Brazil Ironman Triathlon Hydration

by Chris Park

As a hypothetical sports nutritionist and triathlon coach, I have a few questions that I could use a little help with;

1. Given the conditions in Brazil at the time of the Brazil Ironman, what type of fatigue do you think my athlete will experience and how will this affect performance?

2. What fluid intake precautions should my athlete take in the hours prior to the event given the conditions during the triathlon?

3. Would the fluid intake prior to the triathlon have any influence on my athlete’s carbohydrate availability during the event?

4. How can my athlete offset the effects of dehydration during the event, can you give me specific guidelines?

5. What are the best recommendations for restoring body fluid stores after training in the weeks leading up to the event?

Intelligent Triathlon Training replies:

It appears that average weather conditions in May in Florianopolis for the Brazil Ironman are temperatures of around 22 – 25C, with humidity being the key factor, ranging from 62 – 98%.

1) It really depends on how the athlete races and their nutritional strategy. The weather conditions are irrelevant if your athlete races at the appropriate intensity for their fitness and has a good nutritional strategy. Intensity in an Ironman is relatively low and if the weather conditions are as above, core temperature should not rise excessively.

2) The athlete needs to start the race fully hydrated, but not over hydrated as this does not provide any benefits, and hyper-hydration can lead to more problems than it solves. Given that the race probably starts very early in the morning, you would want your athlete to wake up and for their first pee to indicate that they are well hydrated (pale straw coloured). Therefore the day before it is important to maintain fluid balance by drinking enough to replace what they sweat, particularly if exercising. But they don’t need to drink excessively – use thirst as a guide. They might want to use rehydration tablets in some of their drinks.

3) No, nothing worth worrying about!

4) The athlete does not need to replace everything they lose – they will finish the race dehydrated, which is normal. The best guide is to drink to thirst. If they are a salty sweater, that salt needs to be replaced, through drinks with rehydration tablets/sodium. A salty sweater will have salt crystals on their skin when the sweat dries. Ensure that some drinks contain carbohydrates. For a 75kg person, in those conditions they could lose between 500 – 1250ml per hour (more in the run than the bike), so they should be aiming to replace about two thirds of this.

5) Weighing before and after sessions gives an indication of fluid loss. Conventional guidelines suggest that you should aim to drink 1.5 times this to fully rehydrate but recent research indicates it may not be necessary to consume this much. Including sodium in post-training drinks encourages fluid consumption and also replaces electrolytes lost through sweat.

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