Scientists Tested 12 Fitness Trackers. Heres What They Found

March 31, 2017 • Blog Post • BY SUE POREMBA


  • Scientists at the National Institute of Health and Nutrition in Tokyo tested the accuracy of 12 fitness trackers and found serious discrepancies
  • The security concerns associated with all of the personal data being collected are less discussed but still troubling

Fitness trackers can help keep you moving, but its essential to be aware of their accuracy and security risks

For health-conscious people, fitness trackers are the best thing to happen since scientists said wine and coffee have health benefits. Fitness trackers today not only count your steps but also have online platforms to help people set goals, count calories, record sleep behaviors and monitor heart rates. Users can also pair fitness trackers with popular fitness apps or other apps designed for weight loss.

However, as ubiquitous as fitness trackers have become, users should understand two critical issues: their accuracy is questionable and they know way too much about you.

Accuracy issues

Scientists at the National Institute of Health and Nutrition in Tokyo decided to test the accuracy of twelve of the most popular fitness tracker brands. Participants in the study wore all 12 styles at the same time for approximately two weeks. Researchers found serious discrepancies in the calorie count in both directions, overestimating or underestimating calories by hundreds. The results are troubling because when fitness trackers overestimate exercise, people who need more exercise to maintain or lose weight might get too little activity, increasing their risk for obesity and other chronic health problems, reported.

Other studies found that fitness trackers with heart monitors also arent as accurate as users think. For example, citing a California State Polytechnic University, Pomona study, CNET stated, The study found an average difference of 20 beats per minute between Fitbit devices and an electrocardiogram when used at moderate to high exercise intensities. The researchers said the devices cannot be used to provide a meaningful estimate of a user's heart rate.

What about measuring sleep behavior?

For many, the ability to track sleep behavior is one of the biggest selling points of fitness trackers as its becoming increasingly clear how big a role good sleep habits play in overall fitness. However, the news isnt good for fans of the sleep monitoring capabilities of the trackers. When it comes to sleep, existing trackers and apps arent very accurate at all, according to Hugo Mercier, CEO of Rythm, whose company studies sleep quality and is developing a sleep-focused tracker.

The primary way to measure sleep is by capturing your brainwaves (EEG), which isnt reflected in physical movement, Mercier explained. Other elements that play a role in tracking include your heart rate (ECG), eye movement (EOG) and general movement (EMG). Measuring movement from your wrist versus your head makes a big difference. Although todays fitness trackers do come with advanced sensors, they arent equipped with the right technology to monitor sleep.

Security concerns

Unless your health is dependent on fitness tracker readings, the lack of accuracy shouldnt be too worrisome. The security concerns, on the other hand, are less discussed but more troubling. Fitness trackers, like all devices that make up IoT, rely on Internet connections to function properlysome trackers more than others, it should be notedand they are collecting and storing a lot of sensitive and personal data.

This data could potentially be sent back to the vendor of the device or of the software that runs on it. The vendor might share this information with others, said Sven Dummer, senior director of product marketing at Loggly. Data about your location and physical activity, combined with the bio data many of these devices are able to collect, might be worth a great deal to health providers or insurance companies, and this may not be in your best interest.

What you can do to protect yourself

The data these devices generate and log need to be well secured, not only because it might be personal and private, but also because it might contain technical information that could allow hackers to intrude other devices and systems that you own, Dummer added.

In general, it is a good first step to simply be very aware of the fact that these devices might leak sensitive data, he advised. Once you own a device, make sure to keep its software updated (just like you should do on your laptop or desktop computer), make use of the security features the device offers and make sure your passwords and PINs cant be easily guessed.

By employing common sense habits for exercising, diet and security, fitness trackers can be a wonderful tool to keep users movingor at least thinking about their activity levels.