Workout of the Week: Tracking Effectiveness of Activity Trackers

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Fuel Band, Fitbit, Misfit - it seems just about everyone has an activity tracker these days. Some people have two or three.

The activity trackers record everything from your daily steps to your calorie burn.  But the question is: How accurate are they?

Some Iowa State University researchers have the answer.

56 people participated in a study to determine the accuracy of four consumer fitness trackers and two research models.

"The key difference in this study is that we've now tested some of the monitors worn on the wrist, instead of the waist," says Greg Welk, a kinesiology professor.

Researchers have known that accuracy varies greatly from model to model. But this study examined the accuracy of the activity trackers during various activities.

"It does the best for activities like walking or running. It doesn't do good at resistance training and that's because you're using your arms in different ways and we knew that, but we wanted to quantify the amount of error in a device," says Welk.

Each of the study's participants was asked to perform 20 minutes of a sedentary activity, such as working on a computer, followed by 25 minutes of aerobic activity and 25 minutes of resistance training.

The overall results show the research grade monitors were most accurate. The Body Media Core and the Actigraph GT3X had an error rate of 15.3 percent and 16.7 percent, respectively.

The Fitbit was the most accurate consumer model with an error rate of 16.8 percent. The Nike Plus Fuel Band SE followed with an error rate of 17.1 percent. The Jawbone UP24 had an error rate of 18.2 percent and the Misfit Shine had a 30.4 percent error rate.

That may seem like a lot, but Welk says there may be another benefit to wearing an activity tracker.

"The average consumer just wants to use it for prompting them for being more active and promoting behavior, and accuracy doesn’t matter as much there as accountability."

In other words, activity trackers may provide you with the motivation you need to move.

"They connect to social media, have a display on your phone, nudge you and buzz when you’re not doing enough steps, beep when you do something good," says Welk. "From a consumer perspective, I think that’s the key."