Ketones and Athletic Performance I: During Exercise

Currently, ketones are everywhere, appearing as if they were discovered with the same excitement as finding the Holy Grail in an Indiana Jones movie. Taking it further, a movie title might be, "Tadej Podagar: Raider of the Lost Ark of Ketones". Aside from the bad movie titles and jokes, what is the current obsession with ketones, and is it justified?

In the prior post (https://www.thethreshold.coach/single-post/understanding-fat-oxidation-and-athletic-performance-ii-practical-insights-and-recent-studies), we discussed fatigue resistance/durability and the importance of preserving muscle glycogen for enhancing performance, particularly concerning the W'Prime aspect following extended exercise where critical power was not as negatively impacted, but W'Prime/Functional Reserve capacity/anaerobic power was and further is important at the end of a race as a rider will go above the threshold repeatedly to win a race. This begs the question, can the ingestion of Ketones enhance performance by conserving muscle glycogen? Let's explore this further.

Questions we will attempt to answer:

1.What are Ketones?

-Types of ketone bodies

-Types of ketone supplements

2. Do ketones spare muscle glycogen during prolonged exercise and enhance exercise performance?

-What happens to performance when taking ketones during training and racing sessions

3. Summary

1.What are Ketones?

When carbohydrate intake is very low, the liver produces two forms of ketone molecules called d-beta-hydroxybutyrate (BHB) and acetoacetate (AcAc) from fatty acids. These ketones can serve as an alternative fuel source for muscles, with the idea being that this will conserve muscle glycogen during exercise. Acetoacetate (AcAc) is the primary ketone body derived from fatty acids, while acetone and BHB are produced from AcAc. Optimal ketone production is typically achieved when blood ketone levels reach around 0.5mmol, which can help induce ketosis naturally without the need for supplements. However, strict low-carb diets and intense physical activity should be monitored by professionals or at least guided to ensure safety.

Exogenous ketone products come in various forms that can be ingested orally, affecting absorption and boosting ketone levels in the bloodstream. These forms include ketone esters, ketone salts, and ketone precursors. Ketone salts tend to increase blood ketone levels modestly with a high salt load. In contrast, ketone esters tend to be bound to a ketone precursor, producing much larger increases in circulating blood ketones. The ester part of the bond comes in a monoester, diester, and triester configuration; most products on the market are in the monoester form (Shaw et al. 2020) shown below in Fig 2.

2. Do ketones spare muscle glycogen during prolonged exercise and enhance exercise performance?

Poffe et al 2020. attempted to answer this question.

Twelve cyclists were enlisted to cycle for 3 hours at an intensity corresponding to zone 2, typically between 60-90% of their first lactate threshold turn point (also called the aerobic threshold, generally below 2 mmol of lactate). It's important to note that FTP, for the sake of simplicity, usually coincides with the second lactate threshold (also known as the anaerobic threshold, "around" 4 mmol of lactate). They performed on two different days the following

Ketone Test:

60g of ketones (3-hyroxybutyl R-3-hydroxybutyrate) as 2x20 grams at 60mins before and then 20mins before 3 hour exercise session
20g at 30mins into the 3-hour exercise session

Control Test:

placebo that was the same amount, taste, and texture as ketones.

NOTE: they also used 60g/h of carbohydrates in ADDITION to the ketone/placebo

Results:

12 Cyclists	Ketones (60g) Test	Control (No ketones) Test
Rode 3 hours at Zone 2 (very aerobic) and then performed a 15-minute Time Trial	273w Average	272w Average
Level of Muscle Glycogen Depletion	56% (more depleted)	46% (less depleted)

3. Summary

The data indicates that ketones are not beneficial as a fuel WHILE exercising, and they might even lead to a greater depletion of muscle glycogen compared to not using ketones. In other words, NO PERFORMANCE enhancement DURING the exercise.
However, research has moved in the direction of using ketones AROUND exercise to enhance signals that come from training sessions.

In the upcoming blog post, we will explore the concept of utilizing ketones AROUND exercise sessions and discuss some of the positive effects found in recent research.

Any help with further questions, discussions, consultations, or coaching? Please don't hesitate to reach out to darrin@thethreshold.coach

@darrinjordaan

@wattfarming

Train Hard and Prosper!

Darrin Jordaan

MSc (Med) Biokinetics WITS

HMS (Hons) Sports Science UP

BK 0016934

CSCS

UCI Level 1 Cycle Certified Coach

IronMan Certified Coach

WADA Coaches of High-Performance Education Program Certified

References:

Poffe C, Ramaekers M, Bogaerts S, Hespel P. Exogenous Ketosis Impacts neither performance nor muscle glycogen breakdown in prolonger endurance exercise. Journal of Applied Physiology. Jun 1;128(6): 1643-1653. 2020.

Shaw DM, Merien F, Braakhuis A, Maunder E, Dulson DK. Exogenous ketone supplementation and keto-adaptation for endurance performance: Disentangling the effects of two distinct metabolic states. Sports Medicine (50): 641-656. 2020.