Endurance athletic performance via anaerobic glycolysis issue?



Hello All,

I’ve been a recent ketoer and loving the lifestyle. I am looking into doing ensurance athletics, like ultramarathoning, etc… and in a lot of literature they indicate that ketogenic offers similar performance here is a quote… i wondered if there is any science to back this up?

from: http://trainright.com/should-endurance-athletes-go-keto-ketosis-ketogenic-diets-for-endurance-athletes/

Without stored and exogenous carbohydrate during competition, you have very little fuel available for anaerobic glycolysis, the metabolic shortcut that rapidly produces energy by partially burning carbohydrate to meet elevated energy demands during short, high-intensity efforts. Ketones can be converted to acetyl-coA and metabolized aerobically in mitochondria, but you miss out on the turbocharged boost from anaerobic glycolysis. You also miss out on the lactate produced from anaerobic glycolysis, but lactate isn’t the enemy it was once thought to be. It is partially-burned carbohydrate that gets broken down to usable energy.

The reason I say you’ll have little carbohydrate available for anaerobic glycolysis instead of no carbohydrate is because an athlete in ketosis can still produce glucose in the liver via gluconeogenesis. In plain English this means athletes in ketosis have limited capacity for high-intensity efforts that rely on carbohydrate for fuel. (It is intriguing to note the amount of available glycogen increased in the long-term fat-adapted athletes in Volek’s study with elite ultrarunners.)`

Luckily they do reference many papers, but I was curious what others thought. I am reading through those references and in the article they discuss that for intense prologned activity they recommend not doing keto since your liver can’t keep up.

References and Suggested Reading:

Burke, Louise M., Megan L. Ross, Laura A. Garvican-Lewis, Marijke Welvaert, Ida A. Heikura, Sara G. Forbes, Joanne G. Mirtschin, Louise E. Cato, Nicki Strobel, Avish P. Sharma, and John A. Hawley. “Low Carbohydrate, High Fat Diet Impairs Exercise Economy and Negates the Performance Benefit from Intensified Training in Elite Race Walkers.” The Journal of Physiology (2016).

Burke, L. M. “”Fat Adaptation” for Athletic Performance: The Nail in the Coffin?” Journal of Applied Physiology 100.1 (2006): 7-8.

Burke, Louise M. “Re-Examining High-Fat Diets for Sports Performance: Did We Call the ‘Nail in the Coffin’ Too Soon?” Sports Medicine 45.S1 (2015): 33-49.

Cox, Pete J., and Kieran Clarke. “Acute Nutritional Ketosis: Implications for Exercise Performance and Metabolism.” Extreme Physiology & Medicine. BioMed Central, 2014.

Cox, Peter J., Tom Kirk, Tom Ashmore, Kristof Willerton, Rhys Evans, Alan Smith, Andrew J. Murray, Brianna Stubbs, James West, Stewart W. Mclure, M. Todd King, Michael S. Dodd, Cameron Holloway, Stefan Neubauer, Scott Drawer, Richard L. Veech, Julian L. Griffin, and Kieran Clarke. “Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes.” Cell Metabolism 24.2 (2016): 256-68.

Havemann, L. “Fat Adaptation Followed by Carbohydrate Loading Compromises High-intensity Sprint Performance.” Journal of Applied Physiology 100.1 (2006): 194-202.

Marquet, Laurie-Anne, Jeanick Brisswalter, Julien Louis, Eve Tiollier, Louise M. Burke, John A. Hawley, and Christophe Hausswirth. “Enhanced Endurance Performance by Periodization of Carbohydrate Intake.” Medicine & Science in Sports & Exercise 48.4 (2016): 663-72.

Pinckaers, Philippe J. M., Tyler A. Churchward-Venne, David Bailey, and Luc J. C. Van Loon. “Ketone Bodies and Exercise Performance: The Next Magic Bullet or Merely Hype?” Sports Medicine (2016).

Volek, Jeff S., Daniel J. Freidenreich, Catherine Saenz, Laura J. Kunces, Brent C. Creighton, Jenna M. Bartley, Patrick M. Davitt, Colleen X. Munoz, Jeffrey M. Anderson, Carl M. Maresh, Elaine C. Lee, Mark D. Schuenke, Giselle Aerni, William J. Kraemer, and Stephen D. Phinney. “Metabolic Characteristics of Keto-adapted Ultra-endurance Runners.” Metabolism 65.3 (2016): 100-10.

Zajac, Adam, Stanislaw Poprzecki, Adam Maszczyk, Milosz Czuba, Malgorzata Michalczyk, and Grzegorz Zydek. “The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists.” Nutrients 6.7 (2014): 2493-508…

(Doug) #2

Hi Lucas. I just read something pertinent, here, which CarolT kindly gave a link to: http://www.sciencedirect.com/science/article/pii/S0026049515003340 A couple quotes:

“Compared to highly trained ultra-endurance athletes consuming an HC diet, long-term keto-adaptation results in extraordinarily high rates of fat oxidation, whereas muscle glycogen utilization and repletion patterns during and after a 3 hour run are similar.”

“Thus, we show for the first time that chronic keto-adaptation in elite ultra-endurance athletes is associated with a robust capacity to increase fat oxidation during exercise while maintaining normal skeletal muscle glycogen concentrations.”

The whole thing is a good read. The study subjects were elite athletes, but among them, I don’t think there was any problem with their livers not being able to keep up, among the low-carbohydrate group.

Here’s how the “Low-Carb” group was defined, for the study: “Subjects consuming an LC diet, defined as < 20% energy from carbohydrate and > 60% from fat, consistently for at least 6 months were eligible for the LC group.”

Less than 20% carbs is not as restrictive as it could be, but the performance of the group indicates they were very well fat-adapted, in my opinion.

(John) #3

This is correct, but also the opposite of what you are talking about. Anaerobic is very high intensity, all out effort like a sprint. Ketosis is not well suited for sprinters. However you mention endurance training and specifically ultra-marathon which is the opposite of that and is perfectly suited for Keto.

The FASTER study is the best I have personally read related to this so check it out here


@ianrobo has some personal experience with endurance riding including bouts of glycolytic sprints or climbs.

(ianrobo) #5

Remember you still have 2000 cals of glycogen energy, manage that in high intensity and very little need to top up.

It really all depends on your sport and targets. Currently in the Alps and report back next week what I found out.

(Amy pettis) #6

Following this discussion, as the reason I started keto was to avoid the ‘bonk’ during marathons. I’m training now for a marathon, and 50k, in October and have yet to bonk, but do feel like I’m running in mud some days.


You may also be interested in the discussion in these threads:

Basically, if you are using a higher percentage of fat throughout all zones, it actually preserves glycogen stores for when they are needed.

…and this one.

(Kevin von Duuglas-Ittu) #8

What did you find?

(Bunny) #9

I think the standard for this now is train-low\compete-high…

…ultra endurance athletes BURN 23x’s the SUGAR (glucose) and 2x’s the FAT, but that’s only AFTER 3 MONTHS of being in KETOSIS and not completely KETO ADAPTED (ketosis adaptation takes 6 MONTHS)…


•Metabolic characteristics of keto-adapted ultra-endurance runners - Jeff S. Volek - Nov 2, 2015

•The Effects of a Ketogenic Diet on Exercise Metabolism and Physical Performance in Off-Road Cyclists - Adam Zajac, Stanisław Poprzecki, and Grzegorz Zydek

•Ketogenic diets and physical performance - Stephen D Phinney

•Endurance athletes who ‘go against the grain’ become incredible fat-burners Elite performance on a diet with minimal carbs represents a paradigm shift in sports nutrition - November 17, 2015 Source: Ohio State University

(ianrobo) #10

well I did the Marmotte, 160km 5km of climbing and in 2016 as a carb burner did it in 11hours and 2017 - 9 hours and with no extra food at all on the ride bar a few jelly babies …