Step-by-step guide to help you avoid the dreaded "wall"

After four months of hauling yourself round the streets, piling up the miles and becoming obsessed about pasta-eating, trainer-choosing and calf-stretching, the big moment is nearly upon you.

The race represents the culmination of possibly the most intensive and prolonged period of training you've ever undertaken in your sporting career - and it would be disastrous to blow the lot now.

The final week's preparation is probably the most important of all. Get this bit wrong and the rest will have been a waste of time.

Mileage

If you're not ready by now, it's far too late.

There's no point at all in desperately trying to cram in as many miles as possible - it'll only make things harder on the big day.

By now your long runs should be well behind you, with your last two hour-plus effort a good couple of weeks in the past.

Instead, take it easy and save your strength for the race itself.

On the Tuesday and Thursday, do a three or four-miler at an easy pace.

Rest up and stretch on the other days.

Equipment

Tempting though it may be to buy a brand new pair of shiny trainers and the flashy vest and shorts that Antonio Pinto will be wearing, you'll be guaranteeing yourself a painful day if you do.

Running 26 miles in shoes or clothing that hasn't been broken in is an excellent way of ensuring that you'll be bleeding from blisters all over your body by the time you reach the Mall.

Stick with the gear that has seen you through training in comfort and don't waste any time worrying that you might not look your best.

After running for four or so hours, a hand-tailored outfit from Julien Macdonald wouldn't be enough to make you attractive.

Diet

By now you'll be used to eating meals that comprise about 70% carbohydrate - pastas, potato, bread and rice.

Some experts believe that notching that up to nearly 100% in the two days before a marathon - a practice known as carbo-loading - will increase your chances of getting through the race without hitting the Wall (the point at which your body has exhausted all available supplies of energy).

Others disagree. Either way you should be eating plenty of starchy foods, keeping the fat content low and drinking lots of non-diuretic fluids (ie water and fruit juice rather than tea or coffee).

On the morning of the race have a couple of slices of toast, a bowl of cereal and a cup of coffee.

If you can carry one without a problem, a high-energy powerbar in the mid-to late stages of the race won't do you any harm, either.

Rest

Take it easy.

Your body is about to undergo the biggest test you've ever put it through.

Get lots of sleep, don't decide to re-lay the patio and don't go out on the town for a night of hard-core booze action.

The night before, go to the cinema, curl up with a video at home or finish off that interminable Jeffrey Archer book you've had knocking around since your summer holiday.

If you can, book a massage with your physio.

As for other ways of ensuring a relaxed night's sleep, well, that's up to you and your partner.