Randle Cycle in Practice: a student exercise to teach glucose- and fatty acid metabolism in fasted, fed and exercised states.

Here we describe an approach and overall concept on how to train undergraduate university students to understand basic regulation and integration of glucose and fatty acid metabolism in response to fasting, intake of carbohydrates and aerobic exercise. During lectures and both theoretical and practical sessions, the students read, analyse, and discuss the fundamentals of Randle cycle. They focus on how metabolism is regulated in adipose tissue, skeletal muscle, and liver at a molecular level under various metabolic conditions. Subsequently, students perform one of four different trials: ) overnight fast followed by ingestion of jelly sandwiches and lemonade ; ) overnight fast followed by ingestion of a chocolate bar and a soda; 3) overnight fast followed by ingestion of carrots and ) light fast and aerobic exercise for 2 hours, while monitoring glucose- and fatty acid levels. The data from these trials clearly show that glucose levels are kept constant around 5 mM while fatty acid levels raise to 300-700 mM, after an overnight fast. Upon carbohydrate intake, glucose levels increase whereas fatty acid levels are reduced. In response to aerobic exercise, the glucose level is kept constant at 5 mM, while fatty acids levels increase over time. Collectively, the data clearly recapitulates the essence of Randle cycle. The exercise shows the great pedagogical value of experiments within practical courses to help students gain knowledge of energy metabolism and regulation of biochemical pathways. In an active learning environment, students successfully tackled physiological assignments, enhancing constructive communication and collaboration among peers.