Validation of a pouch-mounted activPAL3 accelerometer

The activPAL accelerometer is a commonly used device for the assessment of physical activity in cross sectional and intervention research. These devices are usually attached directly to the skin; however, recent studies report problems such as skin irritation associated with this attachment method and therefore adequate alternate methods are needed. The aim of this study was to validate the use of an elasticised pouch to secure an activPAL3c (PAL Technologies, Glasgow, UK) accelerometer for the assessment of sedentary and physical activity behaviours during laboratory and free-living conditions. Twenty-eight healthy adults wore two activPAL3c accelerometers, one secured in an elasticised pouch, and one directly attached to the skin, on the anterior surface of the right thigh during laboratory-based walking at a self-selected pace, treadmill walking at 0.89 m s1, 1.56 m s1 and running at 2.2 m s1, and during free-living conditions. Paired samples t-tests and intraclass correlation coefficients were used to investigate the difference and agreement between accelerometer outputs. No statistically significant difference in step count between pouch-mounted and skin-mounted activPAL3c accelerometers was evident during walking at any speed under laboratory conditions. No statistically significant difference in step count, upright time, sitting time or postural transitions was found between pouch-mounted and skin-mounted activPAL3c accelerometers during free-living conditions. Intraclass correlation coefficients showed a high to very high level of agreement between pouch-mounted and skin-mounted activPAL3c accelerometers for each outcome variable. The use of an elasticised pouch to secure the activPAL3c accelerometer appears to be a valid method of attachment and may offer advantages over direct skin mounting.