Hydration: 5 mistakes triathletes make and how to avoid them

Hydration should be easy, right? You get thirsty, you drink something. But if it's really that simple, why do so many athletes come unstuck with hydration-related issues during races and training? Andy Blow explains the common mistakes and how to fix them


This list highlights 5 of the more common mistakes athletes make with their hydration, to help you become better equipped to avoid them in the future yourself.


1. Don’t drink too much

 Whether it’s because of nerves, an irrationally strong fear of becoming dehydrated, or more likely a bit of both, over-drinking is a surprisingly common problem for endurance athletes, especially in the build up to big races. And, in some cases, it can actually be quite harmful to health and performance.

Adequate hydration is, of course, necessary if you want to perform at your best. But there’s a limit to how much fluid the body can store once you’re topped up. If you keep on drinking beyond what you need (especially if it’s plain water or other low sodium fluids) the body’s first line of defence is to make you pee more to dump the excess. As this happens you start to lose electrolytes with the fluid (sodium in particular) and if this goes on for long enough it can cause problems, especially in long duration activities where you also lose a lot of electrolytes through sweating.

What can be even worse is if you over drink to the extent that it overwhelms your ability to pee (and sweat) out the excess, and fluid starts to build up in the body. This causes bloating, nausea, dilution of your blood sodium levels and eventually a nasty condition called hyponatremia if it goes on long enough.

Mild hyponatremia will at best just ruin your performance, but at the extreme it can lead to coma or even death if it goes unchecked, and this has happened to a number of unfortunate endurance athletes in recent years. If you think it’s not all that common you’re mistaken too; over 10% of the field at the European Ironman championships have been shown to routinely finish with mild hyponatremia in recent years!

Hyponatremia: What it is and how you can avoid it

Hyponatremia: causes and symptoms of low sodium levels

That’s why drinking too much is probably the number 1 hydration mistake you should aim to avoid as an endurance athlete.

2. Don’t drink too little

At the other end of the scale it is of course more than possible to under consume fluids, and this is not good for you either. Ultimately, dehydration beyond a certain point is definitely harmful to performance. Although many are very frightened of any level of dehydration, incidences of it happening in training and in races to a severe extent are probably much less common than you might imagine. This is in part because during many races and training sessions athletes tend to have free access to adequate amounts of water or sports drinks and can top up whenever they feel like they need it.

Despite the bashing it has had from some scientists in the past, thirst is actually a pretty good mechanism for telling you when you need to drink. So, as long as you drink enough to prevent significant thirst (as people almost always tend to when they have free access to water), you’re unlikely to fall well short of meeting your low-end fluid requirements at the very least.

There are exceptions though and clearly athletes do become dehydrated at times and this can happen for a few different reasons:

* Running out of fluids. If you don’t take enough drinks out on a session or race and don’t have much access to get re-supplied, then there is always the risk of being caught short. This is all about planning ahead to avoid it being an issue.

* Starting a session or race already a bit low on fluid. Again this is due to poor planning or preparation, so taking care to get your pre-event or workout hydration strategy worked out is a good idea to avoid this pitfall.

* Novices athletes failing to listen to their body properly.  Whilst pretty much all of us would respond to severe thirst by drinking a lot, novice athletes don’t tend to know their bodies quite as well as those with more experience. They are therefore more likely to miss the early signs of dehydration/thirst when focussed on other pressing matters in a race and end up in a situation where they get too low on fluids without realising it and can’t easily correct the problem before it is too late.

* At times when sweat rates are excessive. Sometimes, either because of very hot environmental conditions, a high work rate or just because they naturally have an extremely high sweat rate, athletes can lose fluids much faster than they can absorb them, even if they drink a lot. In these circumstances dehydration, to a degree, is an inevitable consequence of exercise and can be a limiting factor on how long and hard you can go on for.

Ultimately, the best way to avoid under consuming fluids is to use a combination of conscious and instinctive measures to do so…

* Drink to thirst when you know you can rely on it. If you’re a novice, be consciously aware to check in with yourself to assess the level of thirst you have on a regular basis during long sessions or races.

* Check your pee. If you’re peeing infrequently and it’s dark in colour, that’s a sign you are becoming dehydrated so you probably need to increase fluid intake. However if you are peeing a lot and it’s always very clear you may be drinking too much, so be prepared to back off.

* Monitor changes in your body weight. During periods of very heavy training it can be useful to check your morning resting bodyweight each day, immediately after getting out of bed and before you eat, drink or pee. If you are more than about 1.5% lighter than the day before (and especially if you are thirsty and your pee is quite dark too), it’s a good indication you’re in negative fluid balance and should think about topping up a bit more that day.

* Learn from experience. Be diligent in checking how much to actually drink in key training sessions and races and compare that with performance, recovery rates and subjective feelings of hydration status so that you learn to become more in tune with your body’s own needs as time goes on.

3. Avoid drinks with too much carbohydrate in them

Many sports drinks are designed to fulfil two basic roles for athletes; to provide fluids (+ electrolytes) and carbohydrates to combat dehydration and glycogen depletion.

Lots of research has been done on various different types of drinks to determine the optimal balance for delivery of fluids and carbs into the body, but the big issue is that the levels are very different depending on what you’re trying to achieve. At one end if you are trying to deliver energy to working muscles, drinks with 8, 10 or an even higher % carbohydrate can do a great job.

However, to maximise fluid absorption in the gut, something much lighter (around a 3% carb solution) is needed. Issues start to arise when athletes try to hydrate in large quantities with strong (6% or more) carbohydrate drinks and especially when they also add other carbs into the stomach at the same time in the form of energy bars and gels. This ultimately creates a super-sickly sugary concentration in the stomach leading to slower fluid absorption, gastric upset and nausea.

The other way that the strength of drinks can cause issues is when athletes use powdered formulations to mix up their own bottles, and try to add more powder than is recommended to a set volume of water. This obviously results in a much thicker, more sugary solution than the manufacturers intended and can cause gastric issues if consumed in large quantities.

4. Neglecting electrolytes (when you probably need them)

Electrolytes can play a key role in helping you hydrate effectively when sweating during training and races, but only if you use them as and when they are actually required.

In terms of which electrolytes you need, sodium is really the only one that matters when it comes to hydration, as  both your sweat (that you’re looking to replace) and blood stream (that you are aiming to top up) are very salty. They also contain very small amounts of potassium, calcium and magnesium so the requirement for those is minimal.

People lose sodium in their sweat at vastly different rates to one another due to genetics and differences in overall sweat volume loss. As a rule of thumb (and as long as you start well hydrated), most activities below 90min shouldn’t require much if anything in the way of sodium replacement. However when you start to go above this threshold (and certainly if you are a ‘salty sweater’ – i.e. you lose a high amount of sodium in your sweat), or if you just have a high sweat rate, adding sodium into your drinks is likely to be beneficial.

Sweat testing for athletes: is it worth it?

And the benefits of electrolyte supplementation increase as the duration of activities and total sweat output increases. The key thing with electrolyte replacement is to have a good idea of what your losses are likely to be so you can experiment with different ratios of fluid and sodium to meet your individual needs in different situations.

Dehydration and sodium: why replacing salt is crucial

5. Avoid too many drinks at the post-race party

People get more drunk, more quickly when they’re not used to drinking alcohol and when they’re dehydrated (low levels of total body water mean the alcohol is diluted down to a lesser extent so has a more potent effect). This means that drinking heavily at the post race party after a period of abstinence from the booze, combined with some lingering dehydration from the event itself is a perfect recipe for total disaster!

I’ve personally seen some of the worst dance moves ever witnessed (much more incriminating than at even the most horrible family wedding party) at post race awards evenings. I therefore strongly advocate drinking in moderation the night immediately after any big event. And, should it be needed the prevalence of camera phones and social media sites to post footage on these days should only provide added motivation to adhere to this strategy…

This article is part of our series on common training mistakes triathletes make

Andy is a regular contributor to 220 and you can subscribe to 220 Triathlon magazine here

Andy Blow has a few top 10 Ironman and 70.3 finishes and an Xterra World Age Group title to his name. He founded Precision Hydration to help athletes solve their hydration issues and you can take their free online Sweat Test to get started with your hydration strategy today. He has a degree in Sport and Exercise Science and was once the Team Sports Scientist for Benetton and Renault F1 teams.



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