lipolysis (fat mobilization) and free fatty acid utilization was higher in the men with higher levels of fitness. From the results of this study, the scientists concluded that an individual’s fitness level influences their fat burning capacity. Aerobically-fit people do appear to burn more fat during the same exercise bout than people that don’t perform regular cardio exercise.
This information should motivate bodybuilders to stick with cardio exercise all year ‘round, not just before a contest. The higher level of cardio fitness you have directly results in a more efficient fat burning metabolism.
