A Lab-based Test To Evaluate Pedometer Longevity

Abstract

Purpose Numerous studies have evaluated the step counting accuracy of commercially available pedometers. The longevity of pedometers (maintenance of step counting accuracy with repeated use), however, has yet to be determined or reported in the literature. The purpose of the present study was to test the efficacy of a lab-based protocol for measuring pedometer longevity using three commercial pedometer brands. Methods 3 brands of new pedometers (n = 10 each) were tested: 1) Digi-Walker (DW701; Model SW-701); 2) Sportline Electronic Pedometer (SL345; Model 345); 3) McDonald=s Stepometer (MCST). To simulate habitual use of the pedometers during walking activities, each brand of pedometer was mounted to a modified benchtop orbital shaker. The shaker oscillated at 2.5 Hz which corresponded to one step accumulation on a pedometer per cycle and approximated a 80.4 m/s (3.0 MPH) walking speed when compared to the output from an Actical activity monitor (Mini Mitter, Inc.). Prior to testing on the shaker, the accuracy of each pedometer was verified using a treadmill walking test. Pedometers were worn (one at a time) by a lab technician while walking on a treadmill at 80.4 m/s for exactly 50 steps on 3 successive trials. Actual step count for each trial (50 steps) was verified using a hand tally while the pedometer step count was recorded and reset to zero between trials. A pedometer was considered to have “failed” the treadmill test if the average pedometer step count (over the 3 trials) differed from the actual step count by ±5 steps. Non-failed pedometers were then mounted to the shaker and set (using an automated timer) to accumulate approximately 100,000 steps before retesting on the treadmill for step counting accuracy. The average number of steps accumulated prior to failing the treadmill test was recorded for each pedometer. Each pedometer was tested until failure or until a high accumulation of steps without failure (ie. 2–2.5 million). Differences between the 3 brands were evaluated using a 1-factor ANOVA at the 0.05 alpha level. Results The DW701 accumulated significantly more steps (Mean±SE: 2.38±0.03 million steps) than either the SL345 (0.71±0.06 million steps) or the MCST (0.25±0.03 million steps). All of the SL345 and MCST pedometers were tested until failure while testing the DW701 pedometers were stopped due to high step counts without failure. Conclusions The lab-test of pedometer longevity provided a clear stratification between the three pedometer brands tested. This type of test may be useful to perform prior to using any pedometer brand for large-scale physical activity tracking or intervention studies.