In 1853 an American inventor called Elisha Otis unveiled the safety elevator, which is why when normal people want to reach the top of skyscrapers they take the lift.

On March 19, up to 700 men and women will head to the top of the former NatWest Tower, but they won't be taking the lift. They will be running up the stairs, all 920 of them.

It is called Vertical Rush, and it is being billed as the first major stair race in Britain. In the United States a select group of sporting masochists run up the Empire State Building. It is also “popular” in Germany, if that's not an overly loose sense of the word.

Personally, I have never seen any particular shame in using Mr Otis's invention. However, as it's a first, and for charity (Shelter), it seemed a shame to pass up the opportunity to check out the view from the tallest building —183m (600ft) — in the City of London.

Which is why I found myself in shorts, T-shirt and trainers preparing to run up Tower 42. I am not particularly fit, I had not done any training and, while not wishing to be too precise about my age, let us just say that I have more years under my belt than Tower 42 has storeys. Fortunately I had with me two personal trainers, a security official, a Times photographer, the tower's general manager and a first-aid person.

The legal disclaimer on the website stairclimbingsport.com warns: “Stair climbing is a gruelling, strenuous sport and should not be embarked on without first consulting your physician. If such a strenuous activity as this is started without being ready or fit, physically and/or emotionally, serious consequences could result, including death.” A nice touch that, the death bit. Just the thing to set you up for a run up the stairs.

“Anytime you like,” said Peter Merrett, the general manager, stopwatch in hand. I set off at a moderate jog, taking two steps at a time on the grounds that I would only have to climb 460 steps, which did not sound too bad. After a couple of storeys I realised that tackling the tower at double-time might be all right for the super-fit but was not such a good idea for wheezing middle-aged journalists. One step at a time, then.

Two storeys later I began to get a stitch. “Breathe deeply,” said my fitness trainer, Alica, who was going up with me, probably to make sure I did not die on the premises.

I breathed deeply, and moderated my pace to one that was both sustainable and aerobically efficient, as well as ergonomically designed to minimise damage to the musculoskeletal system. I believe it is technically known as walking. Even walking was hard, though. By the ninth floor I was out of breath, and wondering whether my legs would make it. By the 16th there was a steam hammer in my chest, and my lungs felt as if someone was scouring them out with wire wool.

I kept going, though. The pounding in my chest had developed into something seriously industrial and my legs felt weak. Muscular co-ordination started to go and I hung on to the banister like some hopeless old drunk.

“Are you all right?” asked Alica. As I had completely lost the power of speech I panted a little louder, hoping that she would realise that I was still alive — just.

Round and round I went, up and up, not really aware of where I was until I saw above the doorways the most beautiful numbers in the world: 40, 41, 42. Someone gave me water. Someone else, probably Mr Merrett, said my time was 9min 48.3sec. As a superfit participant's personal best was 6min 28sec, I did not feel that was too bad, for a committed member of the sedentary classes.

Talking of sedentary, as I staggered into the top floor viewing area — marvellous views, apparently: I have absolutely no idea. I saw a chair, a lovely, lovely chair and collapsed into it.

“Would you do that again?” asked one of the fitness girls. Don't be stupid, I thought to myself. It's the lift for me from now on.

On the other hand, if I could get my time below nine minutes...

See www.shelter.org.uk/verticalrush

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