Fitbit accuracy controversy

OLYMPUS DIGITAL CAMERAI came back from a long walk, and my Fitbit registered 11560 steps.  Great!  Then I was greeted by screaming headlines suggesting maybe that number was wrong:

Study claims Fitbit trackers are ‘highly inaccurate’.

Fitbit devices are inaccurate!

Fitbit accuracy questioned in lawsuit.

I read through the stories, and breathed a sigh of relief: my step count was reliable after all.  What the headlines don’t tell you is that the alleged Fitbit inaccuracy is for heart rate, not step counting.  The helpful lawyers behind this lawsuit filed it on behalf of all those people who bought a Fitbit to measure heart rate.  People do that?  I thought the main purpose was step counting; heart rate and other measurements, like energy expenditure, are nice but not the main point.  We are told to get 10,000 steps a day for health.  Step counters like Fitbit act as handy reminders (or nagging reminders) to get up and move.

The lawsuit is based on a study funded by the same lawyers filing the suit, comparing the Fitbit heart rate data to a different heart rate sensor.  The Fitbit was off by about 20 beats per minute during moderate-high intensity exercise.  Fitbit’s response: the tracker is not sold as a medical device.

Heart rate monitoring on exercise devices like treadmills isn’t very accurate either, so I’m surprised those companies haven’t also been sued.  I attempt to measure heart rate on stationery bikes and treadmills, using the hand grips.  Usually they just blink at me; I may get a number 25% of the time, and it’s usually a number that’s off base compared to actually counting my pulse myself.  I don’t really care, but some people may have heart rate goals, or cut-off points, so an inaccurate measurement could be problematic.

A study of Fitbit and Jawbone devices published last year found that they were accurate for step counting but less accurate for energy expenditure and distance traveled.  Sometimes energy and distance were over estimated, sometimes under estimated.  But which is it for your particular device?  And will you then adjust your diet accordingly, but inaccurately?  Lawsuit anyone?

Am I going to ditch my Fitbit?  No. I use it as a step counter. Period. For that purpose, it’s reasonably accurate.  Eventually technology may improve so we can get 100% accurate measurements of everything all day long.  We’ll have a lot more numbers to deal with, but I’m not sure that’s going to make life better.

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