Wednesday 9 January 2013

Marathon des Sables: how to prepare for heat


52 degrees. That's how high the temperature got last year in the Sahara. To be honest, I couldn't tell the difference between 42 and 52 degrees. It was just bloody hot.

The heat affects people in different ways. It doesn't affect some runners at all, particularly those who are already used to running in hot weather (alas not us Brits!). Others get severe heat exhaustion and end up being pulled out of the race.

I found I just felt vaguely nauseous most of the time. The heat slowed my pace down to a mere snail shuffle at the best of times too. My hands and feet became swollen and my heart hammered in my chest.

The problem with heat
Some runners are concerned with heat in the Marathon des Sables for health reasons, others for performance reasons.

Health wise the main problem with running in the heat is it makes you sweat more than normal to cool you down, and when you sweat you lose vital electrolytes and fluids. If these are not replaced effectively, you will end up dehydrated and in a mess, with muscle cramps, hallucinations, talking rubbish and in worst case scenario, being pulled from the race. This is also known as heat exhaustion.

Heat oedema is also an issue. Blood vessels have to dilate to send fluid to extremities to get rid of the heat in the body. However the heart has trouble getting it back to the centre because of gravity, meaning your fingers and toes swell up. Not usually a problem, except when you are trying to prevent the dreaded blisters!

Performance wise, you run slower in the heat. Why? Your blood volume decreases due to sweating, meaning there is less oxygenated blood to go round the body, meaning less oxygen gets to your muscles - where it's needed. There is also the double whammy of your blood being diverted to the skin to cool down, rather than your muscles, where it would normally flow to in colder climes.

How best to prepare for the heat - before
Sort out a routine for drinking and taking salt tablets. I worked on a basis of 150ml every 15-20 minutes and a salt tablet every 30-40 minutes.
Trial electrolytes before you go and choose ones that you can cope with. I choose neutral ones eventually as sweeter ones just made me feel sick.
Take more electrolytes about 3 days prior to starting.
Be aware you will run MDS slower than in Britain, and remember this when you are out there. Don't let it become a negative thought as there is nothing you can do!
About three weeks before you fly out, start a heat acclimatisation programme. The two best ways to do this in the UK is 1) exercise in a sauna 2) run in lots of clothes.
There is also bikram yoga, but I found this too humid to represent conditions, and I developed blisters from it too. Don't forget two main rules - build up time spend exercising slowly (15 minutes to begin with) and take plenty of water and electrolytes in.

What to do when you are out there
Wear a white hat with neckguard.
Wear shoes that are a size too big to allow your feet to expand.
USE your routine that you have prepared for drinking water and taking salt tablets, but do adapt it if you need to. Having a routine is good a it forces you to remind yourself regularly to drink. It doesn't take long to become dehydrated, and therefore disorientated and confused about what you should be doing when.
Smother yourself in P20 - you don't want to deal with burn skin. P20 is excellent. You only need to apply it once.

Good luck!

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