Top British rower Katherine Grainger has been unusually idle at this week's world championships. The 35-year-old, who is teaming up with Anna Watkins in the double sculls at Karapiro, is Britain's most successful female rower.

She and Watkins underlined their class earlier in the week, easily winning their heat to advance to Sunday's final, earning themselves the best part of a week to rest up.

It is a marked difference from the demanding schedule Grainger and Watkins experienced in the 2010 World Cup series, when they doubled up in the women's quad with Beth Rodford and Annabel Vernon for all three events.

In Bled, Grainger took gold in both races, in Munich she won gold in the double and silver in the quad and in Lucerne again won gold in both boats.

Bearing in mind that Grainger and Watkins had little more than an hour to recover in between races each time, it was a phenomenal achievement for the experienced duo.

Having decided to focus their energies solely on the double at the world championships, Grainger said they were finding the inactivity rather strange.

"It's really odd having days and days between races and having so much time on our hands," she said. "But we wanted to see what we could do in the double when it was our sole focus and so far it's going well."

Grainger's rowing CV is as impressive as it is varied.

She has won gold at four world championships, winning the women's pair in Milan in 2003, before claiming three consecutive world titles in the quadruple sculls from 2005-2007.

After winning silver with the quad at the Beijing Olympics, Grainger last year competed in the single sculls, taking silver in Poland.

Her versatility has contributed to her success, with Grainger moving confidently from a sculling silver at the Sydney Olympics to a sweep silver in Athens, before returning to the double-oared discipline.

Having represented Great Britain for nearly 15 years, Grainger said she had enjoyed the chopping and changing. "I like having the variety, I like having a change of boats through the years. I've been around a while now and it's been nice to have that variety." However this is the first year she has competed in the double, and also, oddly, the first time she has been in a crew with Watkins.

Given the British crew's dominance of the event this year, Grainger is keen to continue in the double in the coming seasons as they gear up for the London Olympics.

"Obviously it's going very well so far, so I think if we finish off the season as well as we hope then I would say we'll try it again."

At 35, Grainger is by no means past it - top women's single sculler Ekaterina Karsten of Belarus is 38 and shows no sign of slowing down. But having achieved a phenomenal amount in rowing already, it has to be asked, what drives Grainger to keep going in one of the most demanding sports there is?

The London Games in 2012 are an obvious pull for Grainger, particularly when the one obvious gap in her CV is Olympic gold.

Grainger, who was made a Member of the Order of the British Empire in 2006, has had to settle for silver at the past three Olympics and admits she'd dearly love to add gold to her collection.

"It's the one obvious thing I don't have and it's something everyone wants," she said.

"But it doesn't hang over me, I don't feel it's this heavy weight around my neck that I have to go out and get it at all costs and if I don't, it'll be the end of the world. I think of it in a positive sense - it's an exciting thing that I haven't already achieved that of course gets me out of bed in the morning."