Pedometers are small devices that can be placed on the waist to track the number of steps you take. Originally invented by Leonardo da Vinci for map building and measuring the distance walked by Roman soldiers, they have evolved over time into very sophisticated devices that now not only track steps, but distance, calories burned and time walked. Even portable music devices and cell phones have them built in. With so many models on the market, it can be confusing trying to figure out what one is the most reliable.
Types
There are two primary types of pedometers. The first type is made up of a spring-suspended lever that moves up and down in response to the vertical motion of the hip. The lever opens and closes an electric circuit, which counts the number of steps taken. The second type distinguishes ambulatory activities through a strain gauge.
Features
Pedometers were designed to count steps, which is what they are most accurate at performing. Some estimate distance and calories burned, but unfortunately most are not very accurate at either one of these added tasks. In order to increase the accuracy of the distance walked, your pedometer must have a way for you to measure and then input your average stride length. As for calories burned, the device must also have a way for you to input your body weight, because caloric expenditure depends on your body weight. Both of these features also then rely back on the accuracy of the number of steps taken.
Step Accuracy
A 2003 study reported in "Medicine and Science in Sports and Exercise" found the Kenz Lifecorder, New Lifestyles NL-2000, and Yamax Digiwalkers SW-200 and SW-70 to be the most accurate. The drawback is they also tend to be more costly. Other studies reported in the article found that accelerometer-type pedometers tend to be more accurate than the lever arm models, but the drawback is that they also tend to be more expensive and have a much shorter battery life. These studies found that the suspended-lever pedometers underestimate the actual number of steps taken.
Wearing Position
One of the first things anyone who uses a pedometer should do is make sure its being worn properly. The pedometer should be placed on your belt or waist band. It should be above the hip bone and in line with the knee. If it's placed too far in front or to the side, it will not count accurately. Lever arm models are also sensitive to the angle at which they are placed on the waist. You should be sure that this type is placed in an upright, level position.
Testing Your Pedometer
If you already have a pedometer and you want to check and see just how accurate it is, the American College of Sports Medicine recommends doing your own 20-step test. This is easy to perform; you simply take 20 steps at your normal walking pace. According to ACSM, if your pedometer reads between 18 and 22 steps, you can consider it fairly accurate. If it doesn't, then try to reposition it and test again. If it continually fails, you should consider a different type of pedometer.
Influences
There are many things that can affect the accuracy of your pedometer. Most models tend to inaccurately report the number of steps at slower walking speeds. ACSM notes that most are fairly accurate if you are walking at least 2.5 mph. Abdominal size and loose waist bands also affect the counting.
10,000 Steps a Day
The overall purpose of pedometers is to track the number of steps you are taking. Healthy adults should aim for 10,000 to 12,500 steps per day to be considered active. If you are continually falling below that number you need to find ways throughout your day to add more steps. These can include taking the stairs, walking to work or parking a little further away from your destination.
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