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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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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author Marcos Echevarría-Polo
Pedro J. Marín
Esther Pueyo
Javier Ramos Maqueda
Nuria Garatachea
author_facet Marcos Echevarría-Polo
Pedro J. Marín
Esther Pueyo
Javier Ramos Maqueda
Nuria Garatachea
author_sort Marcos Echevarría-Polo
collection DOAJ
description 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.
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spelling doaj-art-54649e4670fa4f6791ddbca3ca9b65e42025-08-20T02:25:11ZengMDPI AGSensors1424-82202025-04-01258248010.3390/s25082480Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion ConditionsMarcos Echevarría-Polo0Pedro J. Marín1Esther Pueyo2Javier Ramos Maqueda3Nuria Garatachea4EXER-GENUD “Growth, Exercise, NUtrition and Development” Research Group, University of Zaragoza, 50009 Zaragoza, SpainCYMO Research Institute, 47140 Valladolid, SpainBSICos Group, I3A, IIS Aragón, University of Zaragoza, 50018 Zaragoza, SpainBSICos Group, I3A, IIS Aragón, University of Zaragoza, 50018 Zaragoza, SpainEXER-GENUD “Growth, Exercise, NUtrition and Development” Research Group, University of Zaragoza, 50009 Zaragoza, SpainThis 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.https://www.mdpi.com/1424-8220/25/8/2480physical activityaccelerometryactivity monitorreliability
spellingShingle Marcos Echevarría-Polo
Pedro J. Marín
Esther Pueyo
Javier Ramos Maqueda
Nuria Garatachea
Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion Conditions
Sensors
physical activity
accelerometry
activity monitor
reliability
title Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion Conditions
title_full Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion Conditions
title_fullStr Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion Conditions
title_full_unstemmed Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion Conditions
title_short Variability and Reliability of the Axivity AX6 Accelerometer in Technical and Human Motion Conditions
title_sort variability and reliability of the axivity ax6 accelerometer in technical and human motion conditions
topic physical activity
accelerometry
activity monitor
reliability
url https://www.mdpi.com/1424-8220/25/8/2480
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AT estherpueyo variabilityandreliabilityoftheaxivityax6accelerometerintechnicalandhumanmotionconditions
AT javierramosmaqueda variabilityandreliabilityoftheaxivityax6accelerometerintechnicalandhumanmotionconditions
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