Featured Research

from universities, journals, and other organizations

Accuracy of fitness bands tested; reserachers find way to correct self-report errors

Date:
June 9, 2014
Source:
Iowa State University
Summary:
Researchers tested eight different fitness bands to determine the accuracy of each model. The activity monitors make it easy for anyone to track their physical activity and calories burned, but researchers found not all devices are created equal. "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," said a researcher.

The work continues. Gregory Welk (right) and doctoral students Youngwon Kim (left) and Yang Bai (center) are now testing the accuracy of the latest fitness bands on the market.
Credit: Bob Elbert

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 percent) of calories burned. The BodyMedia FIT was the top performer with a 9.3 percent error rating, which is comparable to research models, Welk said. The Fitbit Zip and Fitbit One were next with a 10.1 and 10.4 percent error rating, respectively. Here is how the other monitors performed: Jawbone Up (12.2 percent), Actigraph (12.6 percent), Directlife (12.8 percent), Nike Fuel Band (13.0 percent) and Basis Band (23.5 percent).

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 said.

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 the journal 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 said. "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."

Welk's former Ph.D. student Jung-Min Lee, now an assistant professor at the University of Nebraska-Omaha, conducted the study as part of his dissertation research. This work also demonstrated the potential of calibrating the built-in accelerometers in cell phones for use as activity monitors. This component of the study was presented at the American College of Sports Medicine conference in May. Current Ph.D. students Yang Bai and Youngwon Kim are continuing to advance this line of work.

Improving science by correcting for recall errors

Activity monitors are also widely used by researchers to study physical activity behavior. Welk and his team frequently use research-grade monitors to try to improve the accuracy of self-report measures widely used for public health studies. One of the fundamental challenges with self-reports is that people have a hard time recalling their activity. Welk says there is a lot of interest in reducing this error to provide more accurate results and improve the quality of programs developed from the research.

A team of Iowa State researchers, led by Welk, conducted a four-year study to measure and correct for human error based on people's weight, age, gender and socioeconomic status. The study, funded by a National Institutes of Health grant, included 1,500 people who wore a monitor for a day to track their activity. The following day they completed a phone survey about their activity for comparison.

"We know that overweight people are more inclined to overestimate their activity than normal weight people, because it's harder for them or they're not used to doing as much physical activity. We know the same is true for diet that people tend to underestimate what they eat," Welk said. "The key innovation of the project is that we're using the data we have to understand the error in order to quantify and model the error and correct for it down the road."

The research led by Welk, Sarah Nusser, current vice president for research and professor of statistics; Alicia Carriquiry, Distinguished Professor of statistics; and a team of doctoral students, Bryan Stanfill, David Osthus, Youngwon Kim and Andres Calabro, is generating interest from the National Cancer Institute and other research groups. The study is also published in the journal Medicine & Science in Sports & Exercise.


Story Source:

The above story is based on materials provided by Iowa State University. Note: Materials may be edited for content and length.


Journal References:

  1. Jung-Min Lee, Youngwon Kim, Gregory J. Welk. Validity of Consumer-Based Physical Activity Monitors. Medicine & Science in Sports & Exercise, 2014; 1 DOI: 10.1249/MSS.0000000000000287
  2. Gregory J. Welk, Youngwon Kim, Bryan Stanfill, David A. Osthus, Andres M. Calabro, Sarah M. Nusser, Alicia Carriquiry. Validity of 24-h Physical Activity Recall. Medicine & Science in Sports & Exercise, 2014; 1 DOI: 10.1249/MSS.0000000000000314

Cite This Page:

Iowa State University. "Accuracy of fitness bands tested; reserachers find way to correct self-report errors." ScienceDaily. ScienceDaily, 9 June 2014. <www.sciencedaily.com/releases/2014/06/140609102646.htm>.
Iowa State University. (2014, June 9). Accuracy of fitness bands tested; reserachers find way to correct self-report errors. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2014/06/140609102646.htm
Iowa State University. "Accuracy of fitness bands tested; reserachers find way to correct self-report errors." ScienceDaily. www.sciencedaily.com/releases/2014/06/140609102646.htm (accessed July 25, 2014).

Share This




More Health & Medicine News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Newsy (July 24, 2014) Sheik Umar Khan has treated many of the people infected in the Ebola outbreak, and now he's become one of them. Video provided by Newsy
Powered by NewsLook.com
Condemned Man's US Execution Takes Nearly Two Hours

Condemned Man's US Execution Takes Nearly Two Hours

AFP (July 24, 2014) America's death penalty debate raged Thursday after it took nearly two hours for Arizona to execute a prisoner who lost a Supreme Court battle challenging the experimental lethal drug cocktail. Duration: 00:55 Video provided by AFP
Powered by NewsLook.com
Can Watching TV Make You Feel Like A Failure?

Can Watching TV Make You Feel Like A Failure?

Newsy (July 24, 2014) A study by German researchers claims watching TV while you're stressed out can make you feel guilty and like a failure. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins