Precision and accuracy of an ankle-worn accelerometer-based pedometer in step counting and energy expenditure

Randal C. Foster, Lorraine M. Lanningham-Foster, Chinmay Manohar, Shelly K. McCrady, Lana J. Nysse, Kenton R. Kaufman, Denny J. Padgett, James A. Levine

Research output: Contribution to journalArticlepeer-review

146 Scopus citations


Background. Walking is a widely used approach to increase physical activity levels in obese patients. In this paper, we investigate the precision and accuracy of an ankle-worn dual-axis accelerometer (Stepwatch) and investigate its potential application as a predictor of energy expenditure. Methods. Twenty healthy subjects (10 lean, 10 obese) wore spring-levered (Accusplit), piezoelectric (Omron HF-100), and Stepwatch pedometers. Subjects walked on a treadmill at 1, 2, and 3 mph and in a hallway at 1 and 1.85 mph, during which energy expenditure was measured. Results. The Stepwatch counted 99.7 ± 0.67% (mean ± SEM) of the manual counts. In comparison, the Omron pedometer counted 61 ± 3.3% and the Accusplit counted 26 ± 2.8% of the manual counts at 1 mph although all pedometers were accurate (>98% of counts) at 3 mph. In repeated measures, the Stepwatch produced negligible variance (SD = 0.36) over all speed whereas the other pedometers showed a large amount of variance at all speed (SD = 4-13). Stepwatch counts were predictive of walking energy expenditure corrected by weight (r2 > 0.8). Conclusion. The counts from the Stepwatch were virtually identical to the manual counts from a trained investigator and provided a reliable predictor of walking energy expenditure.

Original languageEnglish (US)
Pages (from-to)778-783
Number of pages6
JournalPreventive Medicine
Issue number3-4
StatePublished - Sep 2005


  • Ambulation
  • Obesity
  • Physical activity

ASJC Scopus subject areas

  • Epidemiology
  • Public Health, Environmental and Occupational Health


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