Validation Of Accelerometers For Measurement Of Mets During Walking In Independent And Dependent Elderly People

Abstract

We previously confirmed that uni- (Lifecorder (LC), Suzuken Inc., Japan) and tri-axial accelerometers (Activity monitor (AM), Matsushita Electronic Works, Ltd., Japan and Active style Pro (ASP), Omron HealthCare Co., Ltd., Japan) accurately estimated energy expenditure during walking in healthy adults. However, it is unclear whether this is also true in elderly people, especially in very frail populations. PURPOSE: To validate LC, AM, and ASP at three walking speeds in independent and dependent elderly people. METHODS: Volunteers were categorized into four groups: independent elderly (IE, 5 men and 15 women, ages: 76.5±3.3), dependent elderly who walk without any assistive equipment (DE, 7 men and 11 women, ages: 75.3±7.3), dependent elderly who walk with a cane (DE+CANE, 3 men and 5 women, ages: 84.4±8.3), and dependent elderly who walk with a wheeled walker (DE+WALKER, 9 women, ages: 83.1±9.3). Three trials (preferred low, normal, and high walking speeds) were performed. Subjects were equipped with a facemask connected to a Douglas bag, and the LC was attached to the left waist at the midline of the left thigh, the AM to the left waist, and the ASP to the right waist. RESULTS: According to a walking ability test for elderly people, 5 IE were at level 4 and the others were at level 5 (the highest). Among DE, only 1 subject was at level 2 and the others were at level 1 (the lowest). All accelerometers significantly underestimated metabolic equivalents (METs) at all walking speeds in IE (LC: 11.1 to 16.8%, ASP: 6.8 to 10.2%), and the underestimation by AM was greatest with underestimation of 19.6%, 29.1%, and 36.6% at low, normal, and high speeds, respectively. The results were similar in DE at low and normal walking speeds, whereas all accelerometers performed well at the high walking speed. Significant underestimation was found across trials in the DE+CANE (LC: 46.1%, AM: 39.5%, ASP: 27.0% at normal walking speed) and DE+WALKER (LC: 40.4%, AM: 28.9%, ASP: 23.5% at normal walking speed) groups. CONCLUSIONS: The present study suggests that uni- and tri-axial accelerometers often underestimate energy costs during walking in both healthy and frail elderly. In particular, it should be noted that greater underestimation may occur in frail elderly who walk with assistive equipment.