Fat oxidation can improve regardless of the actual fat burned during exercise, debunking the notion that exercising at low intensity (zone 2) is necessary for increasing fat oxidation.
Lactate levels do not significantly affect lipolysis (fat breakdown) during exercise, and the suppression of fatty acids is primarily due to reduced blood flow and albumin delivery to adipose tissue.
Cardiac drift, the upward drift in heart rate during prolonged moderate-intensity exercise, is a normal response to factors like increased skin blood flow and does not hinder performance or the benefits gained from exercise.
Deep dives
The Misconception of the Importance of Fat Oxidation during Exercise
There is a long-standing misconception that one needs to burn fat in order to improve fat oxidation. However, research shows that you don't have to burn fat to get better at burning fat. Endurance exercise training increases the capacity of muscles to oxidize fat as a fuel source, primarily through an increase in mitochondrial respiratory capacity. This increase can be achieved through various training methods, including high-intensity interval training and steady-state endurance training. The idea that you need to exercise at a low intensity, known as zone 2, to increase fat oxidation is not necessary. Fat oxidation can improve regardless of the actual fat burned during exercise.
The Inaccuracy of Lactate Inhibiting Lipolysis
There is a prevailing belief that lactate inhibits lipolysis or the breakdown of fats during exercise. However, this hypothesis is incorrect. Studies have shown that lactate levels do not significantly affect lipolysis, and in some cases, it may even increase the rate of appearance of glycerol, a marker of fat breakdown. The suppression of fatty acids during high-intensity exercise is primarily due to reduced blood flow and albumin delivery to adipose tissue, rather than lactate itself. The notion that it takes a prolonged period of time to reset metabolism after high-intensity exercise also lacks physiological basis.
The Myth of Cardiac Drift
Cardiac drift, or the upward drift in heart rate during prolonged moderate-intensity exercise, is a natural phenomenon that occurs in response to factors such as increased skin blood flow and reduction in central cardiovascular pressure. While it is true that heart rate may increase over time, it does not necessarily indicate a persistent change in metabolism or the need to slow down training. Various factors can influence cardiac drift, and it is a normal response that does not hinder performance or the benefits gained from exercise.
The Focus on Performance as the Ultimate Indicator
The focus of training should ultimately be on performance rather than specific physiological markers such as fat oxidation or lactate levels. Performance is the best predictor of performance, and training should be tailored to improve specific capabilities required for your chosen event. The idea of specific training zones or levels, such as zone 2, is not essential for achieving desired improvements in fitness and performance.
Focus on Adaptation and Progression
The podcast emphasizes that in training, it is important to focus on adaptation and progression to continue making improvements. When athletes reach a plateau in their training, they can either change their training approach or start competing to push their limits further. The key is not to become fixated on a specific training method, but rather to understand that there are different ways to achieve similar results. The example of different training approaches used by the top three finishers in the 5,000 meters race at the Tokyo Olympics highlights this point.
The Big Principles of Training
The podcast stresses the importance of understanding the big principles of training. While there is extensive research on the effects of exercise training, when it comes to prescribing a training program, there are only a few key principles to follow. These include specificity, overload, and reversibility. The podcast also cautions against getting caught up in the latest trends or obsessing over specific training zones. Instead, it encourages listeners to be skeptical consumers of information, consider the credibility of the source, and focus on the big picture of achieving their training goals.
Dr Glenn McConell chats for a second time with Associate Professor Andrew Coggan from Indiana University, Purdue University, Indianapolis (IUPUI), USA. Andy was an elite time trial cyclist who has a very impressive research track record. He also wrote the first book on training and racing using power (training levels). As was the case last week with Michael Joyner, Andy makes the case that different types of training can result in similar results (and there’s nothing special about zone 2). “Nothing magic about training at a particular intensity”. Andy was the first guest on Inside exercise in June 2022 talking about Nitrate and exercise.
0:00. Introduction and Andy’s cycling and research background 5:07. Andy’s cycling TTs and power based training 7:56. Andy’s early aerodynamic bike and aero positioning 10:56. His decision to develop cycling power levels 15:50. Wrote the first book on training and racing with power 17:00. Muscular metabolic fitness/lactate threshold 21:10. Onset of blood lactate accumulation (OBLA) 22:47. Little use having a one off lactate threshold test 23:55. Best predictor of performance is performance itself 24:25. Critical power / W’. Exercise intensity duration relationship 28:15. Zone based system around critical power 29:20. Training levels based on functional threshold power (FTP) 31:27. What is Zone 2? /long slow distance etc. 35:30. Lactate thresholds (LT1 and LT2)/continuum 37:55. Lactate threshold vs ventilation threshold 38:52. Don’t need to burn fat during ex to optimize fat use adaptations 41:07. Exercise intensity and fat use 43:45. What’s the best training program? 44:29. Same increases in ability to burn fat with HIIT 45:16. Lactate doesn’t inhibit fat use during exercise 51:40. Andy questions some interpretations of San Millan 53:10. Cardiovascular drift /aerobic decoupling 58:20. What to do if your performance plateaus 59:40. Exercise training programs: All roads lead to Rome 1:02:19. Specificity, overload, reversibility and different sports 1:04:34. Exercise training zones and intensity/duration 1:08:00. Physiological responses occur on a continuum 1:08:55. Quasi metabolic steady state 1:12:35. Wahoo 4 dimension power: “FTP is dead” 1:14:18. Takeaway messages/ the need for Inside exercise 1:17:32. Do people do zone 2 partly because it’s easy? 1:21:12. VO2 max does not change over a season 1:21:58. Demands of the event/characteristics of the athlete 1:23:57. Exercising and health (effects on the heart) 1:27:56. Outro (9 secs) Inside Exercise brings to you the who's who of research in 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). Connect with Inside Exercise and Glenn McConell at: Twitter: @Inside_exercise and @GlennMcConell1 Instagram: insideexercise Facebook: Glenn McConell LinkedIn: Glenn McConell https://www.linkedin.com/in/glenn-mcconell-83475460 ResearchGate: Glenn McConell Email: glenn.mcconell@gmail.com
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