There is increasing interest in the effect that ketones might have on the performance of athletes. We know that by consuming a diet very low in carbohydrates – less than 50 grams per day or so – we can enter ketosis or increase the circulating concentration of ketones in the blood. That’s why these diets are called ‘ketogenic’ (1, 8). In recent years, supplements have been developed that allow us to increase our circulating ketone concentrations independently of our habitual diet. These are the so-called ‘exogenous ketone supplements’ (9).

There are various types of exogenous ketone supplements, including ketone esters, ketone salts, and ketone precursors (that are converted into ketones in the body). Ketone salts combine ketones with sodium, potassium, calcium, or magnesium, and, predictably have the potential to provide a very high salt load. Ketone salts tend to provide a modest elevation in blood ketone, specifically D-βHB,...

Exogenous ketones have generated a lot of buzz in the endurance sports community over the last few years. Exogenous ketones are not to be confused with the ketones that circulate in the blood after adaptation to a very low carbohydrate, high fat, ketogenic diet; exogenous ketones are instead ingested in a supplement like a sports drink in much the same way that carbohydrates might be. There are a number of different types of exogenous ketones (6), with ketone monoesters seeing the most attention.

It was initially thought that, again like carbohydrates in sports drinks, taking on exogenous ketones during exercise might provide us with an alternative fuel source to help power long duration exercise and reduce use of our finite glycogen stores. There has been some indication that exogenous ketones do help us reduce glycogen use during exercise (2), although probably not via direct burning of the ketones to supply energy; the effect instead likely relates to some kind of signalling...

We all love a good "pain face" and we all know how much those high intensity interval sessions hurt! Such big sessions, require big recovery; and recovery optimization is always a key question for athletes, sports scientists and coaches looking for a performance advantage. With media reports circulating that many elite road cycling teams are investing huge sums of money in exogenous ketone supplements for their athletes (7), many of us in endurance sport – including the scientists – are asking if exogenous ketones are the next magic bullet in sports nutrition (4). We blogged about exogenous ketones recently, specifically using some of our own data and a recently published review (8) to survey the evidence for supplementing with exogenous ketones during a long-distance triathlon. In this blog, we are going to focus instead on the possible benefits of exogenous ketone supplementation for recovery.

Background

Before diving into specific original studies assessing...

- Dr Dan Plews and Ed Maunder

A review of the review by David M. Shaw et al. Sports Medicine 50(4): 641-656, 2020

In this blog, we are going to summarize a recently published review by former AUT PhD student Dave Shaw on the evidence for and against exogenous ketone ingestion (11), as well as some of our own personal experiences. Dave’s PhD included studies on both the ingestion of exogenous ketones in a sports drink and longer-term adaptation to a very low-carbohydrate, ketogenic diet (10, 12), with one of the main purposes of this review being to highlight the stark differences between these two interventions. In this blog however, we are going to focus on studies of exogenous ketone supplementation for endurance performance. Ed (PhD student & Endure IQ LDT102 guest instructor) was fortunate enough to be part of the team of authors writing the review.

Exogenous ketones 

A point here to note is that when we discuss exogenous ketones, we are not...