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Wearable activity monitors easily fooled

Pat Hagan, February 8, 2017 5:45PM Herald Sun

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THEY are the must-have gadgets for the health-conscious* striving to walk 10,000 steps a day.

But new research suggests activity monitors such as Fitbits may be over-estimating* the number of steps users take by up to 25 per cent.

In tests, some gadgets registered* steps when volunteers were sitting at a desk typing or standing still washing dishes or stacking books.

The gadgets contain a tiny device called an accelerometer* to detect motion, with the number of steps often based on counting arm movements forwards and backwards, which can be deceptive*.

Findings from the National University of Ireland in Galway suggest some users who think they have racked up the recommended 10,000 steps a day — roughly 8km — may actually have achieved only 7,500.

The Rise of the FITBIT media_cameraKelly Shepherd exercising at Bondi Beach with her Fitbit. Picture: News Corp

Researchers filmed 37 men and women and compared readings on five different devices with the activity actually done.

The results, published in the Public Library of Science journal PLOS One, showed a Jawbone UP device registered a false positive — counting a step when there isn’t one — up to 25 per cent of the time, and a Fitbit One about ten per cent of the time. They noted: “All monitors registered a significant number of false positives.”

Sales of fitness trackers have soared in recent years. In 2015, people bought 78.1 million wearable fitness devices around the world. Worldwide sales were estimated to be around 102 million for 2016.

Professor Ian Swaine, head of sports science at Greenwich University in the UK, said that even though technology is improving, fitness trackers can only ever give an estimate. But he added that they still encourage exercise. Fitbit said its trackers “are not intended to be scientific or medical devices” but monitor* “overall health and fitness trends” to help users get in shape.


health-conscious: thinking about health

over-estimating: guess or suggest a number that is too high

registered: recorded

accelerometer: measures the acceleration of a moving body

deceptive: misleading

monitor: observe, check, record information



Activity 1: Persuasive Writing

Now that you know that activity monitors can be quite inaccurate, what do you think about them? Do you think that they fool users into thinking they have done more activity than they really have, or are they still a useful tool? Write a persuasive essay to explain your point of view.

Extension: Re-read your piece of writing and make at least one change to each of your arguments to help make them more persuasive.

Time: allow 40 minutes to complete this task

Curriculum links: English

Activity 2: Maths Problem Solving

Solve the following maths problems. You may use a calculator to help you but should still write down what you did to work them out.

1. How many more fitness monitors were sold in 2016 than in 2015?

2. If sales increase by the same number again in 2017, how many will be sold?

3. What was the total number of activity monitors sold in 2015 and 2016?

4. If 10,000 steps is equal to 8km (8000m), how big must one step be?

5. Imagine you have taken 5000 steps in a day. If your Fitbit One added on an extra 10 per cent, how many steps would it say you took?

Extension: Working with a friend, take a few steps and have them put a counter down at each spot your heel lands. Measure your steps and decide on an estimate of how long one of your normal steps usually is. Now calculate the distance you would walk in a day if you took the recommended 10,000 steps.

Extra resources

Calculator, metre ruler or tape measure

Time: allow about 30 minutes to complete this task

Curriculum links: English, Mathematics

VCOP Activity

(Vocabulary, Connectives, Openers and Punctuation)

Activity 1: Verb Challenge

A verb is an action or doing word. In pairs make 4 mind maps with 4 different sports in the middle. Now together try and come up with 3 verbs/actions/doing words you might do during each sport.

Extension: Swap with another group and see if you can add a new verb to each of their sports.

Time: allow at least 15 minutes to complete the task

Curriculum Links: English, Big Write, VCOP

Activity provided by Andrell Education






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