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The importance of accuracy in fitness trackers

6 min read
2 May 2016

It started with the humble pedometer from the 1990s, then evolved to heart rate monitors and calorie counters attached to electronic gym equipment. Now we have an exploding industry of wearable devices that do all of this and more: calories burnt per minute, elevation, GPS tracking, sleeping quality and restlessness, and even pre-timed reminders to get up and stretch your legs. And instead of being hooked up to a bulky device, you get all of this in a stylish wearable band.

So what do we need to be aware of with this new technology?

Fitness AND fashion

Even if you’ve not jumped on the fitness tracker bandwagon yet, surveys tell us that there’s a pretty good chance you will. Roy Morgan found that more than 1.5 million Australians already own a fitness tracker and 785,000 more plan to buy one in the next 12 months. If those intentions come to fruition, we’ll have 2.3 million, or 12 per cent of us, donning the technology.

The benefits of fitness trackers are plain – if you’re monitoring your fitness, it’s easy to set goals, track performance, and assess your overall health. However, according to this article in The Guardian, when it comes to our relationships with our fitness trackers, it’s complicated. In a study from The Conversation, a high proportion of women wearing trackers did more exercise and ate less while wearing a tracker, but almost half reported feeling ‘naked’ without their tracker, and a third said the device made them feel guilty.

Why fitness trackers are great

Let’s look at the upside of owning a fitness device:

  • Good feedback can provide good incentives. Think of a personal trainer telling you there’s only 1 kilometre left and you’re all done. You’ll probably give it one last push. A tracker allows you to be your own personal trainer, using the data to keep setting goals.
  • Seeing a goal approaching, for example the popular 10,000 step-per-day goal, is more likely to result in you reaching that goal. This small survey from found users were more motivated by real-time tracking. The key is engagement – this study from DSpace Institutional Repository showed that the 67 subjects had a greater chance of sticking to their fitness goals if they showed increased engagement with the device.
  • You have metrics over time, which means you can see if you’ve improved, stabilised or dropped off a little. This study, based on mobile-phone fitness apps, explores specific goal-setting as being paramount, so being able to have real time tracking is an essential part of this.

The accuracy of activity trackers

So far, so good, right? Hold that thought. We know this technology is impressive, but is it really as accurate as the manufacturers would have you believe? Evidence has come to light that we may not be getting the best available data on heart rates, steps taken when running and sleep patterns. outlines research done in Japan that measured 19 adults wearing 12 trackers, whilst also being measured by two scientific ‘gold standards’. The results showed that fitness trackers underestimated calories burned by as much as 590 per day. This article from Berkeley Science Review article explains that even the best fitness tracker will probably underestimate calories burned when the wearer isn’t doing anything physical.

All this might seem trivial in context, especially if the tracker is only underestimating calories, after all the outcome is likely that people will burn more calories than intended. However, if people are relying on these devices to seriously track their biometrics, an incorrect reading could be dangerous, especially if the person has cardiac or vascular issues. This study shows 16 different devices were shown to be flawed just in the ‘steps taken’ function.

The other questionable metric belongs to the sleep tracker, which is designed to record your sleep, restlessness and wake times during the night. Given consumers have called into question the accuracy of the reported sleep/wake cycle.

The real question here is – are the devices marketed as scientific devices, and could those who own one assume the data is highly accurate?

Setting goals and staying focussed

If absolute accuracy is not your concern and near enough is good enough – then your fitness tracker can help you achieve your goals, provided you use it correctly. We’ve already shown that the more you engage with your device, the more likely you are to stay motivated, but here are some tried-and-tested ways to get the most out of your tracker:

  • Set reminders. Start with a vibration or text message notice to get up and move your legs every 30 minutes. If you’re busy, settle for a stand-and-stretch.
  • Of absolute importance is making your goals achievable. Study after study shows that realistic goal setting will be the key to sticking with it. Start small and gradually scale it up in line with your current fitness levels.

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  • Make your goals very small and very specific and write down an overarching fitness goal. It might be to walk or cycle to work, take on a hiking challenge for charity, or even run a marathon. Your goals can be as humble or as grandiose as you please. Here are some practical tips from that can get you started.
  • If at first you don’t succeed, then start smaller. Always be realistic about what you can achieve. If motivation is the real struggle, make your goal a walk to the next corner. It may sound silly, but scaling up really does work.

A little bit of mindfulness goes a long way

A final criticism of trackers is that users can become less tuned in to their bodies, and more reliant on a device to relay overall health information. A tracker can give some good insights, but if this is at the expense of listening to the body’s cues then an unhealthy relationship with the body and a tracker could develop. This article from Johnny Adamic at The Daily Beast says just that, advising that we need to manage our relationships with trackers, exercising to make our bodies and minds feel better, rather than to hit numbers and please a machine.

Finally, even if your fitness tracker overestimates your sleep, underestimates your heart rate and wrongly counts your steps by 5%, does it affect your achievements? If you’re walking more, jogging more, sleeping more and feeling in control, whilst paying attention to your body then there is likely to be a place for an activity tracker on your wrist if you decide to join Australia’s growing trend.

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