Exploring the Indirect Pathway in Liver Carbohydrate Metabolism

Dr Glenn McConell chats with Professor Javier Gonzalez from the University of Bath. We discuss carbohydrate (CHO) metabolism at rest when fasted vs fed, during exercise when fasted vs fed and the effects of exercise on metabolism after a meal. We also discuss muscle and liver glycogen resynthesis and the effects of different types and amounts of carbohydrate. Finally, we touch on Javier’s study with ketone supplementation and EPO.

0:00. Introduction
2:23. How got into exercise research
4:43. Metabolism at rest when fasted and in response to a meal
7:30. Effect of exercise on metabolism after a meal
9:15. Transient hypoglycemia during exercise after a meal (in some)
10:04. Effect of increasing amounts of glucose on blood glucose levels
12:21. Tracer studies to determine glucose turnover/flux
The glucose concentration does not tell us the rate of glucose appearance and disappearance. Need tracer methodologies to determine this.
18:06. Maximum rate of CHO can ingest during exercise
Glucose vs fructose etc.
20:55. Glycogen resynthesis after exercise
23:00. Indirect pathway of glucose metabolism in the liver
24:49. If exercising once per day generally don’t need to maximize glycogen levels
29:23. Glucose, fructose vs normal food/meals
31:17. Generally don’t need CHO loading or CHO ingestion if exercise is ~1hr
33:24. CHO backloading
35:52. Glucose spikes after eating are generally normal physiology
After a meal it is normal to have a “spike” (excursion) in glucose concentrations.
38:45. Research studies using fasted vs fed individuals
40:38. Time to exhaustion vs time trials
43:34. CHO ingestion reduces liver glycogen use
Is there a sensor from the liver to the brain that effects exercise performance?
46:28. Fasting, exercise intensity and CHO needs
49:03. Ingesting CHO and lactate measurements
50:50. Continuous glucose monitors
53:40. Often doesn’t find what he expected to in research
55:08. What’s he excited about right now?
58:35. Liver glycogenolysis vs gluconeogenesis during exercise
59:59. High exercise intensity and CHO metabolism
1:01:47. Different ways of measuring insulin sensitivity
The so-called gold standard to determine insulin sensitivity is the euglycemic hyperinsulinemic clamp but it’s so different to eating meals.
1:04:58. Ketones, exercise and EPO
1:07:32. Endurance athletes generally benefit from high CHO diets
1:09:04. Take home messages
1:12:08. Outro (9 seconds)

Inside Exercise brings to you the who's who of exercise metabolism, exercise physiology and exercise’s effects on health. With scientific rigor, these researchers discuss popular exercise topics while providing practical strategies for all.  

The interviewer, Emeritus Professor Glenn McConell, has an international research profile following 30 years of Exercise Metabolism research experience while at The University of Melbourne, Ball State University, Monash University, the University of Copenhagen and Victoria University.  

He has published over 120 peer reviewed journal articles and recently edited an Exercise Metabolism eBook written by world experts on 17 different topics (https://link.springer.com/book/10.1007/978-3-030-94305-9).  

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