Can Your Trust Your Digital Fitness Device?
Faculty researcher Alex Montoye recommends the use of digital fitness devices to monitor physical activity. But he warns that they are not perfect and that there are some things they can’t measure.
Long before the digital fitness gadget craze emerged, Alex Montoye ’10 was intrigued by wearable technology. As an athlete, he wore physical activity trackers to set his own exercise goals and monitor his activity. As a scholar, he wondered if he could trust their accuracy as a tool for improving health.
“We know exercise is good for health, but as individuals we don’t always know how much exercise is best,” says Montoye. “We also know people tend to over-estimate their exercise activity. Devices like Fitbit give us a better indication of how much activity is really occurring.”
Wearable trackers are designed to do a multitude of functions. They measure steps, calories, heart rate, distance moved, stairs climbed, quality of sleep and other personal metrics. They come in many brands, sell for varied costs and are typically worn on the wrist, hip or ankle.
“As a wearer of these devices, I became interested at the research level in learning how they function,” he says. “We know they use algorithms to convert raw data into meaningful outcomes. But are some brands of trackers more accurate than others? Are they good only for certain kinds of activities? Does the body placement of the tracker make a difference?”
His research takes many forms. He examines the multiple ways to measure activity, ranging from self-reporting personal diaries — which tend to be the least accurate — to the use of elaborate devices that measure oxygen consumption to calculate the number of calories burned — which are the most accurate but also the most cost-prohibitive. Pedometers or accelerometers are in the mid-range of accuracy and easiest to use and test, says Montoye.
He also tests the various methods of measurement against a wide variety of activities, ranging from sedentary to household to ambulatory/exercise. His findings have attracted national media attention, with articles citing his research in Kiplinger’s Magazine, New York Times and Chicago Tribune.
Grading Tracker Effectiveness
So, what can digital trackers do well?
In general, they measure ambulatory activity accurately, like walking, running and climbing stairs — usually coming within five percent of one’s actual step count, says Montoye. They also measure inactivity well, and they are good at not awarding steps for stationary activity with a lot of wrist movement, such as typing or shuffling papers.
Trackers fall short, says Montoye, when it comes to measuring household chore activity, like cleaning, vacuuming or doing the dishes. According to one of his studies, most fitness bands underestimate the amount of calories burned when doing tasks around the house by 27 to 34 percent. The bands also typically fail to accurately capture one’s steps when pushing a grocery cart, lawn mower or baby stroller.
In his most recent study published last year, he tested three Fitbit models and a Jawbone activity monitor. Currently, he is studying the performance of the Hexoskin, a biometric smart shirt with sensors that measures heart rate, breathing volume, calories burned, steps taken and sleep. In the future, he plans to study other monitor brands, such as the Misfit, Garmin, Xiaomi, Atlas and Apple Watch.
“My experience so far has been that all monitors seem to do well measuring similar kinds of activities, such as walking, running and sitting, and work more poorly for similar kinds of activities, like household chores,” he says. “My guess is that the Apple Watch and other activity tracker brands will share similar strengths and weaknesses.”
His research also compares the effectiveness of digital trackers worn on different parts of the body. Do they measure better on the wrist vs. the hip depending on the type of activity? Do trackers worn on one’s dominant wrist give a more accurate reading?
Sleep time accuracy also is analyzed. How comparable are the measures of people estimating their sleep time vs. Fitbit measures of sleep time?
The Alma Connection — From Student to Faculty
His interest in trackers began when he was a student at Alma double majoring in mathematics and exercise and health science. In addition to his studies, he was a student-athlete who played tennis and ran cross country. Physical activity was — and continues to be — important to him.
After graduation, he continued his studies and eventually earned a Ph.D. from Michigan State University. He returned to Alma for a year as an adjunct instructor, and then spent two years as a faculty member at Ball State University, where he continued his research.
He returned to Alma in the fall of 2016 as an assistant professor of integrative physiology and health science. He and faculty colleague Christopher Aiken have set up the Research in Applied Physiology Laboratory in the Hogan Center.
“I came to Alma as a student because of the small classes and the opportunity to work closely with faculty; these were meaningful distinctions,” he says. “Now, as a faculty member, these same factors appeal to me. I can have an impact at Alma working with students.”
The Most Important Thing: Be active
With the popularity of physical activity trackers, Montoye is frequently asked if wearing them is worthwhile. His answer: Yes, but with an understanding that they are not perfect and that there are some things they can’t measure.
For most tracker-wearers, the exact number of steps logged matters less than the motivation to exercise. The most important thing is to be moving, he says.
“There are both short-term and long-term benefits for physical activity, including the reduction of chronic diseases and improved mental health,” says Montoye. “Many organizations have recommendations for how much activity people should do.”
The U.S. Department of Health and Human Services, for example, recommends 150 minutes per week of moderate physical activity, or 75 minutes per week of vigorous activity.
“About 50 percent of adults self-report meeting those physical activity recommendations; however, when assessed using an activity monitor, only 3 to 5 percent of adults actually meet the recommendations,” he says.
“The majority of the population is not doing enough activity. I encourage the use of physical activity trackers if for nothing else than to promote a healthier life.”