Hydration for an IRONMAN
If you read last week’s blog you will already understand the importance of staying hydrated during your event. Dehydration and sodium loss through sweating can severely hamper performance if you do not keep on top of your hydration. In shorter events you are unlikely to sweat enough to limit your performance, so drinking to thirst is likely to keep your fluid and sodium levels topped up. However, in lengthy endurance events like an IRONMAN fluid and sodium loss will be much higher. According to a 2015 study, athletes who adequately replaced the sodium lost in their sweat finished a middle distance triathlon an average of 26 minutes faster than those who didn’t. This study highlights how important it is to think about hydration before you get to the start line of your next IRONMAN!
Last week’s article described the importance of understanding your personal sweat rate and sweat sodium concentration to tailor your own hydration strategy. The results of these tests will dictate the strength of the electrolyte product best suited to your needs during your event. Most electrolyte products only offer 200-500mg of sodium per litre, if the above tests indicate that you are a particularly salty sweater or you have a high sweat rate, you could try a stronger electrolyte product. (Precision Hydration offer: 500, 1000 and 1500mg of sodium in their products).
[When I had my sweat tested by PH, I discovered the cramps I normally suffer in long events were probably due to my incredibly high sweat sodium concentration of 1924mg per litre. I have now switched to drinking PH1500 and have not suffered any cramps since]
Before
For an IRONMAN, Precision Hydration highly recommend ‘preloading’ your hydration, especially if you will be racing in the heat. This involves drinking a strong electrolyte drink (strength tailored to your needs) the night before your event and 90 minutes before the start of your IRONMAN. Make sure you stop drinking 45 minutes before race-start to allow your body to absorb the fluid. Don’t drink any additional plain water to avoid overhydration and dilution of the sodium in your blood. Studies show this preloading technique will give your body a head start, it will increase blood plasma volume, making your cardiovascular system more efficient at delivering oxygen and cooling your body, before you even start sweating.
During
For those that have already completed an IRONMAN, you will know the importance of the bike leg for fuelling the body for the run, the same is true for hydration. It is much easier to drink on the bike leg than the swim and run legs! It is important to keep on top of your hydration on the bike leg so that you arrive ready to run the marathon rather than survive the marathon. Again, use your personal sweat rate and sweat sodium concentration to dictate the strength of the electrolyte product you choose to take on the bike. How much you drink depends on your sweat rate, the temperature, humidity and the amount of fluid your body can process. Most athletes will need to take in 600ml-1litre of electrolyte per hour on the bike. On the bike, pay attention to clues that you may be under hydrating - dry-mouth, feeling thirsty and not needing to pee at least once. Similarly, if you can feel fluid sloshing around in your stomach or need to pee more than 3 times during the bike leg you have probably taken on too much.
Once you hit the run it is a lot harder to hydrate, hence the importance of hydrating well on the bike. If you are feeling very thirsty, it is much better to slow down and walk through the aid stations to make sure you can drink enough fluid. If it is hot, cooling strategies like wet sponges or ice on your head or in your hands can help lower your core body temperature, decreasing your body's need to sweat, which in turn helps reduce dehydration. Depending on your sweat characteristics salt capsules may be a good idea for you on the run as a convenient method of keeping electrolytes topped up.
After
It is impossible to replace all of the fluid lost during an IRONMAN and would be dangerous to try, due to overhydration and potential hyponatraemia. Therefore, to aid your recovery it would be advisable to sip a strong electrolyte drink in the first 2 hours post-IRONMAN to bring your blood volume back up. Non-alcoholic beer (or alcoholic, why not!) is the perfect post IRONMAN isotonic beverage!
As with race-day nutrition, you must try out your hydration strategy before race day, try different products, try different strategies and see what works best for you. If you need any more advice on how to prepare your IRONMAN hydration plan your TTH coach will be more than happy to help.
We’re here to help
Tri Training Harder are one of the leading Triathlon coaching providers in the UK, using our wealth of experience to unite scientific and technological research with already well-established and successful best practices, to create a formula for triathlon and endurance coaching that works.
The result is an honest, dynamic, yet simple new way of constructing an athlete’s training to allow them to reach their potential.
If you’re planning your next season, just starting out in the sport or are looking for extra guidance at the very top end of the field, we are here to help, and our coaches would be delighted to hear from you. You can contact us via the website, and one of the team will be in touch.