'The meaner we are, the better we get along' say Race Across the World siblings

When Katie's older brother Harrison told her he'd entered them into Race Across the World she wasn't filled with enthusiasm.

The BBC show challenges pairs of travellers to tackle an intrepid expedition with no phone and limited cash.

Five teams compete for a £20,000 cash prize by attempting to be the first to navigate more than 12,000km (7,450 miles) across Europe and Asia.

"I was just super-nervous and I hadn't really watched it before," recalls 21-year-old Katie.

"I was in denial that I was going on the show until the start line, to be honest.

"Harrison was the real driving force."

Being dropped into an unfamiliar country with a daily budget of less than £26 each, which can only be topped up by taking on odd jobs, makes for great entertainment if you're watching at home.

But duos in previous series have been pushed to their physical and emotional limits as they missed connections or ended up losing hours after following bad directions.

However, it is a chance to bond and see new places - something siblings from Manchester Katie and Harrison, wanted to do, in contrast to the stereotype of bickering brothers and sisters.

Account manager Katie tells BBC Newsbeat spending every day with her brother was actually the easiest part.

"We just know each other so well and we're just like an extension of each other," she says.

And she thinks their bickering can actually be a help.

"The meaner we are to each other, the better we get along.

"Other siblings may use that as a fight but the meaner we are, the stronger our relationship is."

Harrison says one of his biggest challenges was persuading his sister to take part in the first place.

"I know she's always wanted to go travelling and this was like the perfect opportunity for her to go and do it," says the 24-year-old finance assistant.

"I knew she'd love the travelling aspect, but it was a lot of forcing her to fill out application forms and come and do interviews with me.

"I think as the process went on, she got a lot more confident in herself."

Harrison says sibling spats were the least of the pair's worries as they took on the voyage.

Previous seasons have required contestants to resort to old-fashioned methods to get around, including hitchhiking and relying on the kindness of strangers.

Harrison describes the experience as exhausting.

"You're never local to anywhere. You never have any idea," he says.

"If you want to find out where the toilet or shop is, you've got to go and ask someone and that is socially exhausting and draining.

"You can't account for this or the mental situation that the race puts you in that whole time."

Harrison says the average age of the contestants, one of the youngest ever seen on the programme, was a positive.

"We are quite young, but then when you see all the others on the start line and you realise how young they are, it makes you feel a little bit more at ease," he says.

But if Harrison's strategy was scoping out the competition on the start line, Katie's was a lot more practical.

Don't lose the money, the map or the passports.

"This was my only tactic," she says.

Listen to Newsbeat live at 12:45 and 17:45 weekdays - or listen back here.