Poster D5 - GAIT METRICS DURING STANDARD AND NOVEL ASSESSMENT OF WALKING

Friday, October 25, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Brenna Baker

Undergraduate Research Assistant
University of Pittsburgh
Aurora, Ohio, United States

Primary Investigator(s)

RC

Rakie Cham

Professor
University of Pittsburgh, United States

Co-Author(s)

GH

Galen Holland

Research Engineer
University of Pittsburgh, United States
WS

William Smith

Director of Low Vision Clinic
UPMC, United States
MR

Mark Redfern, PhD

Professor
University of Pittsburgh, United States

Introduction: Mobility is critical to independence and increased quality of life, but as individuals age their mobility is often seen to decrease [1,2]. To assess and improve mobility, in-lab testing, and therapy are typically performed. However, standard laboratory measures of gait, balance, and mobility may not be indicative of how someone moves in daily life. However, assessments of these measures outside of the laboratory present a variety of challenges due to the unpredictability of the environment. The goal of this pilot study is to relate the standard lab assessment of gait to novel assessments in a more ecologically valid environment.

Materials and

Methods: 5 subjects (N=5, 2 males) ages 55 and older (mean ±sd. 63.8±7.9) participated in one visit. Subjects performed a two-minute walking trial both indoors in our controlled lab space and outdoors in a rehabilitation garden. In both trials, participants walked at their normal speed in a counterclockwise direction. The floor type is similar in both spaces with the indoor lab space having laminate flooring and the outdoor garden having smoothed concrete tiles. All participants also completed a multi-terrain walking task that included consecutive straight walking segments of equal length (~10m) on 4 terrains (flat concrete, gravel, turf, and stone) (Fig. 1). Subjects wore 13 APDM Opal IMU (Clario, USA) sensors (128 Hz) for the duration of testing. For gait analysis presented here, only the lumbar sensor was analyzed. Opal data were processed using Matlab (version 2023a, MathWorks, Inc., USA). A transformation matrix was derived to align the data with earth vertical. This was done by applying an NED Kalman Filter to the average values of the accelerometer, magnetometer, and gyroscope from quiet standing. After reorientation, the accelerometer data were filtered using a 3-Hz cut-off, 4th-order, low-pass Butterworth filter. Then the following outcome measures were calculated: step time, cadence, and percent time in single and double support [3]. To calculate gait parameters, only straight walking segments were analyzed (turns removed).

Results, Conclusions, and Discussions:

Results: Qualitative results are presented due to small sample size. Standard gait parameters differed within subjects across different environments/terrains, and these differences were not consistent across subjects. Firstly, there were noticeable differences in cadence within subjects for 2-minute walking trials in-lab and outdoors. Cadence increased for 4 subjects while decreasing slightly for the other (Fig. 2). Average step time was often highest during in-lab walking (Fig. 4). Differences in percent time in double support between indoor and outdoor walking were minimal (Table 1).

The multi-terrain walks also had variation in gait parameters within most subjects. Cadence on all surfaces was higher than for the 2-min walking tasks (Fig. 2). Similarly, average step time on multi-terrain surfaces was lower than the 2-min walking tasks (Fig. 3). Percent time in double support was highest for turf or gravel for all subjects (Table 1).

Conclusions: Gait appears to be affected by the environment in which it is performed. The intra- and inter-subject variability across terrains suggests that indoor laboratory walking measures may not be indicative of more naturalized walking. The unpredictable nature of individuals' gait in ecologically valid environments (outdoor) compared to standard assessments (in-lab) suggests that the use of IMUs in the evaluation of mobility could provide greater insight into individual performance during daily activities.

Discussions: The indoor walking segment had a ~4.5m straight, while the outdoor walking segments had an ~11m straight. This additional distance could allow the subject to reach a higher top speed outside. It is possible that the lower cadence during in-lab trials is not indicative of how a participant would perform in the outside world, ex. walking down the sidewalk. Also, increased cadence seen in multi-terrain tasks compared to 2-min walking tasks may be due to the task's nature (i.e., goal-oriented navigation versus steady-state walking, respectively).

This ongoing pilot study will also include older adults with vision loss. Gait metrics will be compared both within subjects and between low vision and control groups. The results will improve be used to inform future gait assessment development, specifically for the low-vision population.

Acknowledgements (Optional):

References: [1] Patla A.E. et al. (1999). Dimensions of Mobility: Defining the Complexity and Difficulty Associated with Community Mobility. Journal of Aging and Physical Activity, 7, 7-19. [2] Suri A. et al. (2021). Mobility of Older Adults: Gait Quality Measures are associated with Life-Space Assessment Scores. The journals of gerontology. Series A, Biological sciences and medical sciences. [3] Kvist, A., Tinmark, F., Bezuidenhout, L., Reimeringer, M., Conradsson, D. M., & Franzén, E. (2024). Validation of algorithms for calculating spatiotemporal gait parameters during continuous turning using lumbar and foot mounted inertial measurement units. Journal of Biomechanics, 162, 111907.