Nutrition and hydration for races - 20 miles to marathon

Nutrition and hydration for races - 20 miles to marathon

For races this long nutritional planning is a must! Sarah Coope gives practical advice and tips on recovering from 'hitting the wall' or 'bonking'

Of all the events you will do, it is probably most important to get your nutrition right for an event over 20 miles.

The week before:

Training needs to be reduced both in intensity and distance. This will allow the body to store more fuel providing you maintain your normal diet. Try to sleep well, relax with a book, film or something that will take your mind off the race. A week of worrying about it will not help one bit.

If planning to carbo-load, increase intake to a premium 65 to 70% of total calories, so someone eating 3000 calories daily should be looking to find approximately 2100 calories (525 grams) of them from carbohydrate sources.


Eat  protein alongside carbohydrate © Pixelbliss
ProteinMaintain an intake of protein with the carbohydrate as this has been shown to increase absorption of glycogen - white and red meat, fish, cereals and pulses are a good source of protein. (Glycogen is the body's store of carbohydrate (and water) - kept in the muscles and liver.) Do not experiment with new foods, or heavily spiced foods before you start.

Fluid intake needs to be at a premium as water is needed for glycogen storage. Avoid alcohol and caffeine drinks as these can have a dehydrating effect on you. You are well hydrated if your urine is clear and you need to go frequently. If the race will be run in hot conditions consider using a fluid replacement drink during the week to ensure that your electrolytes are balanced before you start.

Avoid alcohol and caffeine drinks as these can have a dehydrating effect on you

If you have travelled abroad to an event beware of the water. Drink bottled water, avoid salads, ice-cubes, water melons and fruit that doesn't have to be peeled. Even if locals can drink the water it doesn't mean that you will tolerate it immediately. It would be better to try it out after the race. Find out in advance what will be given out at the aid stations. If possible get a sample to try so it is not new on race day.

Race day

Get up at least two hours before the start of the race. Eat a high carbohydrate snack of approximately 300 calories. You may need more or less depending on your metabolism and you should have checked this out on your long training runs.

Drink at least one water bottle (750 ml). Have a warm drink to stimulate the bowel, but beware of caffeine. This can cause problems if you are already stimulated with nerves and can lead to a racing pulse and dizzy feeling. If this occurs have a carbohydrate snack and try to relax. The caffeine can also have a diuretic effect which is not helpful at this stage.

During the race

energy gelStart drinking water from the first water station. Continue at each one to take a cup and drink a little. If the weather is hot or you are running very hard you will need more. Remember each mouthful is about 25 ml. I suggest taking in 800-1000 ml every hour on a moderate intensity run and inclement weather, so work out how many stations you will go through in an hour and take enough sips per station. If the weather is hot and the pace fast, increase this amount.

Look to take in energy each 30 minutes. If energy drinks are being supplied on the course find out the concentration before-hand. If it is higher than 6 to 8% then take additional water with it to aid absorption.

Avoid taking in too much solid food if you are running very hard because it will be very hard to digest and can cause stomach upsets. If you are racing up to 3.5 hours you could use gels/squeezies for energy - plan to take one every 40 minutes before an aid station and take a cup of water with it.

Stick religiously to a plan of hydrating and fuelling. This is essential to a good race, and you will be wasting all your training if you mess your fluid intake up on race day - guaranteed to make you miserable.

If the run will take you over 3.5 hours and you are running more aerobically then you may be able to tolerate some solid food. Eat once an hour, alternating with a sports drink. You should be looking to consume 200 to 300 calories an hour.

If you hit the infamous 'wall' or 'bonk' during the race, which often happens with races around marathon distance, it generally means you have run out of glycogen

If you hit the infamous 'wall' or 'bonk' during the race, which often happens with races around marathon distance, it generally means you have run out of glycogen. There are many reasons for this including insufficient carbo-loading the week beforehand, and the classic - going out too hard.

Glycogen is like petrol, you only have a certain amount and you need to conserve it. When you are running hard, the primary source of fuel will be glycogen. When you slow down, it will be fats.

Your body always uses a mixture of the two and the key to marathon running is to get the balance right - fast enough to get a good time but not so fast that you run out of glycogen forcing you to slow down.

If you do hit the wall or bonk, it is possible to come back from it:
  • Slow right down and eat anything on offer at the aid stations.
  • Continue moving slowly to allow time for the food to be absorbed.
  • If you have gels or squeezies then use those.
  • The key is to keep going slowly until you feel the energy boost from the food. Sometimes this can take up to half an hour, however do not then repeat your mistake by going too hard.
  • Start a little more conservatively and gradually increase the pace. Keeping it aerobic (i.e. so you could talk if you wanted to) will help, as you will be burning fats predominantly.

Advice I found useful before my first marathon was to run the first 1/3 feeling I could go faster, the middle 1/3 feeling just right - a nice steady pace - and the last 1/3 feeling hard, like you are pushing the pace. This will usually give you even splits because the perceived effort gets harder as you get more tired though your pace remains the same.

After the race
Race day ©Goran Bogicevic
race dayRe-hydrate. This is a priority and you should immediately start taking in water and a sports drink. I would choose one specifically for post event that also contains carbohydrates. If you are feeling light headed, dizzy, disorientated and/or overheated you are dehydrated and probably glycogen depleted. You will start to feel better once you can ingest some energy, preferably in the form of carbohydrate with a bit of protein. Consider something salty such as a bag of crisps, sports drink or sprinkle a little salt onto a sandwich such as tuna, cheese, peanut butter etc.

Avoid alcohol until much later after the race so that your body can recover correctly. A long distance race such as marathon is exhausting both physically and mentally and you need to thank your body by giving it what it wants - glycogen (from carbohydrate) and water. Continue to snack throughout the few hours after the race eating about 50g (200 calories) of carbohydrate a time.

It can take up to a week or more before you feel right - during this time no heavy training should be undertaken. Everything needs to recover, so a high carbohydrate intake and maintaining good protein levels is a must during recovery.

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