They're plastic or rubber, plain, and thin.  Most are black or varying shades of black.  They live on the wrist, like a watch, but you can find them woven into clothes, buried in shoes, socks and bras.  They're like a pedometer only much, much cooler.  It can tell how well you slept, but not with whom. It can rat on you to your friends when you've been a bit lazy.   

They are called activity tracking devices--digital monitors that are worn like a bracelet or cuff, like Fitbit, Jawbone and Polar Loop.  Unlike the pedometers of old, these have accelerometers, which can track the movement up/down, side/side and forward/backward.  Made so small, they can be embedded in almost anything,  They are adding a variety of additional sensors, like armbands that measure perspiration and muscle heat, which will give a more accurate reading for activity level and calories burned.  Some measure pulse, resting heart rate, perspiration and skin temperature.  Better yet, by sensing movement during sleep, they can estimate the lengths of fitfulness. 

Used to monitor activity, some wearers track their steps, setting a daily goal of let's say, 10,000 steps.  Ten thousand steps is is a rough equivalent to the Surgeon General's recommendation to accumulate 30 minutes of activity most days of the week. So, at the end of the day and you've only walked 9,234 steps, there's the incentive to put down the PBR, grab the pooch and take a couple of laps around the block.  In addition to daily goals, it helps track progress over weeks and months.  A primary care physician at Massachusetts General studied 10 patients with diabetes and give them a Fitbit Zip tracker.  According to Mr. Larocca, "People felt more knowledgeable" and "Every single person increased their activity."  Up to 8 months later, half of the patients still wore the tracker.  

Oh yes, there're plenty of apps, of course.  You can sync tracker to your phone (or computer) and record your daily stats or workouts.  You can even log the apple fritter you ate before your workout.  As a sleep monitor, it will know when you marathoned watched a season of Breaking Bad.  

There's value in social support, of course. Connecting with Facebook, some trackers  like the FitBit, have (another) app to find friends who are also using the devices.  You can see your friends' workout progress and they can see yours, good or bad.  This may go a ways to helping you keep your goals by having friends cheer you on or give a spirited nudge.  

WebMD says that people who track their exercise are more successful at losing weight.  That's a good thing.  But, do you really need the fancy device or is it just a novelty? According to Dena Bravata, M.D., M.S., a senior medical research scientist at Stanford, the jury is out on whether or not an app or device is better than a good, old-fashioned notebook or pedometer.   She suggests that the only data that actually gets users to change their behavior is the number of steps taken a day and the only tool needed to record progress was a notebook and a $10 pedometer.  

 Want to read some of my previous articles?  You can do it here.  Enjoy.