All of the instructions and code were made available in the hopes this will help speed up development. You can't buy this new wearable, but you can make it yourself. The research paper also encourages smartwatch engineers to use its method to improve calorie tracking effectiveness. 'Maybe using an IMU in your smartwatch to get that arm motion, if you're doing a rep you could perhaps use the same modeling approach,' he says. 'People can't necessarily just scale the smartwatch estimates by a fixed amount to make them accurate for everyone,' he says.įor now, this leg-based system only works for lower-body exercises, but he's already thinking of ways to make a version that can also take into account upper-body movement like weightlifting. Turns out the watch was underestimating my overall calorie burn during each exercise, but Slade tells me it could overestimate for someone else. You can see the rest of the calorie counts per exercise in the video on this page, but across all four workouts, the leg wearable error rate was 14% compared with 58% from the watch on my wrist. For running, the respirometry device said I burned 87 calories, the leg wearable 66 calories and the smartwatch 52 calories. The results are in - and they're surprisingĪfter gathering all the data points from each device, Slade walks me through the results. I know I'm not going to be setting any pace records with all these tools strapped to my body, but fortunately that doesn't matter - we're only tracking energy expenditure. Once we get a baseline reading from the respirometer, I start working out. After my workouts, we'll compare results from all three devices. It costs tens of thousands of dollars and weighs about 5 pounds complete with mask and backpack, so it's not really the best tool for people to use outside the lab.įinally, I strap a smartwatch to my wrist to get its calorie estimations. This monitors the carbon dioxide I breathe out and the oxygen I breathe in to give me what Slade calls the 'ground truth' reading, or my actual calorie burn. I also put on a lab-grade respirometer to measure my actual energy expenditure.

It feels like I have a small smartphone strapped to my midsection and I don't even notice the wires running down my legs. You strap two stretchy bands with the IMUs on your thigh and shin, then wrap a controller and battery around your waist. Putting on Slade's system is straightforward. I'll be doing four workouts for 5 minutes each: walking, running, cycling and stair stepping. But for the purposes of testing out this new wearable, only regular gym machines like a stair climber and exercise bike are needed. To test its accuracy for myself, I've come to Stanford University's human performance lab, filled to the brim with a range of sophisticated workout equipment including an antigravity treadmill.

Most accurate calories burned tracker