How accurate are fitness apps?

Every so often something comes along and grabs the popular consciousness; we call it a “fad” but sometimes those fads turn into everyday reality. It might be that activity trackers, those devices that record how many steps you take each day and even how you sleep, have moved out of the fad phase into the daily reality part of life but are they really good at doing what they say they will do? This was what researchers wanted to find out in a new study.

Generally the trackers under-estimated kilojoules burned and over-estimated total sleep time.

To estimate the effectiveness of trackers researchers conducted a detailed review of 22 articles that looked at the ability of two popular tracker brands to measure steps, distance, physical activity, kilojoules burned, and sleep.

Some of the studies showed that the step counting aspect was accurate in the laboratory and in the real world. However, distance travelled tended to be over-estimated at slower speeds and under-estimated at faster speeds. Some studies suggested that physical activity was accurately assessed while others suggested a bit of variance. Generally the trackers under-estimated kilojoules burned and over-estimated total sleep time.

All in all, the trackers were best at step counting and not so good when it came to kilojoule burning and sleep. To get the most from your tracker the researchers recommend that you wear it in the same position each day, enter personal details correctly when setting up, and use whatever personalisations are possible (like calibrating your stride length).

So instead of asking if the tracker is tracking you accurately, you really need to be thinking about who is tracking the tracker.