Most triathletes understand that being well hydrated is important if you want to perform at your best, especially during longer races and when it’s hot. But, exactly what being ‘well hydrated’ really means and, more importantly, how to ensure you fall into that category when it counts is not as well understood. So, here’s some tips to help you make sure you’re hydrated when you get to that start line…

Image credit: Brad Williams via FinisherPix ©.

What does it mean to be ‘well hydrated’?

Hydration is all about balance.

Being significantly dehydrated can lead to poor performance, but over-hydration can also be very, very bad news, and this is much less talked about. Dehydration has received more than it’s fair share of bad press over the years. So much so that over-consumption of fluids before and during events is incredibly common.

This is potentially very dangerous.

It can lead to a condition called hyponatremia, which is caused by the dilution of the body’s electrolytes when too much fluid is taken in during a short period of time. Left unchecked, hyponatremia can be fatal. Sadly, it has killed a number of competitors in marathon and triathlon events, with one recent tragedy occurring at Ironman Frankfurt. Even if it doesn’t kill you, a mild case of hyponatremia can ruin your race, through debilitating symptoms like headaches, lethargy, cramps and sickness.

The aim of your hydration strategy is to achieve an optimal balance of fluids and electrolytes before getting to the start line. You then want to take in just the right amount of fluid and electrolytes during the race to minimise the negative effects of dehydration without over-doing it and running the risk of dilution and hyponatremia.

How do I start hydrated?

  • In general, listen to your body and drink largely to thirst. This means not allowing yourself to become really thirsty before you drink, but also not just gulping back water for the sake of it. It’s tempting to dramatically ramp up fluid consumption before a big race ‘just to be sure’. But that’s not helpful, resist the temptation!
  • Keep an eye on the colour of your urine and how often you’re peeing. If you’re going infrequently (only 2-3 times a day) and your pee is quite dark and low in volume, it’s highly likely you’re a bit dehydrated and should increase the amount you’re drinking. If, you're peeing more than 8 times per day, the pee is clear and there’s a lot of it, you could well be over doing it and should dial your consumption back a bit. Everyone is different, but peeing 5-7 times per day, with the urine a pale but slightly yellowy colour is generally considered ‘normal’.
  • Whilst people respond differently to their effects, it’s a good idea to minimise consumption of caffeine and alcohol a few days before your race.
  • Increase your sodium intake during the final 2-3 days before your race. This can be done by adding salt to your food or by swapping some of the plain water you’d normally be taking in with electrolyte drinks. Sodium is the key electrolyte associated with hydration (and here's a blog we wrote specifically about why sodium is so important for athletes). Increased sodium consumption boosts the amount of fluid held in the bloodstream and reduces the amount you have to pee out.
  • Pre-load a few hours before the start of the race with a 500-750ml dose of a very strong electrolyte drink (1500mg of sodium per litre or more). Studies have shown this can boost endurance performance as it expands blood volume and therefore reduces cardiovascular strain. Here's a bit more on the science of preloading if you're interested. It's is something you can try out in minor races or before very hard training sessions to see if it might work for you in your more important events. It is likely to be most beneficial when the you’re racing in hot climate, or if you're someone whose sweat and/or sodium losses are just generally very high.

How do I stay hydrated during the race?

  • For short races up to about 90min, drinking is unlikely to be necessary other than to stop your mouth from drying out. Just having a small bottle of water on your bike to sip from, and possibly grabbing a cup from an aid station on the run, is normally all you really need to do. You will lose fluid through sweating, but can easily rehydrate to replace any fluid lost post race and the low level of dehydration you’ll likely suffer will not be enough to impact your performance. Of course, If you do get thirsty, don’t ignore it and deliberately not drink, just don’t expect to need to be guzzling down much if your pre-race prep has gone to plan.
  • During events over 90 minutes the need for fluids starts to become apparent for most people and the amount required is largely driven by your sweat rate. This can vary dramatically from person to person and race to race depending on the intensity, weather conditions and individual genetic factors. Because of this huge variability in sweat losses any ‘one-size-fits all’ recommendation on how much to drink is not actually likely to work for everyone so should be treated with suspicion.
  • As with pre-race hydration, learning to listen to your body and drinking to the early signs of thirst are generally a good idea when the race is underway. However this approach alone requires you to be quite ‘in tune’ with your body. To help with that, here are some rule of thumb guidelines to help you gauge if you're taking in roughly the right amount per hour:

1. In cool conditions, or when you’ll only be sweating lightly, up to 500ml (16oz) of fluid should be sufficient for most people.

2. In warmer conditions and/or when you’ll be sweating more heavily, up to 750ml (26oz) might be needed.

3. In very hot or humid conditions and/or when you’ll be sweating a lot, you may find you need as much as 1 litre per hour of activity. It is worth bearing in mind that 1 litre (32oz) per hour is approaching the maximum anyone can usually absorb when exercising hard, so it’s unlikely you’ll benefit from trying to take in a lot more than that, unless previous experience tells you otherwise.

We've written about how much dehydration you can tolerate before your performance starts to suffer and remember it's definitely not a game of who can eat and drink the most. You do not need to replace 100% of what you lose. The aim of the game is to supplement as little as possible but still be performing your best when you cross the finish line.

  • Adding sodium to the fluids you’re consuming starts to become increasingly important when the duration gets long (2 hours or more) and the overall volume of sweat lost is getting quite high. This applies for some hot Olympic distance races and definitely for 70.3/Half Ironman events. During very long races, especially those in the heat, where total sweat losses can be massive over a period of many hours, personalised sodium supplementation starts to become critical, especially if you're someone with a high sweat rate and/or high sweat sodium levels.

Investigating your personal needs is a very good idea if you're signing up for any long course race and you can get an idea of what they might be taking our free Online Sweat Test

Further Reading