Pedometers enable anyone interested in improving personal fitness to inexpensively set goals, monitor progress, and incorporate exercise into the daily routine. These simple devices count steps taken and calculate distance traveled based on the length of stride. Today's average American takes about 5,500 steps daily --- about enough to travel 2 1/2 miles, according to the University of Nevada Cooperative Extension. For good fitness, walkers need to nearly double that.
Mileage Accuracy
Pedometers only estimate distance traveled. Setting a pedometer properly involves adjusting the device to record your average length of stride. Pour some water on a level sidewalk to make a small puddle. Walk away a few steps and then walk briskly through the water, making sure to get both shoes wet. Turn about and measure the distance from heel print to heel print. Set the stride length on the pedometer to match, and the pedometer counts each step as that much distance traveled. If the step you actually take varies, real distance won't match the pedometer reading. Most pedometers measure distance within a 10 percent margin of error.
Pedometer Types
Pedometers count steps when an internal sensor reacts to movement. Cheap pedometers sense the bounce of a footstep with a weighted hair-spring. Mid-priced pedometers use stronger coil springs. Both types work reliably when worn level and near the hip. If positioned incorrectly, these pedometers miscount steps. More expensive pedometers with electronic movement sensors work in any position and offer much better counting accuracy. GPS pedometers calculate position through the Global Positioning System satellite network. This type of pedometer accurately calculates speed and distance but won't record the number of steps taken.
Considerations
Even the cheapest pedometers offer the essentials needed for a basic fitness walking program. Walkers test any step-counting pedometer's counting accuracy by resetting the counter to zero and then counting steps mentally as they walk. After 50 steps, the pedometer should read 50. If the pedometer miscounts, adjust the position on belt or clothing until the device counts properly. Keeping a journal of walks and distance helps judge mileage accuracy. Walking faster usually results in a longer stride, so a faster-than-normal walk can cause the pedometer to underestimate distance.
Durability
Aging pedometers grow less and less accurate. The cheapest hair-spring pedometers may fail in six months, while coil-spring pedometers should stay accurate for about two years. Electronic movement-sensor pedometers last longest of all. Lifetimes of individual units do vary, so after a couple of years, owners should check their pedometer's accuracy and replace it if needed.
GPS Options
Although very accurate in perfect conditions, GPS pedometers depend upon a clear view of the network satellites. This type of pedometer won't work inside buildings and may lose track of the GPS net outside as well. GPS pedometers need a line-of-sight connection to at least three satellites to calculate position and speed. Adding a fourth satellite signal greatly improves the resolution. Buildings, trees, weather and even the placement of the unit on the person all affect the accuracy of the device.
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