Can heat stroke cause long-term performance problems for endurance athletes? Once an athlete suffers a bout of exertional heat illness, they’re then more susceptible to experiencing symptoms again and their performance may be impacted in future.
Pro triathlete Matt Hanson collapsed with heat stroke at IRONMAN® Texas in 2016, and went on to experience lasting physiological changes that made racing in hot and humid conditions significantly harder.
We spoke to Matt to find out how he coped with a massively increased sweat rate after the incident in Texas and how he's now able to perform in extreme heat...
Hi Matt, can you tell us about your experience at Texas in 2016 and the effect it had on your performance during the following years?
Well, I’ve raced IRONMAN® Texas a number of times. In 2015, things went pretty well - it was a really hot day and I ended up taking the win overall, almost as a virtue of being the last man standing in brutal conditions!
So, I came back in 2016 with high hopes, and was again well down the fiel when coming off the bike - like I had been the year before - I was running well and moved myself into a podium position.
With about 5k to go, I saw 2nd place in front of me, and said to myself, “I have one more push in me”. But my body said, “no, you don't”, and I went down with heat stroke.
The heat stroke didn't feel like it was taking too much of a toll in the following weeks, but I just couldn't get solid workouts in. I felt fine, but I couldn't push myself too hard in sessions. The long term effects were pretty intense. In races in high humidity, my sweat rate went from about 1.3 litres an hour to over 3 litres an hour.
I did sweat rate testing to replicate the IRONMAN® World Championship conditions in Kona by visiting the University of Connecticut heat lab and it was scary what level of fluid intake I would need to be successful on race day. For context, in 2018, I lost 22 pounds during the race and just couldn’t keep up with hydration.
So, how have you been able to get back on top of your hydration strategy and perform at your best?
So there was a long stretch where avoiding hot races was essential for my success, but with my main goals always being in Kona, I had to figure that out. I believe one of the biggest things that helped me was moving to altitude, and that’s potentially because a lot of the adaptations that you get at altitude are very similar to what you do during a heat prep.
So even though I was doing a heat prep leading into hot races, I think being at altitude helped me over time. And it was moving to altitude when I noticed that I was handling the hot and humid races much better again.
Thankfully, my sweat rate is down well off of what it was at the 3 litres. It's about half of that now. I have to do a lot more frequent testing just to have confidence that I know what I'm losing, and I try to do testing in conditions that are specific to race day. I still sweat a lot more if it's humid than if it's not, even if it's cooler, so there's just some defence mechanism in my body that notices the humidity a lot more than the dry heat.
As well as my sweat rate increasing, I obviously lose a lot of sodium too. So, on the bike, one of the big turning points was when I started taking the Electrolyte Capsules. I’d take two capsules an hour on the bike, and drink a Carb & Electrolyte Drink Mix as well, so I can get the carbohydrate intake up to the level I want.
I'm constantly managing osmolality so on hot or humid days, I have to cut the calories down a little bit in order to increase the sodium so I don't get gut issues. That means I have to be a little bit smarter on the intensity side of things and manage spikes a lot better, so I can try to manage carb intake a little bit.
Racing in Kona, I target three bottles an hour on the bike, and then as much as I possibly can on the run. It’s always hard to measure when you're running through aid stations in that heat, but, get as much as you possibly can in, listening to the gut.
What would be your best advice for an athlete who struggles in the heat?
My number one piece of advice if you're racing in hot conditions is to measure your sweat rate in similar conditions to what you're going to face on race day.
Reconfirm that in all of your sessions. Weigh yourself before and after; record everything you eat and drink, and try to simulate the race conditions as best you can, even if you have to overdress or hop in a sauna afterwards, just so you get that humidity stimulus.
The key is to learn as much about your body as you can, especially if you suffer from a heat-related illness that impacts your performance like I did.
