Study finds iPhone health app miscounts your daily steps

Ever find yourself a few steps shy of hittingthe 10,000 mark? Turns out your smartphone might be holding you back.

The popular iPhonehealth app isn'tthe most reliable personal trainer, according to anew study from the University of British Columbia.

Researchers found that the iPhoneappcanunderestimate the number of steps taken in a day by as much as 20 per cent.

"Any time you're measuring something, there's going to be a little bit of error," saidMark Duncan,PhDcandidate at UBC's School ofKinesiologyand lead author of the study.

But sometimes, it's not the technology itself that's entirely to blame.

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Two separate tests

Duncan's study used 33 participants and was divided into two parts: a lab test, and a test in ordinary living conditions.

In the lab, participants walked on a treadmill. Their steps were both manually counted andtracked using twoiPhones a personal phone, and a lab phone.

"At lower speeds, [the iPhones] were less accurate, missing about nine to ten per cent of steps," said Duncan.

However, the gapnarrowed at speeds above five kilometres per hour, missing less than five per cent of steps, a figure that Duncan says is more in line with traditional pedometers.

A 20 per cent gap

But the greaterdiscrepancy occurred in the second phase of the study, whenparticipants tracked steps outside the lab.

In addition to keeping their phones on while they went about their daily routine, they also wore fixed accelerometers around their waists for three days, whichtracked how fast and how far they moved.

According to the study, the iPhone underestimated the accelerometer data by an average of 21.5 per cent, or 1,340 steps per day.

Duncan says the gap is significant but the iPhone might not be entirely to blame.

"A lot of that could be attributed to people not necessarily bringing their phones with them, or carrying them in their [backpacks]instead of on their persons like in their hands, or in their pockets."

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Leaving your phone behind when you make a trip to the bathroom, or run out to grab a coffee at work, seems to be where the error stemsfrom, Duncan says.