When it's so godforsakenly hot outside that you contemplate working out next-to-naked or skipping your workout altogether, breathable workout gear isn't merely a luxury—it's practically essential. (Unless you wanna go buck naked.)

Now there's a new option for running free—one that doesn't include terrifying your neighbors.

A group of researchers at MIT have developed a "breathing" workout suit made for those blistering, humid workout days when you might as well be running through the Amazon, according to a press release published in Science Advances. Yes: The suit literally breathes. So even if you sweat buckets on the reg (and there are ways to stop excessive sweating), this apparel can keep you cool—and far better than your typical cotton tee.

How it's made and how it works

We'll be honest: The garment looks a little alien, or at least like a next-level version of Spider-Man's usual street clothes—but its tech is far more novel than your friendly, neighborhood web-slinger ever put on.

The MIT project is called bioLogic, and it's inspired by living organisms like pine cones and bacteria, which can change its structure as humidity changes. The shirt has sweat- and humidity-sensitive cells, so when you start sweating, the shirt opens flaps along your body's main hot spots.

To make this particular natural shape-shifting garment, researchers worked with a strain of E. coli that's incapable of causing disease but capable of shrinking and swelling depending on how much moisture's in the air. After harvesting the cells in a lab, scientists used a cell-printing method to "print" two-layer structures of E. coli onto sheets of natural, untreated latex. They then placed the fabric on a hot plate, after which the cells shrunk, curling the latex layer up. When exposed to steam the cells expanded, flattening the latex. Even after 100 cycles, the cells stayed stable, never degrading in performance. Finally, the researchers worked the biofabric into a wearable garment—a living second skin. The running suit you see is lined with these live cell-lined latex flaps along the back.

These flaps aren't just punctured into the fabric at random; the positioning and size (from the length and width of a thumbnail to a finger) is based on your body's heat and sweat maps.

"People may think heat and sweat are the same, but, in fact, some areas like the lower spine produce lots of sweat but not much heat," says study co-author Lining Yao. "We redesigned the garment using a fusion of heat and sweat maps to, for example, make flaps bigger where the body generates more heat."

And while the notion of living, bacteria-powered workout suits may freak you out, the researchers say these cells are safe to touch and even eat (though we don't suggest you start gnawing on your sleeve). What's more, microbial cells like these can be cultivated in huge amounts and adapted to express many different functionalities aside from sweat management.

"We can combine our cells with genetic tools to introduce other functionalities into these living cells," says lead study author Wen Wang, a former research scientist in MIT's Media Lab and Department of Chemical Engineering. "We use fluorescence as an example, and this can let people know you are running in the dark. In the future we can combine odor-releasing functionalities through genetic engineering. So maybe after going to the gym, the shirt can release a nice-smelling odor."

Come to think of it, that's not a bad idea.

How it performs

In trials, participants wore the suit and worked out on treadmills and indoor bikes while researchers monitored their temperature and humidity with small sensors across their backs. After about five minutes of exercise, the suit's flaps started peeling back, just as participants reported feeling heated and sweaty. The flaps removed sweat from the body and lowered skin temperature better than similar running suits, according to sensor readings.

As for what the suit feels like? "It felt like I was wearing an air conditioner on my back," Wang said while testing the suit on an indoor bike. 

The researchers have also fashioned a running shoe with an inner layer of similar cell-lined flaps to air out and wick away moisture.  

The future of biohybrid wearables

The team also incorporated its cool-as-hell flaps into a running shoe prototype. Researchers sewed multiple flaps, curved down, into the bottom of the shoe so the cell-lined layer would face (but not touch) a runner's foot to help reduce sweating and problems associated with trapped heat and sweat, like warts. 

Going forward, the team is hoping to work with sportswear companies; so far, they've synced up with New Balance. But scientists are also looking at commercializing their designs to create moisture-responsive curtains, lampshades, and bedsheets.

As for now, we'd like to get our hands on the heat- and sweat-detecting run suit—blistering outdoor workouts wouldn't stand a chance.