Hydrating for a Marathon

Get the message - Water is crucial. Even more crucial to those of us who are planning to spend 4 hours or more running around York and its suburbs in October.

• During a marathon, even with taking on fluids during the race, it is not uncommon to loose 6% of body water.

• A 2% drop in hydration increases heart rate and core temperature. This is not conducive to running.

• A 5% drop in hydration status can reduce your aerobic capacity by 30% and we really don’t want to do that as this is the energy system we are relying on in distance running

I cannot stress enough getting your Hydration right is a fundamental part of your training, you need to practice it and have a plan of how you are going to hydrate during your run.

So we need to be thinking about when to take on water, when to take on fuel (I will come on to this is my next blog) all the time, before training, during training, after training, and the same goes for the race. Start practicing now!

These quantities are a rough guide to aim for:

• 2 hours before you run: 500ml – sipped gradually over ½ hour or more

• 20 mins before a run: 200ml, again sipped – NOT glugged!

• Every 20 mins during the run: 200ml – on warm days 250ml, again sipping this over time – or with gel / fuel is best

• Don’t become besotted with it – just practice during training.

Take the Pee Test! If you are sufficiently hydrated your urine should be clear or light straw like in colour. Dehydration would show stronger yellow colour and stronger odour.

During the Marathon

There will be plenty of water stations, one great tip I was told was to not aim for the first person offering water – the stations last for quite a long way and if you get in the initial ‘queue’ you may have to stop. This will make it hard to start again!

Don’t panic - run past the first few then dip in – arm stretched out to indicate you would like a bottle – volunteers are fantastic and will do what they can to make sure you get a bottle – then cheer you on your way!

Now take the water just a little bit at a time. In the later stages of the run if you take on too much at a time it may make you feel sick as your stomach has shut down to let the blood go to your muscles, small mouthfuls are better; if you are having gel / fuel then intersperse with water (again I will highlight this in my next blog).

Some people find it very hard to run and drink – this is something you have to get used to, its just takes practice. On your long runs carry water and learn to take a sip on a regular basis. As a rule of thumb: think that if you are thirsty it is too late, you are already becoming dehydrated.

On the flip side – you can drink too much! Oh this is hard this isn’t it? Over hydrating can lead to Hyponatremia, causing dizziness, nausea and disorientation, yet again, not great for long distance runners! The key is to try it out during training, especially on your long runs 6 weeks or so before the marathon, then stick with what you know works for you on the day.

I find that I drink little and often, this works for me – but it does mean I will carry a bottle for a mile or so, almost protectively!

I also need to wash gel down with water so I am a bit loath to let go of a bottle until I know the next water station is in sight, which is a bit ridiculous as I am throwing away one bottle for another! So try to get a balance, being aware of your hydration during training and particularly the week before the marathon will mean a lot.

Sports Drinks
These will be handed out during the Marathon

Sports drinks are designed to give energy as well as hydrate. Do NOT solely take on board sports drinks.

One of the reasons why sports drinks are effective is that their composition is very similar to that of our body fluids including the electrolytes. Running for over an hour especially in warm weather increases loss of electrolytes through sweating. In order to help sugar absorption there should be electrolytes present, these help to maintain salt in the blood stream.

In order for fluid to be absorbed into the blood stream a sports drink must be isotonic. This means they should contain a similar concentration of salt and sugar to the human body. The idea is that they are absorbed into the blood stream quickly. Do you remember the biology lesson in Osmosis?

It is a good idea to try them out during training so you know what your stomach can tolerate. I have found some a bit too sweet, and to get the right concentration for me to tolerate the taste I water it down to 75% sports drink and 25% water. This works for me, again try out different things in training.

My next blog will be on how to fuel during the marathon.

You can follow Barbara on twitter @50percentdiet or email her at babs@barbarashiells.com about any training issues you might have for the Yorkshire Marathon.

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