Cheap Inaccurate Pedometers Could Hurt Fitness Efforts

Yamax CW-701 Pedometer
Yamax CW-701 Pedometer. Courtesy of Pricegrabber

Wearing a pedometer can spur people to add more steps to their day and get in more exercise. However, a study suggests that using cheap, inaccurate pedometers could do more harm than good in giving people an inaccurate count or dissuading them from using a more accurate pedometer.

Cheap Pedometers vs. Yamax Digiwalker

The study tested a cheap Stepping Meter vs. the accurate Yamax Digiwalker SW-200 on 35 study subjects.

Each subject wore 1 Yamax pedometer and 5 Stepping Meters all day and the step counts were recorded at the end of the day. Each subject tested 30 pedometers over the course of six days.

Cheap Pedometers Overcounted Steps

A 10% variation in the step count vs. the Yamax pedometer was considered acceptable. Only a quarter of the Stepping Meters met this mark, while 74% overcounted or undercounted. Of the ones that were inaccurate, most of them overcounted the steps - with a third of them overcounting them by 50% The others undercounted steps. People who think they are walking 10,000 steps per day may only be walking 5,000 steps per day.

Checking Your Pedometer Accuracy

The simplest test of whether your pedometer is accurate is to count 100 steps as you take them (each foot counts as one step) and to compare that with what the pedometer says. You can see whether your pedometer counts jiggles as steps by noting the step count before sitting for awhile and going through your daily motions, and compare it to the count after a half hour or hour of sitting.

What Makes a Pedometer Inaccurate

Inexpensive pedometers usually have a hairspring mechanism calibrated at the factory. If they are too sensitive to motion, they overcount steps. Too insensitive and they undercount steps. Hairsprings also tend to change their calibration over time and overcount steps as they age.

The Yamax pedometers use a coiled spring mechanism and better quality control at the factory in calibrating the pedometers. The coiled springs stay calibrated ten times longer than the hairsprings.

Why Worry About Pedometer Accuracy?

The study authors concluded, "The use of inexpensive pedometers should not be recommended because of considerable validity problems, which may damage any investment in good quality pedometers for physical activity health promotion."

  • False Readings: If you set an absolute goal, such as 10,000 steps per day, using a pedometer that overcounts steps could give you a false sense of security in reaching that goal.
  • Set an Increase Goal Instead: First see how many steps you usually walk per day, then aim to increase that by 2000 steps. If you are using a cheap pedometer, you may want to increase it by 2500 or 3000 steps per day if you believe your pedometer is overcounting steps. Continue to increase your goal by 2000 steps until you reach 10,000 - 15,000 steps per day.
  • Pedometer Disgust: If you use a cheap pedometer and see wide variations in how it counts, you might think all pedometers are as bad. This is not true. It is worth the investment to buy an accurate pedometer such as the Yamax Digiwalkers or one of the piezo-electric accelerometers, which are highly accurate for step counts.

Most Accurate Pedometers

A previous study concluded these pedometers recorded steps with 99% accuracy:

Sources:

K De Cocker, G Cardon, I De Bourdeaudhuij, "Validity of the Inexpensive Stepping Meter in Counting Steps in Free Living Conditions: a Pilot Study." (.pdf file) British Journal of Sports Medicine, 2006;000:1–3. doi: 10.1136/bjsm.2005.025296

Crouter, Schneider, and Bassett, "Spring-Levered versus Piezo-Electric Pedometer Accuracy in Overweight and Obese Adults." Medicine & Science in Sports & Exercise. 37(10):1673-1679, October 2005.

Crouter, Schneider, Karabulut and Bassett, "Validity of 10 Electronic Pedometers for Measuring Steps, Distance, and Energy Cost." Medicine and Science in Sports and Exercise, 35 (10), 1779–1784. August, 2003.

Crouter, Schneider, Karabulut and Bassett, "Pedometer Measures of Free-Living Physical Activity: Comparison of 13 Models." Medicine & Science in Sports & Exercise. 36(2):331-335, February 2004.

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