How Pedometers Work
Pedometers are an excellent way to gauge basic activity level and to keep motivated. The gold-standard goal is 10,000 steps a day, which equals 5 miles.
"The whole idea of a pedometer is to see how many steps you've taken," says David K. Spierer, assistant professor of sports sciences at Long Island University's Brooklyn Campus.
Basic Pedometers
Older pedometers, such as the freebies given out at health fairs, use a ball device inside. Each time the ball moves up and down, the counter adds a step, theoretically adding up the number of times a person's hips move up and down as they walk.
These pedometers need to be clipped on at the hip near the pelvic bone to work most accurately. "The problem with balls is they are not precise. If I get up from a chair it will tell me I took steps," Spierer says.
Using Sensors and Sattelites
Newer, more sophisticated pedometers use a sensor to measure hip movement and are more accurate. Many of these pedometers also will give distance readings and calorie counts. They require users to measure stride length and input that information into the device.
The newest technology utilizes a GPS system in which a satellite is able to relay information on distance traveled as well as speed. However, for obvious reasons, these are not good for indoors, Spierer says.
Pedometers that give calorie counts are really giving estimates of calories burned, calculated with the Harris-Benedict Equation.
Accelerometers
For a more accurate gauge of distance and calories burned, you can use a device called an accelerometer, sometimes called a "piezoelectric pedometer." In these devices, a sensor takes various measurements, such as how fast you are moving. It then calculates the distance you've traveled and estimates how many calories you've burned.
Other Devices
Other devices, such as the Polar foot pod running speed sensor, serve a similar purpose by providing speed and distance readings, but are not classified as pedometers.
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