Researchers Test Accuracy of Fitness Bands

Fitness bands make it easy for anyone with weight loss or other health goals to track their physical activity and calories burned. The bands, like any accessory, come in a variety of shapes, colors, and sizes, but an Iowa State University study found not all devices are created equal. Researchers tested eight different activity monitors to determine the accuracy of each model.

Gregory Welk, a professor of kinesiology, says a majority of the devices provided reasonably accurate estimates (within 10% to 15%) of calories burned. The BodyMedia FIT was the top performer with a 9.3% error rating, which is comparable to research models, Welk says. The Fitbit Zip and Fitbit One were next with a 10.1% and 10.4% error rating, respectively. Here is how the other monitors performed: Jawbone Up (12.2%), Actigraph (12.6%), Directlife (12.8%), Nike Fuel Band (13.0%), and Basis Band (23.5%).

Welk says activity monitors were once a tool used only by researchers. Now the market has exploded in response to consumer demand. The monitors can be a motivational tool for some, while others like the convenience for tracking. Researchers know that people tend to overestimate their activity levels, so it is important that the monitors are accurate to eliminate that human error.

“People buy these activity monitors assuming they work, but some of them are not that accurate or have never been tested before. These companies just produce a nice-looking device with a fancy display and people buy it,” Welk says.

To test the devices, 30 men and 30 women wore all eight monitors during a 69-minute workout that included a series of 13 different activities, ranging from writing at a computer and playing Wii tennis to playing basketball and running. Participants also wore a portable metabolic analyzer that researchers used for comparison to test the accuracy of each device.

The research, published in  Medicine & Science in Sports & Exercise, assessed how the devices performed for a sustained period of monitoring, instead of evaluating individual activities, to better reflect how they would perform in real-world conditions. Welk also points out that the monitors, regardless of accuracy, cannot guarantee results in reaching fitness goals, and what works for one person may not work for another.

“The point that a lot of people miss is that they think these devices will solve their activity problems and make them active on their own,” Welk says. “The device can be a nudge or a prompt, but it is not going to make them more active unless they change their behavior and learn from their experience. A $25 pedometer is as good of a behavior change tool as a FitBit.”

Source: Iowa State University

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