These new leggings use NASA technology to keep you cool while you work out

Ministry of Supply—a clothing company known for performance-enhanced fabric tech (and one of our favorite masks)—recently added a high-tech version of a pandemic favorite into their lineup: the Joule Active Legging. The black legging features NASA phase-change material, fabric developed to keep astronauts’ suit temperatures at their most comfortable both on earth and in space. The leggings are made from a recycled poly blend and keep odor at bay thanks to a third-party-certified, zinc-based antimicrobial finish. In MoS’s family of versatile, smart apparel (Carbon-neutral dress shirts! Self-fitting sweaters!), the Joule leggings are a natural fit.

I put the Joule into that category of legging where the immediate out-of-box reaction is “There’s no way my body will fit in there.” They’re more substantial than your average yoga pant and feel like slick nylon, with thick stitching down the leg and across two deep side pockets. They are no doubt built for working out, they but feel great on—comfortable, firm compression that stretches and conforms with ease.

The shape is interesting: They’re a 7/8 length, so at 5-foot-2, they hit below my ankle. The combination of pockets that sit closer to the hip and the front stitching gives them a more polished, structured appearance. They wouldn’t look out of place paired with a sweater or button-up. They could probably pass for a ponte pant if it weren’t for the sheen.

For performance, I put my Joule leggings through a two-prong test: one early-morning yoga session and a jog in the deceptively still-cool Boston sun. They were a little too restrictive for my taste in yoga pants. I found myself overly conscious of the compression and stitching against my body. This could be because I typically opt for Lululemon’s lightweight, second-skin Align leggings for my a.m. flow. But I imagine the Joule has a time and a place: Sometimes that “nearly naked” feeling of softer leggings is too nearly naked, on the subway or in an overcrowded class. A tighter, more body-conscious fit may be a fair trade-off for a thicker fabric that hugs the body without feeling too exposed when we get back to socialized workouts.

But they’re great in the outdoors. Boston, where Ministry of Supply is based, has completely unpredictable spring weather. A deceptively sunny day can be freezing by the time you get down the street. The leggings stuck firmly in place for my sprints while keeping me comfortably temperature-regulated for the duration of my experiment, during which the temperature dropped from 60°F to 40°F in a mere hour.

I’d be interested to see how the leggings perform in a sweaty cardio class, since they held up well through all my fidgeting and power walks, and I suspect I can even work them into my wardrobe once the world gets back to “business casual.” A year into the pandemic, I am a leggings connoisseur. I have no patience for bad fits and fabrics, and if the waistband twists or rolls? Get out of here! But I truly believe the Joule is a very cool pair to have in rotation—literally and figuratively.