The objective of this study was aimed to determine gender-based differences in fuel metabolism in response to long duration exercise. Another way of saying is through a simple question . . . Which gender metabolizes a greater amount of fats vs. carbohydrates at the same relative intensity level? Fuel metabolism responses from exercise were compared in a sample of 14 men and 13 women during a 2 hour (40% of maximal of uptake) of cycling and a 2 hour post-exercise recovery period. One of the women was released form the experiment because of the onset of menstruation, which the increased flux of hormones would deviate her results. The 27 subjects in the sample also completed a separate control day in which no exercise was performed and testing was performed. It should be noted that the (seven) trained subjects from each gender were competitive cyclist, and that all of the untrained subjects performed aerobic exercise less then 90 hours a weeks. All subjects were of normal weight, were nondiabetic and nonsmokers, and were not suffering from any medical conditions or taking any sort of medication. All of the subjects had their body composition taken, VO2 max and resting VO2 determined, and a health and physical examination performed in advance of the experiment at the University of Colorado’s Health Sciences Center. The purpose of this was so the subjects could all perform at the same relative intensity level and thus the results could be compared cross-sectionally. In the prior three days before the experiment, as well as during it, all subjects were fed a controlled diet consisting of 30% fat, 15% protein, and 55% carbohydrates. The purpose behind all of this was so that the independent variable would be the 40% relative intensity level performed by all subjects and the dependent variable was the change in each of the subject’s metabolism. Fuel oxidation was measured using indirect calorimetry using the metaboli...
