Welcome to the Get Fit Guys' quick and dirty tips to slim down and shape up.

My name is Brock Armstrong. I'm the Get Fit Guy, and we're going to dive into the world of wearables,

smart watches, fitness bands, movement trackers, or whatever you want to call them, to find out how much or how little you can

actually rely on them.

You know, cool devices like the Apple Watch, Fitbit, and the nearly ubiquitous Garmin four

runners, at least at my local running group anyway, well, they aim to track your biometrics

like heart rate and calories burned, along with various

other fun variables like pace, vertical oscillation, and elevation.

There are even a few that try to predict your recovery time, your race paces, and even your

V-O-2 max, which would be pretty interesting, especially given the vomit-inducingness of a real VO2 Max test,

if they can be trusted. And that's a big if.

When I got on board with these devices back in 2009, they weren't all that accurate.

Even the cardiologists who studied wearables at Stanford University went as far as to say that they thought of them a little bit like random number generators.

They really didn't seem to be providing anything that was even close to your actual heart rate.

The folks at Stanford have recently tested several newer fitness bands, and now they say those heart rate stats have gotten much, much better.

For most of the devices, the error rate was less than 5%, which is considered medical grade and good enough for your doctor.

Where all the devices fell apart was in estimating the calories burned when they were compared

to the gold standard lab measurements of energy expenditure.

The reason for the discrepancy could be that we all burn energy at different rates, and that's

hard to guess from simple parameters like weight and height, which is generally the only thing that we

tell these devices when we first buy them. I mean, if I just go out and watch the runners in my

neighborhood, some are incredibly efficient and look simply elegant when they run. Watch a video

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