Desert run in a rhino suit

No-one has ever finished this race in costume before - and this will be my first and last time. A seven-day run across the desert is not an event you do more than once.

After running six marathons in costume to raise money for Save the Rhino - three in New York, three in London - this seemed like a natural progression.

But as the race day approaches I'm increasingly thinking, 'Why am I doing this?' It just hadn't crossed my mind until recently just how tough it's going to be.

I keep waking up in a cold sweat, having had nightmares about dropping bottles of water and watching them disappear beneath the sand.

Two steps forward, one sliding back

There's eight of us doing the rhino run. Each group of four will have the costume for an hour, taking it in turns to wear the suit while the other three act as zookeepers.

Suffer in the Sahara
Day One: 16 miles
Day two: 22 miles
Day three: 19 miles
Days four and five: 44 miles
Day six: 26 miles
Day seven: 13 miles

I've heard that by the last day, most people are limping and crawling. Unlike the London marathon, there's very little elation at the finish line - most people seem to just crumple in a heap and cry.

It's ridiculously hot during the day. Last year the highest recorded temp was 61C (141F) - I didn't know it could even get that hot - and most days are between 40C to 45C (104F-113F).

That's exacerbated by the fact that you've got to carry all your own kit, including water and an anti-venom pump.

At night it drops to about zero Centigrade. We might be fighting over the rhino suit for a bit of added insulation then, but we certainly won't be during the day.

The suits we use for marathons were originally built for a theatre company. Inside is a plastic lining which creates a sweat box - someone described it once as running in a giant crisp packet. Very noisy, very hot, very sweaty - not designed for running in any way whatsoever.

We had planned to take one of these to Morocco, but soon realised we'd suffer really badly.

So we went back to the person who built the original costumes - the same person who built the Teletubbies - and she created a new suit for us. It's about a third lighter and instead of a plastic liner it's got gauze panels so the air flows through it.

I ran in Hyde Park in it last week, much to the bemusement of the dog-walkers, and it was a revelation. Normally I'm sweating within 20 seconds but this one felt great.

Click here to see if the rhino team made it

Running marathons in costume is great fun - and a seven-foot rhino running down First Ave in New York or the Embankment in London does tend to turn people's heads.

I put my name on the front so people shout out, 'Rhino Neil!' - like the American actor - and the energy really helps me get through those last few miles.

My personal best is five hours 20 minutes, because I've always been a little bit slack in my training.

For the desert run I have done a bit more to prepare. I cycle to work every day so my baseline fitness is pretty good, and I'm running 25 to 30 miles a week.

Purist runners will probably think that I don't stand a hope in hell but I believe quite strongly that a lot of it is in your head. I'm doing this for an amazing cause - we hope to raise £200,000 - and that probably makes up for 200, 300 miles training.

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