Question:

Which is more accurate for calculating miles or steps walked, a pedometer or a treadmill?

Answer:

If you’re more interested in knowing how far you walked, the treadmill wins hands down, says John Porcari, Ph.D., program director of the Clinical Exercise Physiology program at the University of Wisconsin, La Crosse. A computer inside the treadmill measures how far you walked based on your speed and time and the rotation of the belt under your feet.

If you want to know how many steps you’re taking, a treadmill won’t help. “I’ve never seen a treadmill that offers that data,” says Porcari. Instead, clip on a pedometer. These devices work in various ways, depending on the model, but most of them contain a small mechanical device or a pendulum inside that oscillates with every step you take. All you need to do is set your stride length so that the pedometer knows when to add a step. (Most come with easy instructions for setting the stride length.)

One caveat: All pedometers are not created equal, says Porcari. “The cheapest ones, those that may come free with a small purchase — I’d say those are only 30 to 50 percent accurate” he says. “More expensive ones, which are still reasonably priced at less than $50, offer 70 to 90 percent accuracy.”

As for the question of which is more important, steps or miles, both are good ways to track how much activity you’re getting. But if you’re trying to hit the surgeon general’s recommendation of 30 minutes of exercise a day, the most reliable way to check yourself is with a good, old-fashioned watch. Spend 30 minutes on the treadmill or take three 10-minute walks a day with your pedometer to rack up the miles, the steps, and the minutes.

Liz Krieger
Senior Editor