The importance of starting hydrated

The importance of starting hydrated


It's so easy to simply think about the day of your event and focusing on getting it right on the day. However, your performance is absolutely influenced by how well hydrated you are before you start your session or get to the start line of an event.

Why? Well because once you've started you're going to fight to replace all the salts and electrolytes, so it's best to give your body a decent head start. In this blog I'll share what I've learnt about starting hydrated and how I've put that into practice. 

Blog 1 of 3 in a #ThirstyThursday series by #TeamKMC and ultra-cyclist Guy Stapleford.


If I've got a long, high intensity training session or a race then I'll pre-load my system the evening before. Pre-loading is basically drinking electrolytes before your session in order to optimise your hydration status. There's some sense to it, being properly hydrated means your body has a larger pool of fluid to draw from over your session than if you start dehydrated. Not just that, there are other benefits too, from promoting acute fluid retention, improving performance and maximising your blood volume, which generally helps your cardiovascular system and your ability to dissipate the heat generated by your muscles.

When I took on the Sufferfest Knighthood and vRAW in 2020 I had really started to think about hydration a lot more, largely because I knew that these two indoor challenges - 10hrs of back to back workouts and 950miles as fast as possible respectively, meant I was going to be sweating buckets. I read a lot and also completed the 'Science of Endurance Hydration', a course from the TrainingPeaks University. It's well worth the investment, as it covers a lot of the science and translates that far better than I can here. 

The science-ish

So after graduating from the sweat university I set about creating my hydration strategy, the first step of which is to calculate how much I sweat and therefore how much electrolytes to take on, being a heavy / salty sweater!

Simply drinking more water before an event or training session is not the whole answer. It is not just how much water you drink, but with how much sodium you consume with it that's important. It's this electrolyte that plays a key role in retention of fluid in the body and in the bloodstream in particular.

Drinking too much plain water before means you can end up diluting your body's sodium levels and run the risk of getting hyponatremia during long & multi day races. Obviously this is severe and a worst case, but keeping hydrated means you'll reduce fatigue, remain focused and reduce the chances of sickness or GI issues.

Electrolyte tablets and drinks aren't to be mistaken for fuel as most will contain barely any calories or carbohydrates. The main aim of them is simply to aid your hydration, replacing salts lost through sweat as well as helping the body to take fluids into our systems better than water alone.

It's worth experimenting to find what works for you but a good rule of thumb being 1,500mg of sodium per litre of water is a good sweet spot. I'll aim to have a drink with 1,500mg in 500ml of water the evening before my high intensity training sessions or events and then the same again around 90minutes before the start - this gives my body time to absorb what it needs and nervously wee out the rest before I get going.

3 Takeaway tips

  • The night before, drink 500ml of water with between 750mg and 1,500mg of sodium.
  • The next morning, 90 minutes before you start, drink the same amount of water and sodium as the night before.
  • Aim to finish this bottle about 45 minutes before the race, to allow you time to get rid of any excess fluids your body hasn't absorbed. 

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The importance of starting hydrated