Validity of the SenseWear armband step count measure during controlled and free-living conditions

Abstract

Background/objective: Advances in technology continue to provide numerous options for physical activity assessment. These advances necessitate evaluation of the validity of newly developed activity monitors being used in clinical and research settings. The purpose of this study was to validate the SenseWear Pro3 Armband (SWA) step counts during treadmill walking and free-living conditions.

Methods: Study 1 observed 39 individuals (17 males, 22 females) wearing an SWA and a Yamax Digiwalker SW-701 pedometer (DIGI) during treadmill walking, utilizing manually counted steps as the criterion. Study 2 compared free-living step count data from 35 participants (17 males, 18 females) wearing the SWA and DIGI (comparison) for 3 consecutive days.

Results: During Study 1, the SWA underestimated steps by 16.0%, 10.7%, 5.6%, 6.1%, and 6.5% at speeds of 54 m/min, 67 m/min, 80 m/min, 94 m/min, and 107 m/min, respectively, compared to manually counted steps. During Study 2, the intraclass correlation (ICC) coefficient of mean steps/d between the SWA and DIGI was strong (r = 0.98, p < 0.001). Unlike Study 1, the SWA overestimated step counts during the 3-day wear period by an average of 1028 steps/d (or +11.3%) compared to the DIGI. When analyzed individually, the SWA consistently overestimated step counts for each day (p < 0.05).

Conclusion: The SWA underestimates steps during treadmill walking and appears to overestimate steps during free-living compared to the DIGI pedometer. Caution is warranted when using the SWA to count steps. Modifications are needed to enhance step counting accuracy.

Keywords: Accelerometry; Armband; Assessment; Evaluation; Physical activity.

Figures

Fig. 1

Effect of speed on monitor accuracy (% of manual count) during treadmill walking.

Fig. 2

Bland–Altman plots comparing the results of the number of steps recorded between the SenseWear Armband (SWA) and manually counted steps during treadmill walking at 67 m/min.

Fig. 3

Bland–Altman plots comparing the results of the number of steps recorded between the SenseWear Armband (SWA) and manually counted steps during treadmill walking at 94 m/min.

Fig. 4

Bland–Altman plots comparing the results of the average daily steps recorded between the SenseWear Armband (SWA) and Yamax SW-701 (criterion) during free-living.