Red Bull Defiance is one of the world's most gruelling multisport events, so racing the new four-person option in 2019 is ideal for athletes who have just leapt into the world of fatherhood.
Former All Blacks skipper Richie McCaw has joined forces with Bob McLaughlan, Rob Nichol and Sarah Fairmaid as part of Team Best Foot Forward NZ.
McCaw, with McLachlan, impressively raced to the men's sport category win last year in the two-time World Cup winner's first multisport event.
They went on to finish sixth in the 2018 Godzone Adventure Race in Fiordland, alongside teammates Nichol and Fairmaid.
As a new dad to baby Charlotte, McCaw's experience of adventure racing sleep deprivation has recently come in handy.
"The broken sleep sort of changed things," McCaw says. "Normally, when you are training hard, you want to get a good sleep.
"You get woken up a few times, which is something different to deal with," he says, of life with a five-week-old. "It’s all cool, it’s all worth it."
McLachlan and Fairmaid's kids are old enough to not keep them awake at night, but after years of international adventure racing, they are ready to spend more time at home with their families.
"Originally, Bob and I were planning on having a quiet summer, maybe even retiring," Fairmaid laughs.
"X4 was a good excuse to get rid of the Christmas dinner, and get off the couch and just enjoy it really with our friends."
For Nichol, this was also the motivation to get the awesome foursome back together again.
"With the X4, you get to race with your friends and mix up the combinations, which makes it all a bit more dynamic.
"It will be hard and fast as a result, so I'm keen to see how we go in that space versus the more consistent and solid pace required in an adventure race," he says.
After racing together several times, they know each other well and can rely on the fact that they are all tough nuts to crack.
"The biggest thing that we have is mental strength," McLachlan says. "No-one will quit.
"We could be crawling through the finish-line and we will still be crawling."