Determining minimum number of valid days for accurate estimation of sedentary behaviour and awake‑time movement behaviours using the ActivPAL3 in nursing home residents

Abstract

Introduction Scarce evidence is available about the minimum number of valid days wearing the activPAL3 to obtain a precise estimate of sedentary behaviour (SB) and awake-time movement behaviours (ATMB) in nursing home (NH) residents. The study aimed to determine the minimum number of valid days required for accurately estimate SB and ATMB using the activPAL3 device in NH residents. It also investigated how the starting point of a day (the 24-h period) impacted reliability. Methods Participants wore an activPAL3 for 7 consecutive days. The data was classifed in two-time blocks (00:00 Ante Meridiem (AM)—00:00 AM midnight vs 12:00 Post Meridiam (PM) -12:00 PM midday) and the sample was strati‑ fed into two groups according to their capacity to stand and walk, to examine if timing of sampling or physical functioning afected minimum wear time. SB, ATMB, sociodemographic, and health-related variables were collected. Sensitivity of the time-blocks were tested through the dispersion frequencies and diferences between blocks through Kolmogorov–Smirnov test for normality; parametric variables through two-related means T-test and Wil‑ coxon test for non-parametric data. Reliability was assessed with the Cronbach’s Alpha and the intra-class correlation coefcient (ICC), using a one-factor model estimating the reliability for each measurement day loading in the same latent factor. Results Ninety-fve NH residents (81.1% women; age=85.8±7.2 years) were included. The midnight block had higher reliability, sensitivity and no statistically signifcant diferences between days were found. At least three consecutive days of monitoring were necessary to achieve a reliability of ICC≥0.8 for those NH residents able to stand and walk and six days for those unable. Conclusions NH residents who are able to stand and walk require a minimum of three consecutive days wear‑ ing the device, while those who are unable require at least six days due to their highly homogenous daily routines and sensitivity to PA events. Regardless of the activPAL3 recording start time, data processing should reference the midnight time block.