#65 - Interactions between exercise and insulin with Professor Erik Richter
Sep 23, 2023
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Professor Erik Richter, renowned authority in glucose metabolism during exercise, discusses how exercise increases glucose uptake and insulin sensitivity in muscle. They explore topics such as glycogen breakdown, effects of exercise on insulin levels in diabetes, and the role of AMPK in glucose uptake. The complexity of exercise and insulin interactions, benefits of continuous glucose monitoring, and the importance of physical activity in our sedentary lifestyle are also discussed.
Exercise increases insulin sensitivity in the muscle, improving glucose uptake and utilization.
High-intensity exercise can reduce appetite temporarily through various mechanisms such as lactate and hormone regulation.
Regular exercise leads to chronic adaptations in the muscle that enhance glucose uptake, lasting for weeks and benefiting overall health.
Deep dives
Exercise enhances insulin sensitivity and decreases appetite
Exercise, whether it is high intensity or endurance training, increases insulin sensitivity in the muscle. High-intensity exercise can reduce appetite for a period of time after the workout. The mechanisms behind this are not fully understood, but it is believed that factors like lactate, lack fee, and the hormone GDF 15 may influence appetite regulation. Fasting and energy deficiency can lead to insulin resistance, while regular exercise promotes insulin sensitivity in the muscle.
Molecular signaling and glucose uptake during exercise
During exercise, muscle contraction triggers molecular signaling pathways that translocate glucose transporters to the muscle membrane, promoting glucose uptake independent of insulin. This process involves various mechanisms, including AMPK activation, reactive oxygen species production, and the modulation of glute-4 protein and hexokinase expression. These mechanisms work together to increase glucose uptake during exercise. Additionally, increased blood flow during exercise enhances glucose delivery to the muscle, further enhancing glucose uptake.
Chronic effects of exercise on insulin sensitivity
Regular exercise, whether through resistance training or endurance exercise, leads to chronic adaptations in the muscle that increase insulin sensitivity. These adaptations include increased glute-4 protein expression, improved capillarization, and increased hexokinase activity. These changes contribute to enhanced glucose uptake and utilization in the muscle. The effects of exercise training on insulin sensitivity can last for weeks, providing long-term benefits for glucose metabolism and overall health.
Exercise enhances glucose uptake in muscles
Exercise increases the uptake of glucose in the muscle, independent of insulin. This effect lasts for several hours, making the muscle more insulin sensitive. This has clinical relevance, as it can improve insulin sensitivity in individuals with conditions such as diabetes or obesity.
Glucose transport in the gut and kidney
The mechanism by which glucose escapes metabolism in the gut and kidney is not fully understood. In the gut, glucose is transported through the epithelial cells without being metabolized, potentially via some unknown process involving the endoplasmic reticulum. In the kidney, glucose reabsorption occurs, but the exact transport mechanism is still not completely known. Future research is needed to explore these processes further.
Dr Glenn McConell chats with his great collaborator Professor Erik Richter from the University of Copenhagen in Denmark. Erik is an absolute authority and the godfather of the field of glucose metabolism during exercise and how exercise increases insulin sensitivity in muscle. He was the first to show that contraction can increase muscle glucose uptake without insulin but at the same time exercise increases insulin sensitivity. Very relevant for all including people with diabetes. We talked about how exercise increases glucose uptake during exercise and how it increases insulin sensitivity after exercise. Limitations of determining insulin sensitivity using the “gold standard” euglycemic hyperinsulinemic clamp vs meals. We also talked a little about how exercise can reduce appetite (GLP1 and lactate) . A very interesting, fun chat. Twitter: @proferikrichter.
0:00. Introduction and how Erik got into exercise research after medicine 3:05. Henrik Galbo, Jen Holst GLP1, glycogen, exercise 5:32. Adrenaline, glycogen breakdown and glucose uptake 7:20. Niel Ruderman: exercise and insulin sensitivity 9:32. Contraction increases glucose uptake independent of insulin 11:30. Relevance to type 1 diabetes 14:20. High intensity exercise increases blood glucose levels 16:15. Normal increases in insulin sensitivity after exercise in T2D 17:15. Regulation of glucose uptake into muscle during exercise 20:15. Appears AMPK not needed for glucose uptake during exercise 23:10. Reactive oxygen species and glucose uptake during exercise 24:05. Complexity of the many changes in muscle during exercise 27:00. Is there still a place for integrative physiology? 28:30. The incredible methods that Erik uses in human exercise studies 31:40. Limitations of using clamps for insulin sensitivity after exercise 35:35. Meals result in higher glucose uptake after ex than clamps 41:50. Is glucose uptake into non exercise muscle inhibited? 42:58. What need to consider when doing a clamp 45:10. Are continuous glucose monitors worth using? 47:32. Incretins (including GLP1) and insulin sensitivity after exercise 49:57. Effects of one bout vs chronic exercise (training) on insulin sensitivity 52:56. Does muscle glycogen stimulate insulin sensitivity? 57:51. Endurance vs resistance exercise for insulin sensitivity? 59:14. Erik’s impressive recent running times 59:54. HIIT, hyperglycemia, lactate, GDF15 and appetite 1:04:10. RED-S, fasting and insulin sensitivity 1:10:38. Gut glucose transport into the blood 1:15:16. A lot of glucose passes through the liver after exercise 1:16:20. How does glucose leave the capillaries to enter the muscle? 1:22:12. Takeaway messages 1:23:52. Outro (9 seconds)