doi:10.3390/s25082480engEchevarría-Polo, MarcosMarín, Pedro J.Pueyo, EstherRamos Maqueda, JavierGaratachea, NuriaVariability and reliability of the Axivity AX6 accelerometer in technical and human motion conditionsART-2025-144045This 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−1 and 6 km·h−1 and running at 8 km·h−1 and 10 km·h−1). 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 (p < 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.2025http://zaguan.unizar.es/record/16087110.3390/s25082480http://zaguan.unizar.es/record/160871oai:zaguan.unizar.es:160871info:eu-repo/grantAgreement/ES/DGA/T39-23Rinfo:eu-repo/grantAgreement/ES/MICINN/PID2022-140556OB-I00info:eu-repo/grantAgreement/EUR/MICINN/TED2021-130459B-I00Sensors 25, 8 (2025), 2480 [11 pp.]byhttps://creativecommons.org/licenses/by/4.0/deed.esinfo:eu-repo/semantics/openAccess