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How Does BodyMedia FIT Count Calories?

Everything starts with the multi-sensor Armband from BodyMedia.The Armband takes a broad 24/7 view of your life by "reading" your body from five different perspectives.

1. The armband contains an "accelerometer", a device that we use to measure many aspects of motion. Your car air-bag system uses an accelerometer to know when you have been in an accident and deploy the air-bag, your Nintendo Wii game controller contains an accelerometer to measure how you move the controller to play the games.
   
   
2. We counts your steps, using the distinctive walking and running motions measured by the accelerometer.
   
   
3. We measure your "Galvanic Skin Response". The two stainless steel pads on the back of your armband are the GSR sensor that determine how much you are sweating.
   
   
4. We measure your skin temperature using an electronic thermometer inside the armband.
   
   
5. We measure the rate at which heat is being dissipated from your body, this is your "heat flux". Exercise physiologists are interested in the heat energy produced by the body, your muscles are fairly inefficient and we all produce a lot of heat energy when we perform physical work.

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How Does the BodyMedia FIT Determine Your Activity?

The characteristic signals from the sensors allow us to determine what type of activity you are doing. This is important because the human body burns calories differently depending on the activity.

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Crunching the Numbers

When your armband data gets to the web site, the signals from the different sensors are analyzed by the algorithms. The algorithms know how to match sensor values to calorie burn. There are different algorithms for different activities. For example, the "running algorithm" knows how the motion and temperature sensors relate to calorie burn specifically while people are running. The "resting algorithm" knows how to match a different set of sensors and their relationship to calorie burn for people who are resting. If you have a BodyMedia Display you will have seen up to the minute calorie values displayed. The armband contains a miniaturized set of algorithms that can calculate calories and send them directly to the display every minute.

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Calorie Burn

The calorie burn is displayed and stored in the BodyMedia FIT Activity Manager. The diverse physiological parameters recorded in the Armband give a comprehensive picture of what your body is doing and its level of exertion. This leads to a more accurate estimation of calories burned under the varying circumstances and situations that you find yourself in every day.

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How Does BodyMedia FIT Count Steps?

Walking	Running

The characteristic signals from the accelerometer motion sensors allow us to identify both natural walking and running. An algorithm in the armband looks for these characteristic signals and records the step count per minute.

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