Comparison Of Two Waist-mounted And Two Anklemounted Electronic Pedometers

Abstract

PURPOSE The purpose of this study was to compare two ankle-mounted pedometers (Step Watch 3 [SW-3] and Activity Monitoring Pod 331 [AMP]) and two waist-mounted pedometers (New Lifestyles NL-2000 [NL] and Digiwalker SW-701 [DW-701]) under controlled and free-living conditions. METHODS In part I, 10 males and 10 females walked on a motor driven treadmill at various speeds (27, 40, 54, 67, 80, and 107 m·min−1). An investigator determined the actual steps with a hand counter. In part II, participants performed leg swinging, heel tapping, stationary cycling, and car driving (6.4 km on city streets). In part III, a subset of 15 participants volunteered to wear all four pedometers for a 24-hr period. RESULTS The SW-3 displayed values that were within 1% of actual steps during treadmill walking at all speeds. The other devices underestimated steps at slow speeds but all gave mean values that were within ± 3% of actual steps at 80 m·min−1 and above. The SW-3 registered some steps during heel tapping, leg swinging, and cycling, while the AMP was only responsive to leg swinging. During car driving none of the devices recorded more than 8 steps, on average. Compared to the SW-3, over 24 hours the AMP and DW-701 recorded 18% and 15% fewer steps, respectively (P <0.05), while the NL recorded 11% less (NSD). CONCLUSIONS The SW-3 has superior validity during slow treadmill walking (<67 m·min−1). Although it is more likely to detect certain types of non-ambulatory activities, this is probably not a major source of error. Over 24 hours, the SW-3 gave higher estimates of steps day−1 versus the DW-701 and AMP. This suggests that the SW-3 could be a useful criterion for validating other pedometers during 24-hr free-living activity.