Lizzy Yarnold: 'The bob skeleton is petrifying and unnatural but I love it'

She did not choose bob skeleton, it was chosen for her, yet the brave Brit has medal chances at this week's World Championships

It was four years ago that Lizzy Yarnold opened a letter at home in Kent and read that she had a future in bob skeleton. Yarnold was disappointed, she fancied herself more as a modern pentathlete.

This morning, Yarnold will place her sled at the top of the 1,772m of the St Moritz bobrun for the first of four runs at speeds of up to 85mph down the packed ice of the world's most famous, and oldest course, by the end of which – presuming she reaches the bottom unscathed – she could be a world champion come tomorrow lunchtime.

"I love it," says Yarnold. "I've competed there twice. It's home – the British are the founders of our crazy sport and this is where it all started. It's very poetic."

Yarnold has gone, at high speed, from being talent spotted via one of the innovative schemes run by UK Sport to fit athletes into a sport they suit to become one of the best in the world at her new discipline, and one of Britain's leading hopes for a Winter Olympic medal in Sochi next year. This week's World Championships is followed by a first go on the new Sochi run.

It is a rise that had an accidental beginning. Her elder sister was picked up by handball at a previous talent day and Yarnold, a heptathlete and fond of variety, had her eye on an Olympic place in the modern pentathlon. The talent scouts disagreed and a few months later she found herself staring down a bobrun in Lillehammer.

"I thought, 'yeah, I'll give it a go'," recalls Yarnold. "It was petrifying." She laughs at the memory. "Yes, petrifying. You get in at the top of an ice shoot and then you get out at the bottom and you just hope everything goes very well in between. It is not a completely natural thing.

"I thought, 'am I mad to do this again?' But then my reaction was, 'if I can get to this corner a bit better, if I can keep my position straight and pick up more speed, think how quicker I can be'."

Britain is building a tradition of success on the ice. Shelley Rudman won silver in the 2006 Games and Amy Williams gold on the controversial Whistler run four years later. Williams has retired but Rudman too competes today and remains a medal contender, while Yarnold is looking to improve on last year's World Championship bronze and a promising season on the World Cup circuit. Williams and Yarnold remain close. The two had dinner before Yarnold departed for Switzerland (and Williams is Yarnold's landlady in Bath).

It was on the Canadian course where Williams won gold – and where the Georgian Nodar Kumaritashvili was killed on the eve of the 2010 Winter Olympics – that Yarnold suffered her worst moment, blacking out on a training run last year.

"I got to the penultimate corner and was travelling at a good 90mph – faster than a lot of the guys that day. I went into the last corner and there was so much pressure my brain just wasn't prepared, or couldn't take it so I just switched off. I went into safety mode. I got to the bottom and I was struggling, feeling a little unwell – I went to see the doctor and was fine to go for the race."

Two days later she finished third in a World Cup race. "It could have [put you off] but that's one of the things you need to do in skeleton. You have to be very confident in what you do and your ability. So if I go into a race knowing the last run I did on the track was where I blacked out that was a great test for me. I quite enjoyed that challenge."

A typical run lasts around a minute, but St Moritz is longer, the longest on the circuit; 70-plus seconds at 80-85mph, your face millimetres from the ice.

"When you go into a corner with high pressure the snap Gs are tremendous – you can't hold your head up," says Yarnold. "It is forced down on to the ice. You do get quite a sore neck. Every run that I take I am extremely nervous. You have to have those nerves because it could be such a dangerous sport you need to have the adrenalin and the nerves as well. The adrenalin rush happens every single time. At St Moritz there is a long straight between a corner called Gunter Sachs and Martineau where you really feel that you are going to take off and fly. You can feel the air rush by you – it is an amazing feeling."