When Dhananja Jayalath and Christopher Wiebe were students at the University of Waterloo, working towards degrees in electrical engineering, they were also gym buddies who liked to pump iron together. "Exercising can be a very frustrating thing, especially for an engineer, because its really hard to tell how well you're performing during the actual workout," remembers Jayalath. "The next day you'll be sore. Maybe too sore if you worked out more than you needed, maybe not sore enough, if you didn't hit your full potential."

The duo wanted to create technology that could peer inside their bodies and analyze the activity, guiding them to push just the right amount. That dream led to Athos, gym clothes lined with sensors that can sense the activity inside of muscle fibers and track exactly how hard, and how well, your body is working. Today the company announced a $12.2 million round of funding that will allow it to scale up the manufacturing of its gear, which is available now for preorder and will begin shipping in the fall.

The Athos gear works using a technology called electromyography (EMG), which has been commonly used by doctors for decades. When you move, the contraction of muscle fibers emits an electric signal which can be recorded and measured. The average electromyographic unit available in a hospital is bulky and can cost anywhere from $5,000 to $15,000. It has become a more common tool in high-end training facilities and sports medicine, but so far it has not been widely available for the average consumer.

"Exercising can be a very frustrating thing, especially for an engineer."

Athos is hoping to change all that. The company created a new micro-EMG sensor that's woven right into a piece of clothing and can survive your sweat and the subsequent trip through the washer and dryer. The shirt and shorts are $99 each and contain more than a dozen sensors to measure different muscle groups. To make them work you need to shell out $199 for the Core, a tiny Bluetooth device that acts as the brains of the operation, communicating with the Athos app on your smartphone.

Athos isn't alone in mining this old medical technology for new applications as the market for wearable technology explodes. The Leo, a wearable band aimed at cyclists and runners, also uses EMG. "We can actually use these signals to measure your lactic acid levels and alert users before they get a cramp if they are pushing the pace too hard," says founder Leonard MacEachern. "That is something which used to require going to a lab, exercising in a controlled condition, and having blood drawn, which would then be tested. Now we can show you what's happening inside your body, in real time, and on your smartphone."

"A much less expensive version of a personal trainer."

The main difference between the Leo and Athos is that the latter looks at how muscle groups across your whole body are working together, or not. Let's say you're doing a bench press. The Athos gear can see which muscles fibers are exerting the most and and alert you if a weakness in one part of your body is hindering another. "With a bench press, if your shoulders are overtaxed, you're not going to be able to engage your chest and use the larger muscle groups to their full potential," says Jayalath. Along with examining which muscles are contracting and to what degree, Athos will measure your heart rate, and if you're wearing the shirt, your lung capacity and breathing patterns. "The goal is to give you real-time feedback that will allow you to fine-tune your workout and avoid injury," says Jayalath, "a much less expensive version of a personal trainer."