Accuracy of a piezoelectric pedometer in persons with and without Down syndrome. (December 2016) - Agiovlasitis, Stamatis
Highlights: A tri-axial piezoelectric pedometer records steps accurately in persons with DS. Accuracy is high at the preferred walking speed and at speeds ≥1.0 m s −1 . Pedometer accuracy is compromised at slower speeds. Across speeds, pedometer accuracy does differ between persons with and without DS. Pedometers effectively assess ambulatory activity in persons with and without DS. Abstract: Background: Piezoelectric pedometers with a tri-axial accelerometer mechanism may effectively monitor physical activity in persons with Down syndrome (DS), but their accuracy has not been determined in this population. Aim: To examine the accuracy of a pedometer with a tri-axial accelerometer mechanism in measuring steps at different walking speeds in persons with and without DS. Methods: Eighteen persons with DS (8 women; age 25 ± 7 y) and 22 persons without DS (9 women; 26 ± 5 y) participated in this study. Participants completed six over-ground walking trials at the preferred speed and at 0.5, 0.75, 1.0, 1.25, and 1.5 m s −1, each lasting 6 min. The steps taken were measured with hand-tally and with the Walk4Life MVPa piezoelectric pedometer. Pedometer accuracy was assessed with absolute percent error and Bland-Altman plots. Results: Absolute percent error did not differ between persons with and without DS across speeds. Error decreased with increased speed (p < 0.001), but leveled off at ≥1.0 m s −1 . Pedometers underestimated steps at 0.5 and 0.75 m s −1, but were highly accurate at the preferred walking speed and at speeds ≥1.0 m s −1 . Conclusions: A piezoelectric pedometer with a tri-axial accelerometer mechanism measures steps with high accuracy at the preferred walking speed and at speeds ≥1.0 m s −1 in persons with and without DS. Accuracy, however, is compromised at slower speeds. Across speeds, pedometer error is similar between persons with and without DS.