Abstract—Dual-task gait allows assessment of impaired executive function and mobility control in older individuals, which are risk factors of falls. This study investigated gait changes in older individuals due to the addition of a cognitive load, using wearable pressure-sensing insole and tri-axial accelerometer measures. These wearable sensors can be applied at the point-of-care. Eleven elderly (65 years or older) individuals walked 7.62 m with and without a verbal fluency cognitive load task while wearing FScan 3000E pressure- sensing insoles in both shoes and a Gulf Coast X16-1C tri-axial accelerometer at the pelvis. Plantar-pressure derived parameters included center of force (CoF) path and temporal measures. Acceleration derived measures were descriptive statistics, Fast Fourier Transform quartile, ratio of even-to-odd harmonics, and maximum Lyapunov exponent. Stride time, stance time, and swing time all significantly increased during dual-task compared to single-task walking. Minimum, mean, and median CoF stance velocity; cadence; and vertical, anterior-posterior, and medial-lateral harmonic ratio all significantly decreased during dual-task walking. Wearable plantar pressure-sensing insole and lower back accelerometer derived-measures can identify gait differences between single- task and dual-task walking in older individuals and could be used in point-of-care environments to assess for deficits in executive function and mobility impairments. I. INTRODUCTION Traditionally, dynamic stability was thought to require minimal cognitive resources and was primarily controlled by automatic or reflex motor responses [1]. However, recent evidence [2] suggests that maintaining stability requires sensorimotor and cognitive processes, particularly executive function and attention [3,4], with a positive relationship between cognitive impairment and gait abnormalities [5,6]. Furthermore, a cautious, conservative gait pattern, often adopted by older individuals, may require more cognitive control and result in gait deterioration under attention- demanding, dual-task (DT) conditions [7]. Research supported by Natural Sciences and Engineering Research Council of Canada (NSERC). J.D. Howcroft is with the Department of Systems Design Engineering at the University of Waterloo, Waterloo, ON, Canada N2L 3G1 (phone: 519- 888-4567; fax: 519-746-4791; e-mail: jirwin02@gmail.com). E.D. Lemaire is with the Ottawa Hospital Rehabilitation Centre, Ottawa, ON, Canada and the University of Ottawa, Canada (e-mail: elemaire@ toh.on.ca). J. Kofman is with the Department of Systems Design Engineering at the University of Waterloo, Waterloo, ON, Canada N2L 3G1 (e-mail: jkofman @uwaterloo.ca). W.E. McIlroy is with the Department of Kinesiology at the University of Waterloo, Waterloo, ON, Canada N2L 3G1 (e-mail: wmcilroy@ uwaterloo.ca). DT gait involves walking while simultaneously performing an attention-demanding task and is assessed in older individuals to identify impaired executive function, particularly the inability to appropriately allocate attention [8] and increased attentional demands associated with impaired control of walking. Impaired executive function and impaired mobility control can increase fall risk [4]. For older individuals, DT walking has been associated with the following gait changes compared to single-task (ST) walking: reduced walking speed [1,7,9-19]; decreased stride frequency [7]; increased percentage of missteps [20]; increased step duration [13]; increased stride time [7]; increased stance time [19]; increased [19] and decreased swing time [15,17]; increased variability in swing time [15,17], stride-to-stride gait velocity [1], stride time [7,18], and stride length [18]; increased phase variability index [7]; decreased root mean square and peak anterior-posterior (AP) and medial-lateral (ML) trunk accelerations [7]; increased local stability exponent for AP and ML trunk accelerations [7]; and increased sample entropy for AP trunk accelerations [7]. Older individuals tend to prioritize motor tasks over cognitive tasks in a DT scenario [16,19,21], as an unconscious, protective strategy to reduce fall risk [21]. Wearable sensors could be applied at the point-of-care to evaluate gait deterioration under attention-demanding, DT conditions. Inertial wearable-sensors [7,13,14] and force- sensitive wearable-insoles [15,17] have been successfully used to detect change in elderly gait between ST and DT walking. Inertial wearable-sensors have been applied to the lower leg [13,14], head [13], and trunk [7]. However, the lower back location has not yet been assessed even though it has advantages over other locations since it approximates the center of mass location and can be easily used by attaching the sensor to a belt [22]. Most wearable-sensor-derived measures for DT walking have been temporal measures. Only Lamoth et al. 2011 [7] identified non-temporal changes in gait under DT conditions in older individuals. Non- temporal measures may further elucidate gait pattern changes under DT walking conditions. This study investigated gait changes in older individuals due to the addition of a cognitive load using wearable pressure-sensing insole and tri-axial accelerometer measures. II. METHOD A. Participants Eleven elderly independent community dwellers or residents of retirement homes voluntarily participated in this Analysis of Dual-Task Elderly Gait Using Wearable Plantar-Pressure Insoles and Accelerometer Jennifer D. Howcroft, IEEE EMBS Student Member, Edward D. Lemaire, IEEE Member, Jonathan Kofman, IEEE EMBS Member, and William E. McIlroy 978-1-4244-7929-0/14/$26.00 ©2014 IEEE 5003