Video: Richie McCaw and wife Gemma Flynn complete Coast to Coast race

Former All Blacks captain Richie McCaw and wife Gemma Flynn have completed the Coast to Coast mountain run on the Southern Alps of the South Island's West coast.

McCaw completed the 30.5km race in 4h 20m 01s to finish with the 11th best time in the male category, while Flynn was clocked in at 5h 18m 40s to finish fourth overall in the women's race.

The two-time World Cup winner credits his fitness for completing the gruelling race, which he's done his utmost to maintain since his retirement for international rugby.

"I'm probably as fit as I ever was playing, but in a different way," said McCaw.

"I try not to let many days go past without doing something and I find when I don't do something the body starts to creek a wee bit.

"I way prefer this to road running cause it hurts the body running on the road."

Despite completing the mountain run with an impressive time, McCaw only decided on Monday that he was going to take part in the race.

"Monday I decided I'd do it. I knew Gemma and my sister were going to do it and in the back of my mind thought I could have done it."

"We did quite a bit over the summer, a few hill runs so it wasn't like I was completely cold but there were a few points where I wish I had done more."

McCaw paid homage to all the Coast to Coast athletes after the race saying he has 'loads of respect for those guys.'

"These guys are tough. Richard Ussher did that run in 2h 50m, I don’t know how someone does it that fast."

McCaw was hoping to complete the race in less than four hours.

The 148-Test All Black will now take some much needed time out to recover before embarking on his next adventure.

Newshub.