Technical variability of the Vivago® wrist-worn accelerometer.

The aim was to assess the technical variability of a new wrist-worn accelerometer under controlled conditions with a shaker device and during normal daily physical activities (PAs). In the first experiment, 10 wrist-worn accelerometers (Vivago(®) Wellness, Paris, France) were attached to the shaker device. Variability was tested at five shaking frequencies (1.1, 2.1, 3.1, 4.1, and 10 Hz) for 10 min at each frequency. In the second experiment, 21 participants wore wrist-worn accelerometers and performed six consecutive 10-min periods of activity at increasing levels of intensity from sedentary to vigorous. Results from the first experiment show a modest inter- and intra-instrument reliability at low frequencies and that reliability improved as frequency increased. The inter-instrument coefficient of variation (CV) was 2.6-18.3%. The intra-instrument CV was 4.1-23.2%. Variability was similar in the second experiment with a CV inversely related to PA intensity. The inter- and intra-instrument CV varied from 24.2% and 19.9% for sedentary activities to 3.7% and 4.3% for vigorous PA, respectively. Results suggest that reliability was higher at high intensities, corresponding to moderate and vigorous PA, intensities generally recommended for public health purposes.