Only now has Pearson revealed the extent of the pain she suffered in the lead up to winning gold, admitting the closeness of her win – by just .02 seconds – was only due to the “agony” of the back pain.

She needed extensive massage and treatment between running sessions and in the warm-up to competing in London to manage the pain.

Pearson said that despite the pain in her back she never doubted she would win the race as she was a far tougher competitor than her rivals, the only issue was how great the winning margin would be.

“She only got that close to me because I couldn't run freely, my back was killing me,” Pearson said.

She had eight weeks off training after London but felt this in some way exacerbated her problems because her back stiffened and tightened up.

Pearson said the disc in her back was degenerating and that to ensure she was capable of defending her Olympic gold in Rio the 26-year-old would need to carefully manage her hurdling load in the coming years.

The strain on her back from hurdling has meant that the 100m Olympic gold medallist and world champion will be unable to hurdle in Australia this summer but will hope to compete in the flat sprint at the National Titles in Sydney in April.

"Doing too much [hurdling], being in that position, those angles all the time, was hard on my body going through to the European season and competing at the Olympics as well,” Pearson said.

"If I want to be the world champion again, if I want to be the Olympic champion again, it's a matter of trying to get over it the best way I can, doing all the preparations right without putting my back under too much strain.

"I know I'm not an old athlete, I'm only 26, but just the way my body is ageing at the moment and my disc is degenerating it's just a matter of trying to keep it intact so I can compete at least until Rio."

Pearson said the pain in her back in London was the only reason her rivals got as close as they did.

"It felt at its worst when I was running the heats of London,” she said. "I had a lot of treatment in between reps, when I was warming up before I went out and raced. It wasn't good at all.

"I didn't want to let everyone know because I knew I was in really good shape and I knew all I had to do was get on the track and run and I knew I'd be fine. When I actually raced it wasn't sore, it was just the moments beforehand and afterwards because obviously when you're racing your mind is elsewhere.

"It's just a matter of telling your body that you have to do it, no matter what."

Pearson believed she was in form to break the world record and run a 12.1-second race in London but the pain she suffered before the race and after inhibited her breaking that record. Pearson ran 12.35s to win gold from American Dawn Harper, who was second by .02 seconds.

“It definitely didn't scare me that she was that close to me because I knew they were going to be that close to me, they weren't going to let me beat them like I did at the world championships in Daegu, so it was a matter of keeping my cool about it and doing all the right things,” she said.

“I knew 100 per cent that I was going to win that race, it was just how far ahead I was going to be.

“I still have the confidence for next year for the world championships that I will still be far ahead. I am just miles ahead of the girls in how I race and how much of a competitor I am compared to those girls, and at the same time you have to be the best athlete on the day. But I still think it will be me because I still have that knowledge that even if I am not running at 100 per cent fitness and health that I can still beat them.”