The night of the marathon was the worst of my life. My body hurt all over but my heart was totally broken Paula Radcliffe

Radcliffe pulled out of the marathon with four miles remaining but says the pressure of dealing with a quad injury was responsible for the heartbreak.

"The injury would clear but then return each time I tried to run," she told the Daily Telegraph.

"I was unable to sleep with worry some nights and suffered an upset stomach from the doses of anti-inflammatories."

Radcliffe was favourite for gold in the marathon and expectation from the British public was massive going into the Olympics.

Her preparations for Athens were going well but she was hampered by the injury which was picked just two weeks before the Games.

And the problem was compounded by a mass of clotted blood beneath the muscle.

"My quad felt a little tight during a run in Spain and afterwards went into total spasm," Radcliffe said.

"I was determined to get to the start line and we took a very aggressive line of treatment but the period was very stressful.

I did not for one moment consider retiring or taking time out Paula Radcliffe

"I was very nervous on race day but when I warmed up, I felt that the leg would hold out and I relaxed.

"However, after just 10km my stomach problems started and my legs were also feeling very weak. Eventually I had to concede that there was no way I could push my body any further.

"I was in shock and disbelief that it could end like that and even tried running again but my legs could not carry me."

"I still don't have the answers and may never get them," she added.

"However, it's most likely that I had run my marathon just to get to the start line.

"The anti-inflammatories and stress upset my bowel so that I was unable to absorb enough energy and nutrients.

More agony for Radcliffe

"Had I pushed further I would have damaged my body further. As it is, tests showed my liver was struggling to cope and I lost a lot of weight.

"The night of the marathon was the worst of my life. My body hurt all over but my heart was totally broken."

Despite her marathon agony, Radcliffe decided to compete in the 10,000m five days later but dropped out with eight laps remaining.

"I don't have any regrets about trying the 10,000m," she said.

"At least I won't always be wondering if I could have raced it.

"My legs were just unable to recover from the trauma, even now they are still sore."

Turning the corner

Radcliffe is now recovering from the experience and, with the injury gone, has began running again.

"I am concentrating on rebuilding my body. I feel angry and hurt and am determined to learn from the mistakes I made.

Radcliffe baffled by failure

"It was when I began running a few days ago that I began to turn the corner.

"I don't doubt my ability to become stronger and wiser as a result," she said.

"My dream is postponed, not over, and as soon as I am ready I will set new goals on the way to my next shot at it."