How do Activity Trackers Work?

By Max. D Gray. Updated: May 16, 2017
How do Activity Trackers Work?

Even without specific strenuous exercise, daily life can be physically taxing. However, to protect us from health concerns, a balance of diet and exercise is required. Finding the time to get into shape or simply establish a healthier lifestyle can be incredibly difficult. Staying on top of this regimen can be even more difficult. Knowing how far you travel, how many calories you burn during exercise and charting your progress can really aid your fitness plan. A device known as a fitness band or activity tracker can help do this for you. Activity trackers relay information to a device to help keep track of your fitness, but when asking "how do activity trackers work?", there is more to consider than just technology. Let oneHOWTO explain.

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Steps to follow:

How do fitness trackers work?

Activity trackers or fitness bands work via sensors fitted into a bracelet or watch. This straps on to the wrist and the sensors pick up your vital statistics. The sensors then send this information to a smartphone or device for it to be logged and charted against the rest of your information. They can be worn throughout the day, remaining active 24/7. Their role is specifically to count and quantify all your physical activity. In doing so, you should be able to motivate yourself better to exercise and ensure you are doing what you need to keep up your fitness.

There are different types of sensors, not all of which are on every fitness tracker:

  • Accelerometer: the name of this fitness tracking component sort of gives it away. An accelerometer tracks the proper acceleration of a given body (in this case it is a human body). This means the acceleration is relative to gravity and the accelerometer tracks information bit horizontally and vertically. More advanced accelerometers, the kind more commonly used now, have a 3 axis accelerometer with a gyroscope incorporated into it. This means it can manage both distance and orientation.
  • Altimeter: this is similar to an accelerometer, but is used to gauge altitude. This is particularly good if you are a hiker or mountain climber as it can gauge how far you've gone while taking into consideration inclines and declines.
  • GPS: GPS stands for Global Positioning System and that is exactly what it does. It locates your position anywhere in the world. It does so by sending information up to satellites orbiting the earth and bounces them off to work out your location. This is a more complicated sensor and because of this, is best to have if you really want to map your progress. However, this also means they drain power more than non-GPS fitness trackers.
  • Galvine skin response: this sensor works via electrodes on the skin and can tell when you start to sweat. This is useful because sweating indicates increased physical activity, even if you are not partaking in exercise. The electrodes monitor your electrical conductivity and therefore your physiological state. Some claim this can also help with your psychological state as you can increase electrical conductivity while stressed. However, actually monitoring accurately your psychological state is beyond the technology available.
  • Light sesnsors: there are two main types of light sensor on fitness trackers. The first is a UV sensor which can tell us if we have been in the sun too long. The other is an ambient light sensor. This tells the activity tracker what time of day it is and helps to record the exact time of day.
  • Heart monitor: this is where things get a little trickier in terms of accuracy. Most heart monitors on activity bands will use a light to shine on capillaries which record your heart rate with limited guarantee of accuracy. A bioimpedance sensor can more accurately measure your heart rate as well as breathing level and galvanic skin response, but not all activity trackers will have one.
How do Activity Trackers Work? - Step 1

Once these vital statistics are recorded by the sensor, the information is sent via bluetooth to a smart device, usually a smartphone. The corresponding mobile app is usually installed with the fitness tracker you buy. It will take the information and chart your activity. This will include how far you have moved, how many calories you burned and other aspects of your physical activity.

You have to calibrate the device using the app first. You do this by inputting your vital statistics which include height, weight, blood pressure, etc. This will calculate the right level of workout you should be looking for and help you to reach this goal. However, different devices use different algorithms to calculate these statistics for you. This means that they have varying levels of accuracy. The integrated software of your activity tracker should be a big consideration when purchasing one. Some of them are no more than a glorified pedometer (step counter).

Even if you do not have the best corresponding app for your activity tracker, it is not a complete waste of time. None of the recording of your physical exercise routine will be perfectly accurate, but it can still give you a good idea and an all round better perspective on your health and fitness. This in turn can help encourage you to keep going.


Furthermore, activity bracelets allow you to set your own goals to achieve so that you can improve your fitness. Whether you want to spend more time exercising to stay fit or whether you want to lose weight, you just enter your goals and once you've completed them the bracelet will alert you via a light or vibration signal.

Unfortunately, this is where the downside of activity trackers fits in. The Atlantic ran a story in 2016 called "Not All Who Wear Fitness Trackers Are Lost". This article discussed the then recent findings of the Journal of the American Medical Association which ran a study to see if activity trackers assisted in weight loss. 471 people were included in the medical trial, half with devices to track steps and calories burned, the other half without. The results were possibly surprising. Those without the activity tracker lost an average of 5 pounds more than those using the fitness bands.

The culprit, argues writer James Hamblin, is something called a health halo. This is where the wearer of the device believes they are being more healthy just by wearing it than in actuality. The psychological damage appears to be in the fact that many with these activity trackers get a placebo affect from wearing them and get complacent. This means they often don't actually do enough of the corresponding exercise. Counting calories on its own also doesn't necessarily help you lose weight as the real life application can vary.

Essentially, these devices can replace the intuition which we naturally have in regards to our bodies. We think that we are doing well because of what is displayed on the screen of our activity trackers, even if our bodies are not saying the same thing. For those in the 2016 study who did not wear the fitness trackers, they used intuition and pushed their bodies according to how they felt, not according to what the device tells them.

How do Activity Trackers Work? - Step 3

Many models of activity bracelet also record your sleep cycle and what you eat every day. They measure nocturnal activity and show you the resulting information, such as the hours you spend in bed, when you wake up during the night and your different sleep phases. These sleep phases are very important and it is not simply an issue of quantity, but also of quality. The activity tracker can help you track your sleep and see what lifestyle changes you may need to make to improve your health, It is important to sleep well, especially if you wan to avoid the consequences of little sleep. You can also set an alarm to wake you up in the morning with a slight vibration on your wrist which won't annoy others.

Fitness bands or activity trackers can be very useful tools if what you want is to set specific but flexible goals to get fit. You can trace and modify them through the apps to check and encourage progress. However, if you don't have the right approach you might not be very successful in your fitness endeavor. The right approach is to see the activity tracker as a fitness aid, one which can help encourage you. It is not a personal trainer nor a magic device which will make you lose weight. If they do invent one of those, we'll be the first to let you know.

If you want to read similar articles to How do Activity Trackers Work?, we recommend you visit our Fitness category.

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