Faversham Running Club England Athletics
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Hydration and running

by Lil Diamond

I don't sweat, I glisten

Dehydration is really common in running, especially in longer events. It also significantly impairs performance. Getting your hydration right during training runs and in events is a simple thing that can help improve your performance.

When we run, we sweat; everyone is different and some people will sweat more than others. The hotter it is or the harder you work, the more you sweat. This is the body’s way of stopping you from overheating. 

In typical temperatures of 15-20 °C you can lose 800-1200ml of fluid per hour just in sweat!

Top Tips for keeping hydrated

Start a run hydrated

Aim to start a run hydrated, by drinking water or a sports drink regularly in the few hours before. Sip it over time rather than having lots at once. This helps the fluid get into your cells and helps avoid the need for a toilet stop! Aim for straw coloured wee.

Replace the fluid you loose

Aim to replace the fluid you loose through sweating, but don’t take on too much. You can estimate the amount of sweat you lose by weighing yourself before and after an hour long run (without drinking anything during your run). 1kg = 1litre of fluid. So, if you weigh 72kg before and 71kg after your run, then you have lost 1litre of fluid over that time. This will give you an idea of the amount of fluid you need to aim to get in when you run in similar conditions.

Energy and fluids

If running for more than 1 hour, you can try using drinks that contain sugar/glucose. This can be a useful way of getting in the energy and fluid you need all at once.

Long runs

If running for more than 2 hours, you will need to think about using a drink that contains electrolytes or ‘salts’, like potassium and sodium. Our bodies need electrolytes to function and they are also lost in sweat – this is why your sweat is salty! You can buy ready-made or powdered sports drinks which contain electrolytes (look out for ‘hypertonic’ or ‘electrolyte’ drinks). Some runners completing long runs keep a bottle of water for the first hour or so and then move on to an electrolyte drink. As with everything, try different products to see what agrees with you.

Feeling thirsty

Do not be led by thirst alone and aim for regular fluid, if you go by thirst, you may underestimate how much fluid you need.

Too much fluid

It’s really important you also do not go overboard with the fluid and take on too much.


Carry on drinking a sports drink and then water regularly after a long event – it can take 12 hours for your hydration to return to normal after a marathon!

If you try and be mindful of how you fuel your body, I promise, with training, you will be amazed at what your body can achieve!

Elizabeth (Lil) Diamond
Event hydration

I know loads of runners avoid drinking as they want to avoid toilet breaks and don’t like carrying anything! Try a little and often approach and experiment with different water bottles or hydration packs. Chat to club members to see what they recommend.  If you don’t normally hydrate when running over an hour, try building up slowly and incorporate it into your training and plan for events. It also goes without saying that as the temperature rises and you sweat more, you will need more fluid than normal.

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