When American tennis player Frances Tiafoe said pickle juice had helped him reach the quarter-finals of the Australian Open, plenty of people were a little taken aback/grossed out.

After all, who swigs the remnants of a jar of pickles to boost their sporting performance?

More people than you might think, actually.

Taking the Australian Open in isolation, two of the sport’s rising stars – Tiafoe, 21, and Russia’s Daniil Medvedev, 22 – have been spotted drinking it in Melbourne this week.

And widening the sample size a little, a photographer snapped Arsenal’s 22-year-old Uruguay midfielder Lucas Torreira drinking from a bottle labelled “pickle juice” in the Gunners’ 2-0 victory over Chelsea last weekend (although he did swiftly spit it out!).

Is this sport’s latest fad? And what is the science behind it all? BBC Sport finds out.

Tiafoe’s not-so-secret weapon

Unseeded Tiafoe was a surprise quarter-finalist in the Australian Open, and made further headlines with his choice of replenishment following that win over Bulgaria’s Grigor Dimitrov in the last 16.

Speaking about the gruelling four-set match, which lasted three hours and 39 minutes in the Melbourne heat, Tiafoe said: “I had the break, but started to feel my body.

“He played a good game to break me. After that, as you asked me, I was trying to stay alive. I was downing pickle juice, having that like Kool-Aid, just trying to get that done.

“I’m talking straight up: just downing it. It tasted terrible. I’m feeling terrible right now, man.”

The following day, Medvedev took time out from his match against Novak Djokovic to down some of the pungent fluid.

John Millman, the 2018 US Open quarter-finalist, was commentating on that match for television and was asked about the pickle juice.

“It helps the cramps,” said Millman. “There’s a lot of salt in it.”

When asked how it tasted, the Australian replied: “Terrible.”

It tastes bad… but does it actually work?

In a word: Yes.

Dr Mayur Ranchordas – a senior lecturer in sport nutrition and exercise metabolism at Sheffield Hallam University – has used the technique with professional cyclists and Premier League footballers.

And while, he says, the results are compelling, it is not necessarily for the reasons you might initially expect.

“Pickle juice contains sodium, potassium and vinegar and the obvious conclusion would be that it replaces sodium and salts lost when playing sport in a hot and humid environment like the Australian Open thus prevent cramping,” said Dr Ranchordas.

“However, how it really works is that it triggers a reflex in the mouth which sends a signal to stop muscles from cramping. That’s why it is drank at the onset of cramp.

“It stops cramping 40% faster than drinking water.”

Dr Ranchordas says it is particularly effective as a treatment for cramps in warmer conditions or when sporting occasions last longer than anticipated – be it a five-set tennis match or in extra time of a football game.

Just last month, India batsman Cheteshwar Pujara was shown grimacing on TV as he took the foul-tasting fluid on board during a marathon innings in oppressive heat in Adelaide.

What else is it good for?

The internet is full of stories of how pickle juice can cure alcohol-induced hangovers. One website even suggests pickle brine is the definitive hangover cure in some eastern European countries.

Throw in the fact it contains antioxidants, is said to help control blood sugar levels and boost gut health and you’re on to a winner next time you reach for a nice refreshing glass of the stuff.

And the craziest thing of all?

It is actually good for your breath, because it kills bacteria which breed in your mouth and create a stink.

Now you’re convinced, right?