Nutrition and hydration are some of the key elements that impact performance in endurance sport, and yet are often the least understood by many athletes.
In this piece, Andy Blow – founder of Precision Hydration – provides a very practical guide to keeping hydrated during Sprint and Olympic distance races.
Let’s talk about dehydration
Hydration is as a crucial factor influencing performance in endurance sports like triathlon. Significant fluid loss is proven to negatively impact endurance performance, so avoiding getting excessively dehydrated when you’re racing is clearly very important.
However, what constitutes ‘significant’ dehydration and whether it’s realistically likely to occur during a short course triathlon is a matter of some debate.
Nearly all athletes finish endurance events dehydrated to some extent, this is normal and to be expected. However for performance limiting dehydration to occur, most people need to lose at least ~2% of their bodyweight in fluid, assuming they start exercising in an optimally hydrated state (or ‘euhydrated’, to use the scientific term).
There’s evidence that some athletes can also tolerate much more than 2% dehydration and still perform at a high level, so that number is certainly not set in stone. It’s just the likely starting point for when problems could occur.
To put this figure into context, 2% of the bodyweight of a 70kg (11 stone) person is 1.4kg. As sweat weighs about 1kg per litre that equates to about 1.4l of un-replaced sweat losses as the likely starting point for performance issues that could be pinned on dehydration.
Human sweat rates vary wildly from person to person, from less than 500ml/hr to over 3.5l/hr in extreme cases, but as an average something around 1-1.5l per hour is considered pretty normal in healthy adults.
How to stay hydrated during a Sprint distance triathlon
Because your total fluid losses are likely to be moderate at worst, then drinking much if anything at all during the race itself is unlikely to offer major gains (if any at all), assuming of course you toe the start line well hydrated to begin with.
This doesn’t mean that you should actively try to do a Sprint tri without drinking. Having a bottle on your bike adds little to the overall weight in the grand scheme of things and having the ability to quench your thirst on the ride may well be of actual benefit, especially if the conditions are hot.
However, it’s unlikely you’re going to need more than one small bottle and if you don’t feel like drinking it all as the race goes on then there’s no need to force it down the hatch, risking an upset or bloated stomach on the run.
If you’re out on the course for significantly longer than 60 minutes, then you’ll likely still be fine sipping from a single bottle on the bike ride and possibly wetting your whistle with a cup or two of water from an aid station on the run. However the key thing is to learn to listen to your body on that and drink to the dictates of thirst.
The bottom line for Sprint triathlons is that as long as you deliver yourself to the start line well hydrated then fluid loss is almost certainly not going to be a major performance limiting factor on race day.
How to stay hydrated during an Olympic distance triathlon
When stepping up to the Olympic distance things have the potential to get a little bit more intricate. All of a sudden race duration doubles up to around two hours for the fastest athletes, and can be closer to three+ for many.
If conditions are hot, you’re working hard and have a high sweat rate, seeing total sweat losses of five litres or more is definitely not pie in the sky during an Olympic triathlon.
For a 70kg athlete, five litres of sweat loss equates to more like 7% dehydration and it would be reasonable to assume that this would cause some pretty significant performance decline in most cases.
Because of this increased potential for significant dehydration, it’s very rare to find athletes who do an Olympic distance race without drinking at all. Many will sensibly use the time on the bike to get at least some fluids in. Both carrying a drink and consuming it is way easier on the bike versus the run.
Anything from around 400ml to 1000ml during the ride would be a sensible amount to have available. The lesser amount would apply if you know from past experience you’re not a big drinker/heavy sweater. If it’s extremely hot or you just know you have a high sweat rate to compensate for, you’ll likely need closer to one litre.
As with Sprint races, it’s still generally a smart idea to listen to your body on the day to determine the exact amount to drink. The main difference is that in an Olympic distance race you want to be of a mindset that you’ll definitely be drinking a reasonable amount rather than just seeing if you can get away with nothing at all.
As long as you’re tuned into your own thirst cues and don’t have a history of ‘forgetting to drink’ too often, using your instincts will help self-regulate intake and stop you from significantly over or under doing it.
What should you drink during a short course triathlon?
During long course races the primary aim of drinking should be to replace fluid and electrolyte losses and it’s common to expect to get the lion’s share of calories from solid (or semi solid) foods like energy bars, chews and gels. This approach tends to help replace higher sweat losses more closely and gives rise to less stomach issues than using the more sugary energy drinks. This will be the topic of a future article here on Tri247, so look out for that in the coming weeks.
For short course events a stronger case can be made for drinking something that contains carbohydrate calories as well as electrolytes. That’s because the calories in these drinks are very rapidly absorbed into the bloodstream and therefore help maintain blood sugar levels very effectively. All of this is a big topic and actually the subject of a piece I wrote recently if you want to dig into it in more detail.
Don’t mess up your pre-race hydration
The question of what to drink BEFORE a short course triathlon event is extremely important, but ironically often overlooked.
This is because starting well hydrated gives you an optimal reservoir of fluid to expend in sweat. Many athletes know this so they try to ‘load up’ in the final few days by consuming a lot of extra water.
The big problem with dramatically increasing your water intake in the final few days before a race is that, as humans are not camels, you inevitably end up having to get rid of nearly all of the extra fluid consumed through numerous trips the bathroom! As you lose electrolytes when you pee, this process actually lowers your body’s sodium levels and this can hurt performance (and in the extreme make you quite ill) through a condition called hyponatremia.
It’s a much better idea to ‘preload’ with a modest amount of a very strong sodium-based electrolyte drink. This works because the extra sodium in the fluid is absorbed into your bloodstream via your gut. The sodium pulls water with it on this journey, holding it in your blood plasma rather than causing your kidneys to pee it out.
We recommend using something like PH1500 for this purpose as it contains 3x the electrolytes of a typical sports drink. Aim to take in ~500ml the night before and another ~500ml about 90 minutes before you start the race. That’s usually plenty to top up your tanks, without causing unwanted trips to the bathroom. By following this protocol you maximise your chances of being optimally hydrated on the start line.
How to speed up your recovery after a short course triathlon
You will very likely finish a short course race somewhat dehydrated, so getting your body fluid levels back up is an important part of the recovery process. All available research points to the fact that drinking fluids containing sodium is the best way to do this.
Using something like PH1500 is a good idea to replenish what you’ve lost. You can also be pretty liberal with the salt shaker during your celebratory fish and chips ‘recovery meal’!
- Start well hydrated. This doesn’t mean lots and lots of extra water pre-race! Instead, use a very strong electrolyte drink the night before and morning of a race to ‘top off’ fluid and blood electrolyte levels.
- Have drinks available on the bike but don’t force yourself to drink more than you feel you need, especially during Sprint races. Listen to your body and base your drinking regime on instincts and experience for best effect.
- Post-race recovery is enhanced by restoring your body fluid balance relatively quickly. Replacing both fluids and sodium together in significant quantities is more effective than just drinking lots of water alone.
Keep your eyes peeled for the next post in this series where we’ll cover how to stay hydrated during middle and long distance triathlons.
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. He has a degree in Sport and Exercise Science and was once the Team Sports Scientist for Benetton and Renault F1 teams.