Expert explains why everyone should put a tennis ball in their carry-on

When you decide to travel, it can be tough to figure out what to pack in your precious hand luggage.

There's only a finite allowance of space and weight so you've got to prioritise or face paying some extra fines - just make sure you leave enough room for the tennis ball.

'Hang on, a tennis ball?' I hear you ask, dear reader, but bear with us because an expert has explained why you should pack one.

Registered osteopath and sleep therapist Tracy Hannigan, working with InsureandGo, told Metro that wrapping a tennis ball in a hand towel made for a handy body massager.

She said you should 'put the ball in the middle of it and roll it like a sausage' then apply pressure using the ball to relieve pressure on your joints.

A tennis ball in your hand luggage is apparently the travel hack you need (Getty Stock Image)

"A tennis ball is small and light and can help you to apply soothing pressure to points you might otherwise not be able to reach," she said.

This is one of those lesser known travel hacks but rolling it over your shoulders, legs and back can make sitting in your plane seat somewhat less of a still and arduous experience.

It helps get the blood flowing in a situation where you'll be sitting in a cramped place for an extended period of time, and the expert said you could use it for various exercises in your seat.

"You can even stretch your lower back in your plane seat, by crossing your legs and leaning forward, as if you’re trying to reach down to the crossed-over foot with your elbow," she suggested.

However, we might not recommend doing this on a budget airline since there'll be precious little room to cross your legs or lean anywhere.

Oh yes, that'll be great for my back (Getty Stock Image)

Getting up and stretching your legs every two to three hours of your flight is encouraged to keep you active, but there are some people who take staying active while on the move a little bit too seriously.

A few folks will even attempt to get in a decent workout while the plane is mid-air, though you might want to be aware of the state of some of those cabins before you try that.

Flight attendants will tell you all day long not to take your shoes off and presumably if you start doing yoga or push-ups in the aisle you'll be coating your skin with all sorts of unhygienic substances.

Maybe it's best to stick to tennis balls.