The trial day breakfast will consist of energy estimated for each subject based on the Harris-Benedict equation with an activity factor of 30%. The diet will be 55:30:15 in terms of percent energy from carbohydrate:fat:protein. Subjects will consume the same diet on the days prior to each exercise trial to control for pre-study calorie and carbohydrate/fat intake, which could affect substrate oxidation. Subjects will refrain from consumption of alcohol and caffeine on the day of the trial. Trials will take place at least 5d (but no more than 10d) apart and will commence at a time between ~6-10am and will proceed according to the schematic timeline shown in figure 1. The testing time for subjects will remain consistent throughout the study. We also believe that it is prudent for subjects to consume a fixed and constant volume of water (500 ml with breakfast) during all trials to prevent dehydration and to allow subjects to complete the exercise in safe manner.