Conventional pedometers count steps by detecting movement. Some also calculate calories and distance based on your weight and a stride length that you program in at the beginning of the workout. GPS models are more expensive—$200 to $300—and measure distance outdoors using satellite information. (Garmin and Nike sell shoe pods to use when the satellite can’t be accessed because you’re indoors or somewhere heavily wooded, but we didn’t test them.) Because GPS watches track distance, not steps, they can also be used for biking and, in some cases, swimming, though we didn’t test those uses. The phone apps measure steps by sensing body motion. They may take more trial and error to use, but also cost the least; all were $4 or less.
To test the conventional pedometers and apps, staff volunteers clipped each device to their waistband or belt while walking on a treadmill at various speeds, climbing and descending stairs, and walking outside. (For the apps, the phone was clipped to a belt with a cell-phone holder or carried in a pocket.) We compared the pedometer step counts to the testers’ own counts. For GPS watches, volunteers ran 1 mile outside on level terrain and another 0.8 mile downhill. We measured accuracy against a professional distance-measuring wheel. Sensory panelists also evaluated each device on how easy it was to use.
