Examining the Activpal3 monitor in measuring body position and step counts in infants: a validity study

Aims: The primary objective of this study was to investigate the validity of the ActivPAL3 in assessing infant activity measured by body position and step count. Design: Observational Study Method: Twenty infants aged 6-18 months were recruited for this study. Demographic information and physical measures were recorded. Each participant was observed in their home environment for 30-40mins while wearing an ActivPAL3 monitor. Body position and step count were recorded every 15 seconds through a preset behavior mapping protocol (criterion method). The observed activity was compared with the corresponding ActivPAL3 data.Results: The ActivPAL3 showed strong agreement with behavior mapping in identifying sitting (83%), standing (76%) and stepping (74%) body positions. There was a significant correlation between the overall step counts recorded by the ActivPAL3 and behavior mapping (r = 0.780, p = <0.01 ) as well as specific step counts for crawling (r = 0.740, p =<0.01), cruising (r = 0.922, p = <0.01), and stepping (r = 0.896, p = <0.01). Conclusions: The ActivPAL3 has acceptable validity for detecting body position and step count. Further investigations with larger sample sizes and refined behavior mapping technique with video surveillance, is required to corroborate these findings. Key Practice Points: This is the first study examining the use of the ActivPAL3 in infants. The ActivPAL3 may provide physiotherapists working to improve the activity levels of infants with an objective measurement tool to record body position and step count over a longer period of time in a natural setting, enhancing parental self-reports and clinical examination.