So how fast can she run?

Chrissie Wellington says she’d like to run a 2:20 something at the London Marathon.

It begs the question just how much faster can one run a standalone marathon in comparison with the one everyone runs to finish an Iron-distance event.

Wellington has consistently posted some of the fastest ever Iron-distance run times for women.

In Roth last July, Chrissie Wellington posted a 2:44:35 marathon split. The previous year she ran 2:48:54. In 2009, she ran 2:57:32.

At Ironman South Africa in April 2011, she posted a 2:52:54 and at Ironman Arizona in November 2010, Wellington ran 2:52:56.

Wellington also has run fast in Kona: 2:52:41 in 2011, 3:03:05 in 2009, 2:57:44 in 2008 and 2:59:57 in 2007. *Mirinda Carfrae holds the run course record on the Big Island with her 2:52:09 last year.

There are two women who offer potential parallels for Wellington, though every athlete is different.

First, there is Desiree Ficker who finished second at Kona in 2006 when she ran 3:11:49. She has a marathon PB of 2:40:28.

Second, there is Joanna Zeiger, the 2008 70.3 World Champion. When she won Ironman Brazil in 2005, she ran 3:16:08. She has a marathon PB of 2:43:48.