Do Wearable Activity Monitors Work?

Believe it or not, there was a time when people actually memorized important phone numbers. Barbaric, I know. But cell phones have quickly progressed beyond the point of simply storing numbers and allowing you to play rudimentary forms of classic arcade games. In fact, we are becoming more and more dependent on our phones for just about everything. They plan our days, map out our drives, entertain us and – increasingly – coach use through our workouts.

What began with a few simple apps on our phones that followed our runs with GPS or acted as a workout log, has advanced to the the point that we can now wear a companion device that expands your phone’s built-in senses. Depending on the wearable activity monitors that you’re looking it, you can receive a wide range of feedback and coaching on any type of activity. In fact, many people simply wear the sensor all day to motivate them to keep moving. This rapid rise in popularity begs an obvious question: Do wearable activity monitors actually work?


Defining Your Expectations

As is often the case with matters of fitness, whether or not a device “works” depends on what you expect it to do. Generally, people hope to do get at least one of the following perks out of their use of wearable activity monitors:

  • Calorie Expenditure Reports
  • Motivation
  • Sleep Quality Reports

So, let’s deal these one at a time.


Calorie Expenditure

The accuracy of consumer level calorie-counting devices has been under scrutiny for a long time and has been called into question by many studies. Depending on where on your body the device is placed and what sort of activity you’re doing, your calorie expenditure could be totally over- or under-estimated. For instance, one study found that wristband style monitors (by far the most common for personal use) overestimated the amount of calories it took the wearer to type but misunderstood cleaning for just standing around.

A more recent study, in the journal Medicine and Science in Sports and Exercise, looked specifically at the margin of error of some of the most popular wearable activity monitors. The following is what they found, ranked from most accurate (lowest percentage of error) to least (highest error rate):

  1. BodyMedia FIT: 9.3 percent
  2. Fitbit Zip: 10.1 percent
  3. Fitbit One: 10.4 percent
  4. Jawbone Up: 12.2 percent
  5. ActiGraph: 12.6 percent
  6. Directlife: 12.8 percent
  7. Nike FuelBand: 13 percent
  8. Basis Band: 23.5 percent

It should be noted, though, that these monitors are constantly getting better and more accurate. But, even if the the reports are a little off, these devices could serve another purpose.



For many people, it doesn’t actually matter how accurate the calorie expenditure reports are, as long as they see some hard evidence that they’re doing something. And, in that respect, wearable activity monitors can be very useful.

The exact strategies used will differ from product to product but a recent study published in the Journal of Internet Medical Research found that these monitors typically make good use of proven motivational tools. Very often, some form of social support and reward system is included, in addition to the expected feedback about heart rate and calorie burn.

The study did note, though, that the effectiveness of the monitors is reduced to nothing if they aren’t being used. For that reason, it’s important for you to pick one that you like to use and can easily understand. You should also take into account the needs of your activity. If you’re a swimming, for example, you’re going to need a water-proof monitor.


Sleep Quality Reports

This may not seems like something you would care about on an activity monitor but the feature is becoming increasingly common. The idea behind it is that quality sleep is key to the recovery process and lack of sleep can make it harder for you to reach your goals. By providing feedback about the quality of your sleep and your various sleep cycles, these monitors claim to be able to help you improve your sleep patterns.

In various studies, these monitors have been found to both under- and over-estimate the amount of sleep the wearer got. When it comes to measuring sleep stages, such as REM sleep, there really is no way for these devices to do that accurately without monitoring brain waves, eye movement and muscle tone. A few monitors, such as Basis, claims to be able to track sleep stages by monitoring your heart rate but experts are skeptical about this technique and no independent research has been published on it’s accuracy.


The Bottom Line

So, do wearable activity monitors work? Sort of.

If you’re looking for a tool to help keep you motivated and give you a decent idea of your calorie expenditure, wearble monitors could be your answer. However, if you’re trying to improve your sleep routine, they probably won’t do you much good at this stage in the game.








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About jonathan.thompson

Jonathan Thompson is a Certified Personal Trainer and Running Coach with the American Council on Exercise, specializing in nutrition. In addition to his real-world experience working with clients, his articles and blogs on fitness advice have been published on many websites and magazines.