title: Can a single lower trunk body-fixed sensor differentiate between level-walking and stair descent and ascent in older adults? Preliminary findings.
abstract: Stair ascent and descent are common forms of ambulation that may be challenging to detect. Here, we propose the first step towards differentiating between stair negotiation and level-walking using a single body-fixed sensor. Seventeen healthy older adults (age: 79.3±4.2 years, 47% women) wore a body-fixed sensor on the lower-back while performing level-walking and stair negotiation. Measures derived from the 3D acceleration and angular-velocity signals included medians, ranges, step duration, step and stride regularity, filtered vertical to horizontal acceleration ratio (VAF/HAF), and wavelet-based features. Friedman's and Wilcoxon tests compared between conditions. Stepwise-binary logistic-regression evaluated classification accuracy. During level-walking, yaw range was lowest and anterior-posterior and vertical step and stride regularity were highest (p≤0.007). Anterior-posterior step regularity (p=0.003), VAF/HAF (p=0.094), and yaw range (p=0.105) identified level-walking (92.2% accuracy). During stair ascent, roll range, median anterior-posterior acceleration and anterior-posterior wavelet-coefficient were lowest (p≤0.006), while VAF/HAF was highest (p=0.0029). Anterior posterior wavelet coefficient (p=0.038) and VAF/HAF (p=0.018) identified stair ascent (94.3% accuracy). During stair descent, vertical and medio-lateral ranges were highest and medio-lateral stride regularity and VAF/HAF were lowest (p≤0.006). VAF/HAF (p=0.01), medio-lateral acceleration range (p=0.069), and medio-lateral stride regularity (p=0.072) identified stair descent (90.2% accuracy). These findings suggest that a single worn body-fixed sensor can be used to differentiate between level-walking and stair negotiation.
authors.affiliation: Center for the study of Movement, Cognition, and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel. Electronic address: anerw@tlvmc.gov.il.
authors.forename: Aner
authors.initials: A
authors.lastname: Weiss
authors.affiliation: Center for the study of Movement, Cognition, and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors.forename: Marina
authors.initials: M
authors.lastname: Brozgol
authors.affiliation: Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Sieratzki Chair in Neurology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Neurology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Giladi
authors.affiliation: Center for the study of Movement, Cognition, and Mobility, Neurological Institute, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel; Department of Physical Therapy, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hausdorff
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D004856:Postural Balance; D060726:Torso; D016138:Walking / Q000502:physiology*
keywords: Body fixed sensors; Gait; Older adults; Stair descent and ascent; Trunk accelerometer