(Boris Streubel/Bongarts/Getty Images)
Recently, Nike announced its plan to break the 2-hour marathon barrier in 2017. It is an audacious plan (some might say impossible), as it requires to reduce the actual record (2:02:57) by 2.5 %! But Nike is not the only player to work towards this crazy goal : Adidas also announced that they have been working on a similar project for 2 years. In addition, sub2hrs, a consortium of scientists and sports companies, has already claimed responsibility for some top-level performance, such as lthe near-2hr performance by K. Bekele during the last Berlin marathon (2:03:03).
Beyond the runners and their sponsors, breaking the 2-hour barrier is also a tremendous challenge for the exercise physiologists! Many areas of exercise science (biomechanics, metabolism, …) are impacted by this sub-2hour quest and sports nutrition will be a significant part of the equation.
In the next weeks, we will write a series of articles discussing how nutrition can help break the 2-hour marathon barrier. Today, let’s talk about the new secret drink that Bekele may have used in its last Berlin marathon.
EPISODE 1 : A new revolutionary drink?
During an endurance race, the ingestion of carbohydrates usually improves performance (check this article for the current guidelines). But are the more carbohydrates the better? Protocols with increasing carbohydrate intake have shown that their absorption and subsequent use as fuels are limited. Why is this?
First, our stomach tends to slowly release nutrient-containing drinks into our intestine instead of letting them flow through. Second, and there is still debate about this, it is possible that some carbohydrate transporters in our intestine (those who shuttle the sugars from the intestine to the blood) reach a maximal speed and could not keep up with very high carbohydrate concentrations.
1. Maurten and the hydrogels
A Swedish company, Maurten, claims it has found a way around some of these limitations : hydrogels! According to them, a hydrogel-based drink is emptied faster from the stomach than a normal sports drink. Is that really true? And is such a drink involved in Bekele’s stunning performance?
(a snapshot of the Maurten website)
First, what is a hydrogel? A hydrogel is a three-dimensional molecular network that can contain a lot of water. In this water-based gelly-like structure, it is possible to pack water-soluble molecules. These hydrogels have been used for example to package drugs and increase their lifetime in blood or increase their delivery. Now, imagine that, instead of therapeutic drugs, Maurten has packaged a lot of carbohydrates into a hydrogel, and that the hydrogel still is fluid enough so that you can drink it. Would this make it go faster through the stomach?
Well, the control of gastric emptying is a complex process, with many neuronal and hormonal influences. So, I won’t try try a theoretical answer but will focus on what has been tested. Old (but great!) studies have shown that the time of gastric emptying is highly dependent on the carbohydrate concentrations : the more carbs, the more the drink stays in the stomach! But they also have shown that osmolarity also plays a role. For the same carbohydrate concentration, low osmolarity drinks prepared with big polymers went faster through the stomach.
Wait, what is osmolarity? It is basically the number of molecules in a drink. We don’t think about it so much, but it is possible to achieve the same concentration, say 60 grams of carbohydrates / liter, with different types of carbohydrates. Indeed, If you use small single molecules, like glucose, you would need a lot of them to reach 60 grams, so the osmolarity will be HIGH. If you use, big, sweet polymers, like amylose or maltodextrins, you would need less molecules to reach 60 grams and the osmolarity will be LOW.
2. My bet on what a hydrogel drink can be
Back to Maurten, we can imagine that the hydrogels are entirely made of carbohydrates. Long polymers like amylose or pectin can easily form gels (the latter are used in fruit jams for example!). Interestingly, this hypothesis has been tested in 2000, by a group of UK researchers. And indeed, gastric emptying was faster in the gel-like drink!
So, although there is very very very limited information around the Maurten drink, here is my bet:
Maurten has formulated a hydrogel based on long carbohydrate polymers such as amylopectin. This gel/drink may go faster through the stomach, thus allowing to pack a lot of carbs in the drink and reduce tolerance issues.
UPDATE: Maurten revealed the main ingredients of the hydrogel drinks in an e-mail to its followers on March 6th 2017.
So : Maltodextrin, Fructose, Pectin, Sodium alginate and Sodium chloride. I wasn’t very far 🙂
The stuff that I haven’t seen coming is the fact that the drink is liquid at first but becomes a gel in the stomach, so at low pH. Clever… but I can’t really conceptualize how gastric emptying could be faster with a gel in the stomach…
3. Field testing
In an interview available on the sub2rs website, Andrew Bosch, associate professor and exercise science at the University of Cape Town, and involved in the nutritional aspects of the sub2hrs project, revealed interesting practical details about the hydrogel drink.
Bosch acknowledges field testing of the drink, thus implying it is at an advanced production stage. “It’s a powder that’s mixed with water”, says Bosch, suggesting that it doesn’t require a specific processing that would make the use of the drink impractical.
It seems that the purpose of the field experiment was to test the upper limit of concentration that is tolerable by the runners. The scientists tested increasing concentrations of carbohydrate-containing hydrogels and Bosch confidently reports: “they didn’t get an upset stomach or feel uncomfortably full”.
Interestingly, this testing happened in Ethiopia, in a running group that involved Bekele as “the main athlete”. This clearly supports the idea that the hydrogel drinks already are used during major running events, including by Bekele himself during the last Berlin marathon.
4. Remaining questions
All of these theoretical and practical news sound great, but there are still lots of questions to be answered.
1/ Are these extra carbohydrates indeed absorbed? Increasing gastric emptying doesn’t mean that the carbohydrates will be absorbed by the intestine.
2/ Are these extra carbohydrates really used to fuel the exercising muscle?
and, most important:
3/ Does it lead to an increase in endurance performance?
Maybe Maurten has all the answers and keeps them secret. Maybe they don’t and they need to do their homework.
Anyway, I bet that independent research groups will challenge this hypothesis and I’m excited to see the results. I’m also very excited to try to make hydrogels in my kitchen : be sure that I will share my own hydrogel recipe very soon!! We can’t be sure that this new hydrogel drink will allow an elite runner to break the 2-hr barrier but we can be sure it will shake the sports drink market!
CONCLUSION OF EPISODE 1
It is great to see how this crazy sub-2hr project fosters innovation in the field of sports nutrition! There is still a lot to explore in the field of exercise science and medicine and it is incredibly refreshing to re-discover that performance enhancement can be achieved without illegal doping. Yet, we may need to wait a long time before hydrogel drinks can be backed up by independent research! I’ll keep you posted!