Hydration for Running

Hydration for Running

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Hydration. It is something that we all know is essential for ensuring high performance, especially when preparing for or participating in an endurance event, such as a marathon. It is also imperative for maintaining overall health. But how much do we actually need? And what should I be drinking?

Pre event hydration

Consume adequate fluid in the lead up days to your event. Drinking bottles and bottles the day before your event is not the same as having an adequate fluid intake on a regular basis.

Prior to event, aim to consume 300-600mL with your pre event meal, and then 300-450mL 15-20mins before the event. You will need to experiment to determine exactly how much you can tolerate, make sure you do this in training.

For shorter events, water is fine. For longer ones, use of sports drinks can be an easy way of topping up on carbohydrate and electrolytes, as well as fluid. Make sure you rinse your mouth after consuming sports drinks (where possible) as they are horrible for teeth!

During the event

Once you start doing longer distances, it is advisable you take fluid with you to ensure you stay hydrated, or at the very least make sure your path has plenty of water fountains. It is individual what you choose to take, but for most training where you are using gels, water should be sufficient. If you are unsure, make sure you check with your Sports Dietitian.

On race day there will usually be fluid stations supplied, where you can choose to have either sports drink or water, but still wise to take water with you if that is how you train.

Key thing to remember? Do what you would normally do; if you have never tried sports drink during a run, it is best not to do it race day, as you may not know how your stomach will react. The last thing you want is runners gut!


The best way of working out how much fluid to consume after your event is to weigh yourself before and after your run, whilst wearing minimal clothing and holding your drink bottle/camelpack (filled at the start, and with whatever is left afterwards). You need to rehydrate 125-150% of this, ie for every 1kg you lose, you need to drink 1.25-1.5L of fluid. You don’t need to guzzle this straight away, but finishing it off over the next 3-4 hours is important. Remember you’re not fully rehydrated unless your electrolytes have also been replaced- this is especially important on longer runs, so make sure they are included in your recovery plan somehow. See here for some ideas.

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