How this pro triathlete is using sweat rate data to improve his performance

By Abby Coleman | 4 Minute Read

We've spoken to three-time Norseman Xtreme Triathlon winner, Allan Hovda, about how he refined his hydration strategy after suffering some tough results in hot conditions in the past and he's taken those refinements a step further during lockdown.

Allan has been using the time on his indoor trainer to measure his sweat rate data by following the advice in our blog: how to measure your sweat rate and improve your hydration strategy.

Allan has kindly taken the time to detail his sweat rate testing process for us and outlined what he's learned...

 

Hi Allan, could you start by reminding us how you previously approached your hydration strategy for races?

I had been drinking to thirst for many years after I started triathlon in 2009. I became more certain that it was correct after reading the book Waterlogged by Tim Noakes.

In theory, it worked great for me. But that's only if I count the races with either short duration or very cold weather.

In hot conditions, I failed again and again. I started to believe that I just wasn't good in the heat, instead of looking at possible changeable reasons why I underperformed.

 

Allan Hovda on a bikeCredit: Allan Hovda ©

 

And so was it a case of learning through 'trial and error' to find out what worked for you in different conditions?

Yes, mostly through trial and error. What I wished I had done differently was to be structured when testing. If I had been, I would have actually known what worked and what didn't.

As I mentioned, I drank to thirst and sometimes it worked very well and other times it truly didn't.

Unfortunately, that strategy leaves you with no usable data to adjust.

 

So, moving things forward, why did you feel that calculating your sweat rate was important?

When I started measuring my sweat rate it became obvious why, in certain conditions, peak performance was impossible.

My sweat rate at IRONMAN intensity could differ from as little as 0.5 litres per hour in cold conditions, up to 2 litres per hour.

When the conditions are relatively cold I replace my lost fluid naturally by drinking to thirst, but when it's hot I'm miles away from taking on the fluid I need, even at lower intensities.

Recognising those facts was very useful for me as I now know when my natural feeling of drinking works well and when it doesn't.

 

And can you outline the process of how you go about measuring your sweat rate for us please? I think it's something athletes who are thinking of starting to measure their own sweat rate might find really useful...

  1. I weigh myself before and after the session
  2. I note my fluid intake (a water bottle with volume measurement comes in very handy)
  3. I note my food intake
  4. I note peeing, if any
  5. I note the intensity (watt/speed/HR)
  6. I note the duration
  7. I measure temperature and humidity
  8. I note if I used the big or small fan, or none
  9. I write a comment on the session

Instead of weighing myself without clothes (which can be impractical if you're training in a gym!) I know roughly the weight difference between my kit in dry and wet conditions (e.g. 0.1kg when cycling on the turbo and 0.3kg when running indoor on a treadmill. I insert that weight difference).

While it does look like a lot of work, it just takes a few minutes and most of it can be done while doing the session, particularly if you're doing it on a turbo.

I test my sweat rate nearly every turbo session at a different intensity or duration.

I just would add that I also write 'other conditions' (e.g. if done outside, I'll note whether it's cloudy or sunny, windy or still etc in the comments section).

Measure your sweat rate data spreadsheet

 

Allan Hovda's indoor training set upCredit: Allan Hovda ©

 

Fantastic. We know you're an athlete who looks at every finite detail of your performance and I'd be interested to know what you've learned from looking at your sweat rate and fluid intake in more detail?

What gets measured gets managed.

Looking at my fluid loss and intake made me drink more and helped me to be less dehydrated after sessions.

While they might not provide huge gains in the sessions themselves, they could help improve my recovery. 

I could see how beneficial that will be when the race is 8+ hours.

I must also add that I observed that drinking a sweet tasting drink, like water mixed with the PH powder or tablets, made me naturally drink more than just plain water.

For that reason, I will add a PH 1500 tablet to every 0.5 litres of water I grab at the aid stations during the bike.

 

And finally, what's been the most useful takeaway from doing sweat rate testing and how do you see it influencing your performance in races going forwards?

I'm absolutely certain I will perform more consistently in hotter conditions.

Now I will use the opportunities I have on the bike to drink more. I don't think it will improve my performance on the bike, but starting the run with 0 - 1 % dehydration will give me a much better chance of success than my typical 4 - 5 % dehydration I have started with in the past.

My sweat rate in Kona-conditions on the run would be around 2 litres per hour, and replacing that while running is impossible.

 

Allan Hovda on the indoor trainerCredit: Allan Hovda ©

 

Personally, I can handle around 5 - 6 % dehydration before my performance suffers so I need to have a solid buffer when I start running to avoid passing that point with a long way to the finish line.

I would also add that training works.

It sounds rather obvious, but I'm thinking specifically training the gut to tolerate fluid intake.

I was able to increase my fluid intake during hard running from 0.7 litres to 1.3 litres per hour, without feeling like I was drowning or that the fluid just splashed around in my stomach.

 

Thanks Allan, it's been great to get an insight into how our athletes are using their sweat rate data to improve their hydration strategy and performance. 

 

If you're interested in measuring your sweat rate, it will be worth checking out this blog.

And if you have any questions, please do email hello@precisionhydration.com and our team of Sweat Experts will be happy to help. 

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