This Is What It’s Like To Wear Smart Spandex During A Workout

By building EMG sensors into compression gear, Athos wants to put a high-tech fitness lab in your pocket.


“Before you go change, just remember one thing,” says Athos cofounder Dhananja “DJ” Jayalath, handing me a pair of used spandex shorts. “All the sensors have to touch your skin.”


We’re inside a luxurious private gym on the fourth floor of Manhattan’s London Hotel, surrounded by a swarm of unused treadmills and stationary bicycles. I take a hard look at the shorts, freshly laundered, noting the electrical sensors stitched into the material. “So, go bare butt?” I ask, a little confused.

“Go bare butt.”

In the bathroom, I squeeze into the $100 compression shorts as if they were sausage casings and emerge ready for my workout. My goal that afternoon was to assess Athos’s forthcoming “smart” line of workout gear, which are designed to shrink the athlete-sculpting data of a high-tech fitness lab into skintight spandex. You know that training montage in Rocky IV? The one where the Russians have Drago wired into a million different machines while a bunch of suits politely clap for him on a treadmill? Athos is that, but instead of Cold War-era technology, it’s just some clothes and an iPhone app. You are Dolph Lundgren.

By all appearances, the shorts look like your run of the mill compression gear that Nike, Under Armour, and Adidas sell to gym rats. Inside, though, are eight electromyography (EMG) sensors, which measure the electrical output of your muscle cells, and four other sensors that keep tabs on your heart rate. Each EMG is positioned over a corresponding muscle group: Your hamstrings. Your inner- and outer-quads. Your glutes.

The suit is powered by a small egg-shaped Bluetooth gadget that plugs into the spandex called the Core, which you’ll have to buy separately for $200. This Core wirelessly transmits real-time feedback to your smartphone to show you how hard (or not hard) your muscles are actually working. The idea is to use the feedback to optimize your workout so that you can build muscle properly and keep injuries at bay.


Athos was founded in January 2012 by Jayalath and Christopher Wiebe, who became fast friends as engineering undergrads at the University of Waterloo in Canada. As freshmen in 2007, the two found common ground in their “masochistic approach” when it came to their studies and, like most college bromances, getting hammered after the fact. More importantly, though, the two shared an affinity for hitting the gym. “We would to go the gym together and it was always competition,” says Jalayath. “How much weight are you doing? How much harder could we go? Stuff like that.”

With a few hardware design internships under their belts, the two eventually stumbled on what they considered to be a bright idea: What if, instead of an expensive personal trainer, you could take one with you anywhere inside of your smartphone? And not just an app told you what kinds of exercises to do; there are already a ton of those. But something smart–something that could tell you with precision what you’re doing wrong. And sensors! What if it had sensors!

The goal was to provide users with “glanceable awareness” during their workouts, says Wiebe, to give a wearer real-time feedback. While including biometric sensors in smartwatches and other wrist junk might be confusing or unnecessary for the average user, engineering those same capabilities into the clothes people wear to the gym makes a bit more sense. A new breed of heady fitness geeks–who Jayalath and Wiebe just so happen to exemplify–eat this kind of feedback up.

“That was definitely the main focus when we started. We designed the prototype and experience around this real-time view on the moment.” In early 2012, Wiebe and Jayalath put together their first prototype, and Athos was born. (In addition to compression shorts, the company also makes a sensor-equipped workout shirt that’s also $100.)

Here’s how their system works. Once you squirm into the spandex and calibrate the average electrical output of your muscles in the app (with the shorts, this is accomplished by walking up a few stairs), you are given a few “muscle effort” targets that you try to hit, number percentages that indicate how hard you’re pushing yourself. Want to merely burn fat? Something like 55% should do. Want to build lean muscle? You’ll need to work harder, so let’s shoot for the mid-60s. Everyone’s target number swill be different, depending on the shape you’re in.


While trying out the app with a leg press workout and actually going through a few sets of 10, I learned a few things about my technique that I would have never known otherwise. Essentially, everything I was doing was wrong.

For starters, the muscles on my right side were firing much harder than the muscles in my left. My right quadricep was overcompensating, taking the brunt of the workload. That might not sound very dangerous. But over the course of months or years, that sort of muscular imbalance can lead to serious injury. Once I made a conscious effort to redistribute my weight properly (when the regions in both thighs were glowing the same yellow color on the iPhone screen), I was back on the right track. Destination: Sick-Quad City.

That said, there are limitations to the technology, but they’re limitations that the Athos team is very much aware of as it gears up for a November launch. For starters, the app itself isn’t very smart yet. While it can tell you which muscles are firing and what targets you need to hit, the A.I. can’t contextualize that data like a knowledgeable personal trainer can. It can’t bark out how many reps you have left, or tell you what kind of newfangled twisting dead lift variation you should be doing. When pressed for details about future plans for the app, the team was mum. “What we’re launching with our first product is not going to have the full breadth of what we want to do,” says Wiebe. “But we’re moving on the path to becoming that virtual training experience. There are just so many things you can do with the technology.”

Durability has also been a problem that Athos has had to solve. With early prototypes, the big challenge was ensuring that the sensors would stay intact through sweat and friction, especially in the wash. “The washing machine is the most destructive thing I have ever had to come across,” deadpans Jayalath. “Back in the day we used to have these wires that had kevlar in it, and it would shred the kevlar.” (Eventually, Athos got rid of the wires altogether.)

On the bright side, it’s still early for Athos. And with that in mind, the challenges confronting the company are somewhat unique. Athos isn’t a traditional hardware company. Or a software company. Or even a clothing company. Rather, it’s an unholy amalgamation of all three. “If you’re going to build it into clothing, it needs to feel like clothing,” stresses Jayalath. “You have to put it in the wash. You have to crumble it up and throw it in your gym bag.” Good design, at least in this case, means forgetting that you’re wearing cyborg gear altogether.


One day soon, it isn’t hard to imagine when our workout gear will be quantifying every little muscle twitch or yoga pose, giving normal people the same fitness resources as yesteryear’s super athletes. We’ll all know exactly how much weight we should be lifting, how hard we need to be pushing ourselves, and what we’ll need to do to be the tiniest bit better next time. “We want the technology to be integrated into your existing routine,” says Jayalath. “You just put it on, and you’re good to go. You shouldn’t have to do anything special.” Basically, we’ll all be Drago.

More from Wearables Week:

About the author

Chris is a staff writer at Fast Company, where he covers business and tech. He has also written for The Week, TIME, Men's Journal, The Atlantic, and more