Date of Award
Master of Science (MS)
School of Kinesiology and Recreation
Dale D. Brown
In order to produce mechanical energy through muscular activity, the body must oxidize chemical energy, carbohydrate, fat, or protein through metabolic processes, which then results in the production of ATP as mechanical energy through exercise. Total body metabolism, specifically skeletal muscle depends on factors such as the intensity and duration of exercise, substrate availability, and Training status. During exercise at low intensities (25% of VO2 max) fat is the primary macronutrient that is oxidized for energy. As the exercise intensity progresses, (65% of VO2 max) there is an alteration in skeletal muscle utilization, which results in mainly the use of carbohydrate energy. Intramuscular stores of carbohydrate and fat via muscle glycogen and muscle triglyceride are favorable at high intensity exercise, muscle glycogen more so than intramuscular triglyceride (85% of VO2 max). Although many studies have found this to be true in aerobic athletes, there is limited research on how high intensity exercise effects fuel metabolism in anaerobic trained individuals. PURPOSE: The purpose of this study was to examine how long term dietary intake effects fuel metabolism during increasing intensity aerobic exercise in resistance trained individuals. METHODS: 8 resistance trained individuals volunteered to participate in this study. Subjects completed a 5 day food log (3 weekdays, 2 weekend days that represented a consistent diet they had been following for > 4 weeks, once completed their macronutrient intake was averaged over the 5 days. Based off their percent intake subjects were placed into either a high carbohydrate (CHO) (>47%) group or low CHO (<47%) group. Subjects then completed one continuous Astrand Rhyming aerobic capacity treadmill test. Data was recorded through Indirect calorimetry measuring VO2, VCO2, and calculating respiratory exchange ratio (RER/RQ). Heart rate, RPE, and VO2max were also recorded. All data recorded by the VMAX system was compiled for each subject. Exclusion included anyone that did not met inclusion criteria or did not reach VO2max during the aerobic capacity test. Data was summarized for VO2max, %VO2max, RQ, %kcals of CHO and fat. The data was then compared between groups to identify if there was a difference in carbohydrate and fat oxidation between groups based off their dietary intake. RESULTS: The high CHO group had the greatest overall RQ at 100% VO2max, and there was no significant difference in RQ between groups at each percent of max. The low CHO group had a greater percent kcal of CHO, while the high CHO group had a great percent kcals of fat during the aerobic capacity test. There was no significant difference between %kcal of fat and CHO between groups. CONCLUSION: Overall, moderate changes in dietary intake do not significantly effect carbohydrate and fat utilization in resistance trained individuals during an aerobic capacity exercise.
Stephenson, Taylor Lynn, "The Effects of Dietary Intake on Fuel Metabolism during Aerobic Capacity Exercise" (2017). Theses and Dissertations. 777.