Measuring Free-Living Physical Activity in Adults With and Without Neurologic Dysfunction With a Triaxial Accelerometer

Abstract 

Hale LA, Pal J, Becker I. Measuring free-living physical activity in adults with and without neurologic dysfunction with a triaxial accelerometer.

Objective

To investigate the reliability, validity, and utility of a triaxial accelerometer to measure physical activity in the free-living environment in adults with and without neurologic dysfunction.

Design

Repeated-measures design.

Setting

General community.

Participants

Volunteer sample of 17 men and 30 women (age range, 28−91y) living in the community with stroke of greater than 6 months in duration (n=20), Parkinson disease (n=7), or multiple sclerosis (n=11), and healthy but sedentary controls (n=9).

Interventions

Not applicable.

Main Outcome Measures

Physical activity measured with the TriTrac RT3 accelerometer, 7-day recall questionnaire, and activity diary.

Results

The accelerometer reliably measured free-living physical activity (intraclass correlation coefficient, .85; 95% confidence interval, .74−.91; P=.000). The standard error of measurement indicated that a second test would differ from a baseline test by ±23%. Mean daily RT3 data collected in the first 3 days differed significantly from that of the mean daily RT3 data collected over 7 days. The RT3 appeared to distinguish level of mobility better than the 7-day recall questionnaire, and participants found the RT3 to be a user-friendly and acceptable measure of physical activity.

Conclusions

The triaxial accelerometer provided a stable measure of free-living physical activity, was found to distinguish between people with varying levels of mobility, and was well tolerated by participants. The results indicate that collecting data for 3 days was not reflective of data collected over 7 days.

Key Words: Exercise, Neurologic manifestation, Questionnaires, Rehabilitation

List of Abbreviations: CI, confidence interval, ICC, intraclass correlation coefficient, MS, multiple sclerosis, MVM, mean vector magnitude, PD, Parkinson disease, RMI, Rivermead Mobility Index, ROC, receiver operating characteristic