Investigating the validity of the activPAL accelerometer against the criterion measure of direct observation in people with Parkinson's Disease, in a simulated free-living environment.

Abstract

Purpose: To investigate the validity of the activPAL accelerometer against the criterion measure of direct observation when exploring sedentary and physical activity in people with Parkinson's Disease, in a simulated free-living environment. Design: Cross-sectional, observational, validation study, in a laboratory. Participants: 12 individuals with a diagnosis of Parkinson's Disease, and a Hoehn and Yahr score of ≤3, independently mobile for 5minutes with or without an aid. Method: There were three modules, which involved a range of activities: body positioning and transitions, functional activities, and walking in different environments. Module one comprised lying, sitting and standing; module two required the participant to undertake four activities, chosen from a random selection of eight; and finally in module three the participants were asked to undertake walking in a range of different environments, (indoors/outdoors). Results: When exploring sedentary behaviour (SB), the activPAL was shown to have a 5% error for module one (underestimating SB by 30seconds); module two, a 3% error (underestimating SB by approx. 13 seconds). For physical activity (PA), the activPAL was shown to have less than a 1% error (overestimating PA by 1second); module two, a 3% error (underestimating PA by 8seconds), and module three, less than a 1% error (underestimating PA by 3seconds). Conclusion: The activPAL appears to accurately classify postures and movements, however, it is restricted when there are a number of changes in short timeframes. Further exploration is needed to strengthen and develop these findings before considering the activPAL valid for this population.