Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion Conditions

This study aimed to evaluate the intra- and inter-instrument variability and reliability of the Axivity AX6 accelerometer under controlled technical conditions and human motion scenarios. In the first experiment, 12 accelerometers were affixed to a vibration platform and tested at four frequencies (...

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Bibliographic Details
Main Authors: Marcos Echevarría-Polo, Pedro J. Marín, Esther Pueyo, Javier Ramos Maqueda, Nuria Garatachea
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/8/2480
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Summary:This study aimed to evaluate the intra- and inter-instrument variability and reliability of the Axivity AX6 accelerometer under controlled technical conditions and human motion scenarios. In the first experiment, 12 accelerometers were affixed to a vibration platform and tested at four frequencies (2.2, 3.2, 6.5, and 9.4 Hz) along three axes to assess frequency- and axis-dependent variability. In the second experiment, four AX6 accelerometers were simultaneously placed on a subject’s wrist and tested under four human motion conditions (walking at 4 km·h<sup>−1</sup> and 6 km·h<sup>−1</sup> and running at 8 km·h<sup>−1</sup> and 10 km·h<sup>−1</sup>). Results demonstrated low intra- and inter-instrument variability (CVintra: 3.3–4.5%; CVinter: 6.3–7.7%) with high reliability (ICC = 0.98). Similar results were observed in human motion conditions (CVintra: 5.3–8.8%; CVinter: 7.1–10.4%), with ICC values of 0.98 for combined devices, and 0.99 for each device individually. Despite statistically significant differences (<i>p</i> < 0.05) between devices in human motion all conditions, the variations remained below the minimal clinically significant difference threshold. These findings indicate that under technical conditions on a vibrating platform, and within the range of typical human accelerations, the Axivity AX6 is a reliable tool for measuring accelerations representative of physical activity. However, further research is necessary to validate its performance under free-living conditions.
ISSN:1424-8220