All three of the devices accurately measured energy expenditure when the volunteers walked briskly, Dr. Meckes and his colleagues found; their estimates closely matched those of the oxygen-consumption monitor.
But the devices were far less reliable in tracking the energy costs of light-intensity activities like standing or cleaning, often misinterpreting them as physical immobility. Only the calorie cost of typing was overestimated, and only by the armband monitor, which considered the arm movements involved to be far more dynamic than they actually are.
These miscalculations echo those of the findings from several other new studies. One, also reported at the sports medicine meeting, involved 74 adults, young and old, who wore an armband accelerometer and a portable oxygen-consumption gauge while walking, jogging, riding a stationary bicycle, windmilling an arm ergometer, and completing so-called activities of daily living, like lifting boxes and sweeping.
The study also found these devices to be “terrible” at accurately measuring bicycle pedaling, one of my own personal favorite physical activities. Here’s more from the article:
The question, of course, is whether it matters if the devices are inaccurate, especially if they underestimate daily energy expenditure, and perhaps fiendishly spur some at-home users to move more, thinking that they’ve expended less energy than they actually have.
The studies’ researchers think the inaccuracies do matter. “There’s a growing consensus” among exercise scientists, Dr. Meckes says, “that people should spend less time in sedentary activities, like sitting,” and instead stand up, stroll or sweep more. But if people get the idea from their activity monitors that such activities don’t really count, in terms of movement and calorie expenditure, “it may be harder to get that message across,” he says.
However, here is another key excerpt from the article and basically the upshot for us at DE:
“They may not be accurate” for counting calories, he says. “But for many people, they’re inspirational, and if using one gets someone to move more, then as far as I’m concerned, it’s serving a good purpose.”
We at DE believe the big question will be to determine which tools give you, your friends, family, and colleagues the biggest bang for your buck in terms of providing the necessary “nudges” to start, and stick with, a regular fitness routine? Oftentimes, pricier, more complicated routes aren’t the best ones to take or even necessary. So, why not try a simpler, more affordable route to good health by starting one of our fun fitness challenges?