Gym rats are in a pickle.

Pickle juice — the salty, tangy liquid used to turn cucumbers into pickles — has become the new drink of choice for fitness fanatics.

“There’s an increase in demand [from fitness people] for just the brine,” Mike Chu, manager at the Pickle Guys, tells The Post. At the Lower East Side shop for sour delicacies, people in the know can special-order off-the-menu brine straight from the pickle barrel. Prices range from $3 to $15 for containers of the salty elixir — and up to $45 for a bucketful. Devotees say it’s worth the cost.

“I believe it really helps with recovery and hydration,” professional boxer Jason Markland, 35, tells The Post. The MMA fighter, who’s teaching a high-intensity interval training class at the new boutique studio chain Fithouse, says that he drinks pickle brine after hard days of training. “You don’t feel an instant change, but you know it’s working. If you get cramps during training and you drink it, you can feel the difference.”

Leigh Gerson, a trainer at Soho Strength Lab, agrees. The 35-year-old runner, who has won several half marathons, feels fortunate to live just a few blocks away from the Pickle Guys.

“Pickle juice is really hydrating after a long run,” Gerson says. “I drink it straight from the jar. You can fill it back up with water and let it sit with the pickles for a bit and get even more juice.”

Dr. Theodore Strange, a Staten Island-based internist who has run 25 marathons, says that pickle brine can help to replace fluids and electrolytes after strenuous activities.

“Pickle juice is high in sodium and potassium, which helps to normalize the imbalances that occur — like cramping when muscles are being overused or dehydrated,” he says.

Still, that doesn’t mean everyone should start chugging this “natural form of Gatorade,” Strange says. “If you have heart disease, it would not be recommended to drink pickle juice or anything like it that is high in sodium.”

‘If you get cramps during training and you drink it, you can feel the difference.’
But if you are a reasonably healthy individual who has a steady workout routine, Strange says he doesn’t see anything wrong with adding pickle brine to your post-workout hydration arsenal.

“It’s become one of those fads,” Strange says. “But I don’t see a problem with it, as long as it isn’t overused.”

The same goes for a pre-packaged “pickle juice” shot by the Pickle Juice company, which has been on the market since 2001. The briny drink was formulated to help stop cramping during and after a strenuous workout. The only catch? The cramp-targeting substance doesn’t technically contain any pickle juice — just a mixture of water, vinegar, salt and various vitamins. Its lack of legitimate pickle content doesn’t seem to trouble customers, as the company’s sales have doubled every year since 2015.

Still, pickle purists like Gerson would rather stick to the real juice.

“It’s just delicious,” she says. “Plus, with the real juice, the bonus is pickle brine makes for a great post-workout dirty martini.”