Four years ago a fresh-faced 15-year-old unknown athlete slipped into Beijing unnoticed but returned from the Paralympics as one of the darlings of New Zealand sport with three golds and a silver.

Things are much different for Sophie Pascoe at London 2012 - this time the Christchurch swimmer has a target on her back and she's been doing everything possible to make sure nobody can hit it.

Now 19, she has matured both mentally and physically, the latter partly as a result of a gruelling training regime under coach Rolly Crichton, who has pushed the below-the-knee amputee to the limits in the quest to maintain her dominance.

His regime has included increasing her distance in the water, implementing a stringent dry land programme and undertaking altitude training - the pair have spent the past five weeks at Flagstaff, Arizona, in temperatures touching on 40 degrees Celsius.

"We've done a lot of different things," Crichton said.

"She came away from Beijing very well known. She was young and she took everyone's hearts but we're four years on now and she's a very mature and professional 19-year-old who is very determined and works very hard.

"Through what she did in Beijing, though, she is the target here. That's why we've had to cover the bases and go to major meets around the world. We've had a couple of wake-up calls, but then Sophie's gone out there and put the pressure back on those athletes."

The last four years haven't always been easy - she lost her training facilities in the Christchurch earthquake - but Pascoe has adopted Crichton's hard-nosed attitude.

"You don't find out who you are and what you are until something like that [the earthquake] happens," Crichton said.

"Travelling and going to different parts of New Zealand is hard. It's been different and we've learnt to adjust very quickly so when you come to places like the Olympics it's not that hard for us.”

Pascoe, who lost her left leg below the knee after a lawnmower accident when she was 2, will compete in six events in London; 50m and 100m freestyle, 100m butterfly, 100m backstroke, 100m breaststroke and the 200m individual medley.

She is the defending champion in the latter three events and won silver in the 100m butterfly in Beijing.

"The challenge is to do personal bests," Crichton said.

- © Fairfax NZ News