From Tommy Thompson to Ronald McDonald™, everyone seems to be step counting these days. But what separates the tools from the trinkets? Let's look inside popular pedometers and find out.  
Features draw your attention and inflate the price of the pedometer, but are they worth it?








     
Steps

All step-counters count steps to a certain degree of accuracy. Certain things can be extrapolated from this number if the user inputs things like stride length and weight. These calculations are only as accurate as the step count and the regressions used.

Distance

This is merely a calculation done by multiplying the number of steps times your average stride length. The accuracy of this calculation depends not only on the determination of your own stride, but the pace of your walking. Generally, the faster one walks, the longer his stride becomes, so walking faster than normal will cause underestimations of the total distance walked and slower walking will cause an overestimation.

Calorie Expenditure

Most pedometers that show caloric expenditure show gross caloric expenditure, which are the calories expended by the movement performed plus your metabolic rate. This number is somewhat inflated, for those using pedometers to measure activity-related calories that add their personal BMR to that number are in effect, double-counting their BMR for the period of activity.

The NL-2000 activity monitor by NEW-LIFESTYLES, Inc. is the only current available model to report net and gross caloric expenditure, taking into account the intensity of the steps and the calories burned by the body at rest. It uses the owner's height, weight, gender, and age to calculate the Basal Metabolic Rate of the individual. Other pedometers that report calorie consumption require only the weight of the user, and like a treadmill, are estimations using standard regressions. Pedometers by nature can not know whether an individual is going up or down hill or carrying a backpack or other load that affects the person's caloric output. Examples of these pedometers include the Yamax SW-701, Walk For Life LS 2525, Omron HJ-112, Oregon Scientific PE316CA, Freestyle Pacer Pro, Bodytronics Pro Cal, Freestyle Tracer, and the Sportline 343. Though most do not specificy which is being given, it can generally be assumed that gross calories are being displayed.

Generally, the caloric expenditure feature is a poor motivator with a large margin of error depending on the activity performed. This number can be very helpful for those on a strict weight control program, but current research shows many pedometers underestimate caloric expenditure by a factor between 5-10%. Remember, pedometers can count steps with great accuracy, but again have limitations extrapolating other measurements.

Exercise Timer

An exercise timer currently only found on several pedometers including the Walk For Life LS2525, Accusplit 1590, and the Freestyle Pacer Pro. The timer increments the moment the pedometer detects a step, but It does not delineate between walking, running, or skipping to the refrigerator. Many instructions suggest that the timer is to be used to time specific activities, but the feature is marketed as a way to judge whether one has met the CDC's recommendation of 30 minutes of moderate to vigorous exercise. One can use the timer to time a walk or a jog automatically, but this requires resetting the pedometer and losing one's daily step total accumulated to that point. The Pacer Pro uses a 'Lap' system, which shows overall movement time and the most recent bout of movement as well, which makes the feature much more useful. Using the timer to track daily activity time yields disappointing results, due to the devices' lack of discretion between random motion and purposeful walking. Even rather sedentary days will display upwards of two hours on the timer, which can be highly misleading.

Others

Other features found on pedometers include radios, talking pedometers, panic alarms, heart rate monitors, and backlit displays. These added components add weight, decrease the battery life, and inflate the cost of the pedometer. The extra features generally decrease the accuracy of the device.


JSC Engineering LLC is an Electrical Engineering Consultant Group specializing in product design & performance testing.

© 2008 JSC Engineering, LLC. Direct reprint requests to webmaster@pedometers.com.