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Health & Exercise Physiology
Ketosis is a metabolic state in which the body breaks down fatty acids for energy source, thereby producing ketone bodies as a byproduct. It is often used by humans trying to decrease body fat, and/or increase exercise performance, as ketosis uses fat for fuel rather than glucose. Short-term caloric and carbohydrate restriction (fasting) promote ketosis; however, these nutritional limitations may impair exercise performance and health, if done excessively. The purpose of this project was to determine whether short-term fasting affects aerobic exercise performance in male and female mice. To test this, male and female mice were separated into fed and fasted groups and then subjected to a 100-minute endurance exercise test of fixed increasing speed intervals on a motorized treadmill. Fed mice were fed immediately prior to the exercise test. Fasted mice were fasted for six hours prior to exercise. Exhaustion was determined using a novel “Rest Test.” Following the exercise test, blood and skeletal muscle were collected from each mouse. Blood glucose and ketone bodies were measured using hand-held commercially available devices (Contour, Bayer Healthcare; Ketone Monitoring System, Keto-Mojo). Serum fatty acids levels were measured with a commercially available kit (Wako Diagnostics). Triglyceride and glycogen content from skeletal muscle were measured using established laboratory protocols. Preliminary findings suggest that endurance exercise capacity is improved in females with fasting, and reduced in males with fasting. This study is important since it investigates the relationship of nutrition, metabolism, and exercise performance. Findings from this study are critical in determining the safety of ketosis considering the popularity of the ketogenic diet for weight loss and usage of ketone supplements to improve exercise performance.
Holcomb, Lola, "The Effects of Short-Term Fasting on Endurance Exercise Capacity in Mice" (2019). Health and Exercise Physiology Summer Fellows. 13.