What are they?
A pedometer is a device about the size of a beeper that you clip to your waistband and it counts the number of steps that you take.
Are They Accurate?
Pedometers detect the vertical motion of your hips as you walk. A pedometer is most accurate, studies show, when the person is walking faster than 3 mph. As the speed slows so does the accuracy and this is due to the mechanics of walking at a slower speed. People tend to drag or shuffle their feet at slower speeds and these results in less vertical motion of the hips that the pedometer needs to count steps. Accuracy at or above 3 mph can exceed 96% and at 2-3 mph can fall to 74%. Below 2 mph the accuracy can be as low as 60%. Needless to say that a brisk walk is what is needed here.
How Do Pedometers Work?
There are 2 types of pedometers in terms of internal workings. The first type is a mechanical spring lever that has a horizontal bar that is suspended by a spring parallel to the ground. When you walk and induce a vertical force or motion into the bar it moves upwards to complete an electrical circuit. Each closing and opening of the circuit is counted as one step.
The second type is also a beam but with a weight on the free end. At the other end the beam is connected to a piezoelectric cell. When vertical motion is applied, a pressure is induced into the cell that produces a voltage that is proportional to the force applied. These voltage oscillations are used to count you steps.
Which Type Is Best?
Piezoelectric type pedometers are more sensitive at slower speeds and tend to be more accurate below 2 mph. They also are not as sensitive to being tipped over from their horizontal position like a spring lever type is. A piezo type pedometer may only see a 10% reduction in accuracy when tipped at speeds below 2 mph while a spring lever could see a reduction in accuracy of up to 60% below 2 mph. So, if you are older or overweight and walk slowly, the piezo design is probably the way to go.
Pedometers should be worn on your waistline in line with your leg. If you have a problem with attaching to your waistline then you can attach to your sock. This should give you the same vertical motion needed.
Testing Your Pedometer For Accuracy
When you first get your new pedometer and want to check it for accuracy or want to do interim checks on one you own now then set the pedometer to zero. Carefully count off 100 steps to see what kind of result you get. Remember that you are looking for a +/- 10% accuracy, which means anything in the range of 90-110 steps. If you do not get it in this range then try to reposition your pedometer and walk again and see if that makes a difference. Some people have different gaits to their walk and it is just a matter of trial and error to find the best position for you.