Nutrition, Podcast

Race nutrition and hydration – current best practices with Andy Blow | EP#293

 July 5, 2021

By  Mikael Eriksson


Andy Blow, founder of Precision Hydration, returns to the podcast to discuss current best practices in race nutrition and hydration. Andy has a first-row seat to see what some of the best professional athletes in the world are doing, and shares the common patterns and potential differences, as well as how things might or might not differ for amateur athletes.

In this Episode you'll learn about:

  • Andy's and Precision Hydration's work with pro triathletes and other endurance athletes
  • What are the common patterns and trends across these top athletes, and what are the differences?
  • Getting down to the specifics: what formats of carbohydrate are they typically consuming
  • Logistics: what nutrition and hydration to carry with you, and how to carry it?
  • Should you be completely self-sufficient or also rely on aid stations
  • The case for going really high (90+ g/h) on carbohydrates in race nutrition, and training your gut to be able to do that
  • Hydrogels, and what the science currently says about how they work

Sponsored by:

Precision Fuel & Hydration
Precision Fuel & Hydration help athletes personalise their hydration and fueling strategies for training and racing. Use the free Fuel & Hydration Planner to get personalised plan for your carbohydrate, sodium and fluid intake in your next event. That Triathlon Show listeners get 15% off their first order of fuel and electrolyte products. Simply use this link and the discount will be auto-applied at the checkout.


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03:50 -

  • My name is Andy Blow and I am the founder and CEO of Precision Hydration.

    I was myself an avid triathlete even though I am retired now.

    Precision Hydration has been around for 10 years now and we are involved in a broad variety of sports, but our main focus is within endurance sport.

Working with professional athletes

05:50 -

  • Our way of sponsor and working with professional athletes differ slightly from other companies.

    Most commonly, a professional athlete is contacting us as they are having issues with nutrition or hydration during a race.

    We then help the athletes to figure out a highly individual hydration and nutrition plan for their races.

    To determine sodium concentration in the sweat, we do a proper sweat test.

    We mainly focus on the hydration and electrolyte in the athletes and not equally much on nutrition (carbohydrate intake).

Carbohydrate intake during racing

15:00 -

  • There aren’t too much inter individual differences between carbohydrate intake as there are for sweat rate and sweat sodium concentration.
  • There is a trend towards trying to take in more and more carbohydrate on an hourly basis, up to 100g or even 120g of carbohydrates per h.

    In a 70.3, most age grouper target an hourly intake between 60-90g/h, which appears to be working well.

    For an IM, most people would like to target the higher end of this spectrum, or even up towards 100g of carbohydrates per h, because the intensity is lower, the duration is longer and the energy intake is a bigger limiting factor.
  • In terms of type of carbohydrates, in a 70.3, most people would like to stick to gels and liquids whilst most athletes (even professionals) tend to want to take in some kind of solid food during an Ironman.
  • For marathon and Olympic distance triathlons, it is not equally common to take in nutrition, but the trend is still going in that direction, however, then probably only 50-60g/h is targeted, rather than the typical 90g that is often discussed for long and middle distance triathlons.

Training the gut

40:30 - 

  • Being able to increase your gut’s ability to tolerate and absorb plenty of energy seems to be very trainable, especially for unexperienced athletes.
  • In order to get to know where your intake limit is, testing different strategies and relating them to performance and/or any levels of gastro intestinal distress is the recommended way to go.
  • In your preparations for longer distance races (typically the Ironman distance), it is absolutely paramount to getting your body and gut accustomed to your race nutrition strategy.

    Ideally, your race nutrition plan should be practiced during sessions similar to your targeted race, this could for instance be a longer brick session at close to target race pace.

    It is rather unclear if practicing taking in your planned race nutrition on more or less every single training session will have an additional effect.
  • I use to recommend athletes to target two sessions per week, starting 6 weeks prior a race where they focus very highly on their nutritional intake.

    They start by for instance taking in 50g of carbohydrates/h and for each session they increase this number until they start developing GI distress, that is basically how much they can tolerate.

    There are few things within sport that are, the more the better, but when it comes to carbohydrate intake during an endurance race, that is basically it!

Carrying the nutrion on race day

49:10 - 

  • Most athletes tend to chose to empty gels into a water bottle as this makes things easier from a practical standpoint on race day.

    The downside is that it takes away the opportunity to have an extra bottle with liquids.

New gel technology

55:30 -

  • Recently developed energy drinks like Maurten does have a very high carbohydrate concentration but the gastric uptake is supposed to be enhanced by incapsulating the carbohydrates in a special way facilitating the gastric emptying process, however, it is still rather unclear if this technique leads to any performance gains.
  • Don’t get too carried away by intense marketing such as the hydrogel technology advertised by Maurten, the gains are probably marginal at best.

How to combine energy, fluid and electrolyte intake

01:01:15 -

  • I use to recommended separating your fluid and electrolyte intake from your energy intake as much as possible.

    There is evidence for that you can absorb fluid and electrolytes much more efficiently if the intake is not combined with plenty of carbohydrates.

    Newly developed sports drinks that are advertised to break down the carbohydrates more slowly, leading to a more stable energy release seem to fit certain athletes well, but in the end, for most people, the most important aspect is to get the fundamentals right, i.e. to get the right proportion of components in during a specific time frame.

How can you finish a 9h race if you sweat 2000ml/h but the body can only absorb 1000ml/h?

01:07:30 -

  • To start with, I wold like to say that there is a big margin of error in most calculations, for instance, if you measure your sweat rate during 1h at race intensity, it is not certain that the sweat rate will remain the same throughout the rest of the day.

    The same applies for absorption rate.
  • However, my best answer to the question is that the body is great at homeostasis (maintaining it’s inner balance), the body will correct any deficits by up regulating thirst, forcing you to reduce intensity, cut blood flow to the skin, which leads to less sweating etc.

    Moreover, you can also allow to finish the race being around 5 % dehydrated.

Rapid fire questions

01:16:20 -

  • What is your favorite book, blog or resource related to endurance sport? Gordo Byrn’s blog (he is a retired triathlete)
  • What is your favorite piece of gear or equipment? My gravel bike.
  • What is a personal habit that has helped you achieve success? I am an early riser, and I use to have gotten a lot of done before 9am.


Mikael Eriksson

I am a full-time triathlon coach, founder of Scientific Triathlon, and host of the top-rated podcast That Triathlon Show. I am from Finland but live in Lisbon, Portugal.

Please contact me if you have feedback on the podcast or want to make suggestions for improvement or send in a question for a Q&A episode.

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  • great episode. Hope novice athletes wont confuse experimenting with standard maltodextrin gels .. hoping any 90g will do the job.

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