Does Ketone Ester Supplementation Boost Cycling Performance?

Marc van Impe

July 17, 2019

The Dutch pro-cycling team Jumbo-Visma is enjoying success in the Tour de France but how much of that is due to their use of ketones supplements?

Their rider Mike Teunissen took the yellow jersey for his victory on stage one. They won the team time trial and have had more stage wins with Dylan Groenewegen and Wout van Aert.

Team manager Richard Plugge told De Telegraaf newspaper this week: "Ketones are a dietary supplement. You can use them just like vitamins. The substance is not on the prohibited list, and it's also known that other teams use ketones."

After his victory, Wout van Aert, told TV reporters: "Ketones are not illegal. In essence, it is no more than a supplement. No more, no less. I see it this way: those ketones are similar to the gels that every rider eats. Only, the taste is bad."

The management of team Lotto-Soudal also admitted that some riders use ketones. "We use it, but not structurally", Dr Servaas Bingé told Flemish TV station VRT.

Ketones Evidence

In April, the  Journal of Physiology published an article entitled 'Ketone ester supplementation blunts overreaching symptoms during endurance training overload'. In plain language: ketones do help to improve performance.

The research in the article dates from last year and is the subject of Chiel Poffé's university PhD at KU Leuven. Co-author Peter Hespel, professor of physiology at Leuven, was the first in Belgium and one of the first in the world, to work with ketones outside the UK.

Ketones came on the radar of the US Army when the military investigative body Darpa (Defense Advanced Research Projects Agency) was looking for a compact, light, direct source of energy that would not spoil in hot environments, such as a desert.

Darpa put out a tender to synthesise ketones. That tender - worth $10 million - was won by Professor of Biochemistry Kieran Clarke of Oxford University, an Australian researcher who also worked at Harvard.

Kieran Clarke and Peter Hespel are pioneers in the field of ketone research. Professor Clarke admits that the top athletes of UK Sport had access to the product years earlier. "It has been used in the run-up to the London Games in 2012, but only by a select group of athletes because we had very few ketones. The Sky cycling team had it too, no doubt, but also via UK Sport," she's been quoted as saying.

Performance Enhancing

Kieran Clarke is seen as the 'inventor' of ketone therapy. She had managed to produce ketones outside the body and started testing. Not on the military because Darpa was eventually dropped, but on patients and athletes. The latter was by chance, because a researcher in her lab had a top-class sporting history as a rower and immediately saw the potential for endurance athletes.

For the Leuven study, 18 well-trained men were divided into two groups and received 3 weeks of endurance training. Nine were given ketones and nine others a placebo. In the third week the power output in the ketone group was no less than 15% higher in the last half hour of a 2-hour training session. There was more. In the placebo group the maximum heart rate dropped by 20 beats - a typical effect of fatigue through training is a delayed (sub) maximum heart rate - but in the ketone group it decreased by only 10 beats. The energy balance in the ketone group remained positive, but became heavily negative in the control group. In both groups the hormone GDF-15 rose, but twice as fast in the group without ketones.

At the beginning of July, ahead of the start of Le Tour in Brussels, Peter Hespel explained his experiences with ketones at the Science & Cycling conference: "There is every indication that GDF-15 may be the long-sought-for marker for the diagnosis of overreaching and training. One of the most spectacular spin-offs of the study was the observation that the ketone group was less prone to osteoporosis, something that sometimes takes on disastrous proportions among cyclists."

The first scientific article of importance for the sport appeared in the summer of 2016 in the trade journal Cell Metabolism. The title was: 'Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes'. In summary, ketones help. But how much do they help? Three percent, said the study. Three percent is the difference between gold and not making the podium.

Ketones Approval

In 2018, ketones were sold for the first time to non-insiders. Professor Clarke had sold a licence to the American company HVMN, an innovative firm run by young scientists. 

In the US, ketones have been approved by the Food and Drug Administration (FDA) as 'food', not even as 'nutraceutical' or food supplement. This is not yet the case in Europe, says Prof Clarke: "They are produced in Great Britain, then exported to the USA and from there they are distributed. Getting approval from EFSA (European Food Safety Authority) in Europe can take years."

Use of ketones is not considered to be doping by the World Anti-Doping Agency (WADA) but as part of a balanced diet alongside fats, carbohydrates, and proteins.

However, some reports say the voluntary membership group Mouvement Pour un Cyclisme Crédible (MPCC) may want restrictions on ketones in future.

Translated and adapted from MediQuality, Medcape's sister site for Belgium and the Netherlands.

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