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Pedometer Mechanisms - What Makes Your Pedometer Tick?

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Updated May 14, 2014

Omron HJ-321 Pedometer 1800

Omron HJ-321 Pedometer

Wendy Bumgardner ©

Pedometers are quite different under the hood. The mechanisms used to count steps vary in ways that affect noise, accuracy, and longevity of the pedometer.

Accelerometers - Piezo-electric Pedometers - The Quiet Ones

This pedometer mechanism is quiet - it has no moving parts, so there is no annoying click with each step. It also tests as more accurate than spring-levered mechanisms, especially when walking at slower speeds and when the pedometer is tilted at an angle as it might be with those with various body shapes. The pedometer uses a strain gauge, which measures how fast you are moving (inertia). This uses more battery juice, so users need to replace the batteries more often then with some other pedometers - every 6 months or so.
Advantages
  • Silent
  • More accurate for those with protruding waists, or if worn at various angles.
  • More accurate at slower walking speeds
Disadvantages
  • Must replace battery more often.
Models

Spring-Levered Pedometers with Coiled Spring

A spring-levered pedometer mechanism moves with each step, the lever arm swinging downward and closing a contact to count a step, then the spring returning it to its original position. A coiled spring has a much longer lifespan and retains its accuracy more than a hairspring. Researchers have used the Yamax Digiwalker with the coiled spring mechanism as a gold-standard for accuracy.
Advantages
  • Accurate
  • Longer battery life
Disadvantages
  • Clicks
  • Not as accurate as the piezoelectric pedometers when tilted. Those with rounded stomachs may not get as accurate of a reading.
Models
  • Yamax Digiwalker 701 Review | Compare Prices
  • Yamax Digiwalker 200 Review | Compare Prices

Spring-Levered Pedometers with a Hairspring

A hairspring will lose its accuracy much faster than a coiled spring. After about a million steps, the spring is weakened and it begins overcounting steps. A coiled spring retains its accuracy for over ten times longer. Most of the pedometers on the market use a hairspring rather than a coiled spring.

What Makes a Pedometer Click so Loud?

The clicking noise in a spring-levered pedometer comes from the closing of the contacts.
Magnetic Switch: Some pedometers use a magnetic switch to close the contact - it clicks, but there is no actual contact being made.
Metal Contacts: For those pedometers in which metal contacts metal, a pedometer can be made quieter by covering the contacts in rubber - which also lengthens the lifespan of the contacts. The Yamax Digiwalker models coat their contacts in rubber, making them quieter than most. Cheaper pedometers don't bother. A noisier metal contact pedometer is likely to have a shorter lifespan than a quieter pedometer.

How Long Will the Pedometer Last?

A Montana State University study by Dan Heil found that the hairspring pedometers would probably be accurate for only 18 months of use, under 1 million steps. The coiled spring mechanism in the Yamax Digiwalker was still going strong and accurate for many millions of steps, with an estimated lifespan of 4.5 years. Be sure to keep the battery-replacement instructions handy, or bookmark the company's web site for instructions.

References
"Spring-Levered versus Piezo-Electric Pedometer Accuracy in Overweight and Obese Adults," Crouter, Schneider, and Bassett, Medicine & Science in Sports & Exercise. 37(10):1673-1679, October 2005.
"Validity of 10 Electronic Pedometers for Measuring Steps, Distance, and Energy Cost" Crouter, Schneider, Karabulut and Bassett. Medicine and Science in Sports and Exercise, 35 (10), 1779–1784.
Montana State University Pedometer Longevity Study

Updated 2/7/06

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