KNOWING what to pack for a long-flight can often be a difficult decision to make.
Along with jumpers and travel pillows, experts have bizarrely explained why a tennis ball should be included too.
Long flights can increase the risk of blood clots, due to the lack of circulation in the legs when sitting for long periods of time.
And a tennis ball could alleviate this.
Professor Ali Ghoz, an orthopaedic surgeon, previously told The Daily Star: "By taking a tennis ball or a massager on the plane this will help increase circulation."
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This is because the ball can be used to roll out any tight or sore muscles, particularly in the legs and back.
Other experts have backed up using tennis balls to alleviate pain.
llinois-based physical therapist Peter Allan Schmitt told USA today: “[Tennis balls are] the perfect size for most areas and they have a little bit of give, which I like.
A fitness trainer even said that two tennis balls was the ideal.
Laura Coleman said on her social media: "Take two tennis balls, put them in a sock. Take that sock, put it in the middle of your back.
"It doesn't matter where, just put it anywhere from the bottom of the shoulder blades to the top of the hips and dig in."
"It helps break loose the middle of your back which gets super tight if you're stuck sitting, especially on a long trip and especially on an airplane."
The LTA even released an entire "tennis ball physio" guide when using one for fitness.
They state: "Trigger point release exercises are a wonderful way to help release tight, knotted up muscles.
"Alleviate the pressure of tight calf muscles with this simple ‘gastroc’ exercise with your tennis ball.
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"Place the ball on a point on the calf.
"Bend the opposite leg and allow some weight to move on to the ball and roll it up and down the calf."
A tennis ball won't break the bank either.
The cheapest we've found is a pack of four from Home Bargains for £2.99, working out to 75p per ball.
Using a tennis ball isn't the only way to keep your circulation moving during a long flight.
Experts advise always wearing compression socks on flights to reduce swelling.
And the A-B-C alphabet trick is often used by flight attendants.
Emirates flight attendant Lauren Guilfoyle told Reader's Digest: "Motion each letter of the alphabet with your foot to get the blood flowing and avoid ankle swelling."
