Evaluation of a Body-Worn Sensor System to Measure Physical Activity in Older People With Impaired Function
By Taraldsen, Kristin; Askim, Torunn; Sletvold, Olav; Einarsen, Elin Kristin; Bjaastad, Karianne Gruener; Indredavik, Bent; Helbostad, Jorunn Laegdheim; Physical Therapy (PTJ) , Volume 91, Number 2, pages 277-285Publication Date: February 2011
Cross sectional study evaluated the concurrent validity of the activPAL Professional single axis accelerometer in recognizing postures and transitions as well as in step counting in people with acute stroke, older inpatients, and people with hip fracture. Video observations of the same activities were used as the criterion measure. Participants were 14 patients with a diagnosis of acute stroke, 14 older inpatients at a university hospital, and 8 patients with hip fracture that had occurred 3 months earlier. A reference group of 10 healthy adults was included for evaluating whether step counts were dependent on gait speed. Mean age of the 36 people in the test group was 79 years, and 14 were men. Activity data were collected from 3 activPAL sensors attached to the thighs and sternum and from registration of the same activities from video recordings. Participants performed a test protocol of in-bed, transfer, and walking activities. The sensor system was 100 percent accurate in classifying lying, sitting, and standing positions and in recognizing transitions from lying to sitting, and from sitting to standing positions. Placement of a sensor on the nonaffected leg resulted in less underestimation of step counts than placement on the affected leg. However, the sensor system underestimated step counts during walking, especially at walking speeds of less than 0.47 meter per second. Study limitations and implications for future research are discussed.
Published by: American Physical Therapy Association (Website:http://www.apta.org)
Link to text: http://ptjournal.apta.org/content/91/2/277.full
