Background:The last decade's technological advances have spurred a continuously increasing interest in objective monitoring of physical activity with the use of wearable devices. Even though an increased accuracy is important in some lines of research, a balance between precision, feasibility and low-cost monitoring technologies is clearly needed.Aims: The purpose of this study was to compare the accuracy for step counting between one springlevered pedometer, two piezo-electric pedometers and two free of charge pedometer applications for Android smartphones, under free-living conditions.Methods: Eleven healthy adults, ranging in BMI from 20.20 to 24.77 kg*m (2 , volunteered to participate in the study. They wore the selected criterion pedometer Yamax SW-200 (SW), which is considered the ''gold standard'', the Garmin Vivofit (GV), Medisana ViFit (MV), Accupedo application (AC) and Pedometer 2.0 application (PD), for a 24-h period, under free-living settings. Data were analyzed using descriptive and inferential statistics.Results: All devices and applications demonstrated strong correlations with the SW reference pedometer (IC 0 0.86 Á 0.94), but often large mean differences Significant differences were observed among the five pedometers (F 0 5.21, p 0 0.01). Only the PD counted almost similar steps as the SW (F 0 0.57, p 0 0.47), even though it had high Mean Absolute Percent Error (MAPE). The 3 remaining pedometers significantly overestimated counted steps, with the AC application been the least accurate [F 0 11.92, p B 0.01; MAPE 0 36.15%].
Conclusions:The results of the present study showed favorable outcomes for the estimation of steps per day for the PD application in healthy and normal weight people. The two piezo-electric pedometers (GV -MV) appeared to give similar values, however these values constantly overestimated step counting compared with the criterion pedometer. Taking into account the free cost and feasibility of the PD application, the results demonstrate good potential for future use in free-living settings.