Some thoughts on wearables, BMI, and heart rate monitoring

You'd have to be living under a rock not to notice all the hype around wearables and fitness-related devices, and the recent announcements around Apple Watch help fuel the fire. As a company that's focused on user experience, we are constantly checking ourselves to validate that we're delivering real benefits to the user - using design to solve real problems. If we're not doing that, you get feature creep, or feature bloat, and you start adding functionality that actually detracts from the core purpose of the product. 

As gadget and new tech enthusiasts, we were all excited about trying out the latest wearables. The cold truth is, most of those wearables are now sitting in a desk drawer somewhere, collecting dust. The reason for that is wearables have inherent limitations, and that most of them can't be used for anything beyond passively monitoring generic activity - and even the accuracy of that passive monitoring has routinely been called into question. This is why we believe that baking tech into the actual workout is where smart fitness devices are going.

The dirty little secret behind most wearables is that they have the exact same sensors that are already in your smartphone, simply re-arranged in a wristband or monitor format. There are already a series of gyroscopes, accelerometers, compasses and GPS in your trusty phone - and recent research seems to indicate that your smartphone is actually more accurate than many of the top-selling wearables. 

The U. Penn study:

"Here's Proof That Pricey Fitness Wearables Really Aren't Worth It":

"Smartphones are as Accurate as Wearables - So Why Have Both?":

"Don't bother with expensive wearables - smartphones are just as accurate at monitoring health":

Two of the most popular features of wearables - activity tracking and heart rate monitoring - are actually the most contested in terms of accuracy. While wearables (like your smartphone) can do a decent job counting steps, in real world exercise they run into all sorts of problems.

“Most devices are pretty good for measuring steps taken during traditional activities. Once you start getting outside of that—like elliptical or sports-related movements—it becomes harder to detect actual steps taken.”

"There may be a problem with your fitness tracker: it could be misreporting your pulse. Mine did, though it took a cardiologist to tell me so."

Interestingly, Cnet's study showed that the most inaccurate monitors were the ones worn on your wrist, and with good physiological reason - by the time blood gets to the capillaries in your wrist, they've already slowed down significantly, and those readings are especially inaccurate when you're engaged in active exercise and your heart rate is up. In fact, one of the few devices to accurately monitor heart rate was the Galaxy S5 - and that's because it uses a fingertip scanner. Unfortunately, the optical wrist sensors that have plagued most wearables look to be the same deployed in Apple Watch, though we're hopeful they've been improved somehow.

So wearables don't really provide any functionality beyond what's already in your smartphone, and when it comes to exercise and fitness monitoring, their accuracy is dubious at best. And some of the claims they're making seem to be tied into metrics that aren't very sound either - like BMI (body mass index). 

"For years, scientists have said that BMI can’t distinguish between fat and muscle, which tends to be heavier and can tip more toned individuals into overweight status, even if their fat levels are low."

"Take for example, basketball player Michael Jordan: When he was in his prime, his BMI was 27-29, classifying him as overweight, yet his waist size was less than 30."

"Top 10 Reasons Why the BMI is Bogus"

Smart Rope and the Smart Gym mobile platform uses BMI only to estimate calories burned during your workout - not as an indicator of health or fitness progress. We take your height and weight and calculate how many calories you're burning based on the number and speed of your jumps, based on CDC guidelines for jump rope. This way, we're not jumping to inaccurate conclusions based on your heart rate, and we're not just passively monitoring your movement -we're using the actual workout and the actual fitness device itself to accurately track the benefits of your workout routine.

We're hopeful that wearables will continue to improve and that somehow they'll get around the physics and physiology problems. But until they actually provide the user with tangible benefits (beyond what's already in your smartphone), we see far more utility in making your real exercise smarter. For passive monitoring and tracking information that's less than useful, you can always rig up your office to track how much coffee you're brewing and how often you're flushing the toilets: