Comparison of Two Electronic Physical Performance Batteries by Measurement Time and Sarcopenia Classification.

The Short Physical Performance Battery (SPPB) is a widely accepted test for measuring lower extremity function in older adults. However, there are concerns regarding the examination time required to conduct a complete SPPB consisting of three components (walking speed, chair rise, and standing balance tests) in clinical settings. We aimed to assess specific examination times for each component of the electronic Short Physical Performance Battery (eSPPB) and compare the ability of the original three-component examinations (eSPPB) and a faster, two-component examination without a balance test (electronic Quick Physical Performance Battery, eQPPB) to classify sarcopenia. The study was a retrospective, cross-sectional study which included 124 ambulatory outpatients who underwent physical performance examination at a geriatric clinic of a tertiary, academic hospital in Seoul, Korea, between December 2020 and March 2021. For eSPPB, we used a toolkit containing sensors and software (Dyphi, Daejeon, Korea) developed to measure standing balance, walking speed, and chair rise test results. Component-specific time stamps were used to log the raw data. Duration of balance examination, 5 times sit-to-stand test (5XSST), and walking speed examination were calculated. Sarcopenia was determined using the 2019 Asian Working Group for Sarcopenia (AWGS) guideline. The median age was 78 years (interquartile range, IQR: 73,82) and 77 subjects (62.1%) were female. The total mean eSPPB test time was 124.8 ± 29.0 s (balance test time 61.8 ± 12.3 s, 49.5%; gait speed test time 34.3 ± 11.9 s, 27.5%; and 5XSST time 28.7 ± 19.1 s, 23.0%). The total mean eQPPB test time was 63.0 ± 25.4 s. Based on the AWGS criteria, 34 (27.4%) patient's results were consistent with sarcopenia. C-statistics for classifying sarcopenia were 0.83 for eSPPB and 0.85 for eQPPB (p = 0.264), while eQPPB took 49.5% less measurement time compared with eSPPB. Breakdowns of eSPPB test times were identified. Omitting balance tests may reduce test time without significantly affecting the classifying ability of eSPPB for sarcopenia.

Comparison of Human Interpretation and a Rule-Based Algorithm for Instrumented Sit-to-Stand Test.

BACKGROUND: The five times sit-to-stand test (5STS) is one of the most commonly used tests to assess the physical performance of lower extremities. This study assessed the correlation between human interpretation (5STShuman) and a rule-based algorithm (5STSrule) using instrumented 5STS with two sensors. METHODS: We analyzed clinical records of 148 patients who visited the geriatric outpatient clinic of Asan Medical Center between December 2020 and March 2021 and underwent physical performance assessment using the electronic Short Physical Performance Battery (eSPPB) protocol. For STS, time-weight and time-distance curves were constructed using a loadcell and light detection and ranging (LiDAR). We manually assessed the grids of these curves to calculate 5STShuman, while 5STSrule used an empirical rule-based algorithm. RESULTS: In the study population, the mean 5STShuman and 5STSrule times, i.e., 12.2±0.4 and 11.4±0.4 seconds, respectively, did not differ significantly (p=0.232). Linear regression analysis showed that 5STShuman and 5STSrule were positively correlated (ß=0.99, R2=0.99). The measures also did not differ (p=0.381) in classifying sarcopenia according to the Asian Working Group Society criteria, with C-indices of 0.826 for 5STShuman and 0.820 for 5STSrule. CONCLUSION: An empirical rule-based algorithm correlated with human-interpreted 5STS and had comparable classification ability for sarcopenia.

Development and Validation of 2D-LiDAR-Based Gait Analysis Instrument and Algorithm.

Acquiring gait parameters from usual walking is important to predict clinical outcomes including life expectancy, risk of fall, and neurocognitive performance in older people. We developed a novel gait analysis tool that is small, less-intrusive and is based on two-dimensional light detection and ranging (2D-LiDAR) technology. Using an object-tracking algorithm, we conducted a validation study of the spatiotemporal tracking of ankle locations of young, healthy participants (n = 4) by comparing our tool and a stereo camera with the motion capture system as a gold standard modality. We also assessed parameters including step length, step width, cadence, and gait speed. The 2D-LiDAR system showed a much better accuracy than that of a stereo camera system, where mean absolute errors were 46.2 ± 17.8 mm and 116.3 ± 69.6 mm, respectively. Gait parameters from the 2D-LiDAR system were in good agreement with those from the motion capture system (r = 0.955 for step length, r = 0.911 for cadence). Simultaneous tracking of multiple targets by the 2D-LiDAR system was also demonstrated. The novel system might be useful in space and resource constrained clinical practice for older adults.

Validation of a Multi-Sensor-Based Kiosk for Short Physical Performance Battery.

OBJECTIVES: We aimed to validate a multi-sensor-based kiosk (automatically measured Short Physical Performance Battery [eSPPB] kiosk) that can perform automated measurement of the SPPB. DESIGN: Prospective, cross-sectional study. SETTING: Rehabilitation clinic of a tertiary-care hospital. PARTICIPANTS: Ambulatory outpatients, aged 65 years or older (N = 40). MEASUREMENTS: The eSPPB kiosk was developed to measure the three components of the SPPB: standing balance, gait speed, and chair stand test with embedded sensors and algorithms. Correlations between the total and component-specific scores of the eSPPB and manually measured SPPB (mSPPB), assessed by a physical therapist, were assessed. Further, correlations between SPPB parameters and geriatric functional measures were also evaluated. RESULTS: This study included 40 participants with a mean age of 74.4 ± 6.5 years, a mean total eSPPB score of 10.1 ± 2.1, and a mean total mSPPB score of 10.2 ± 2.1. The intraclass correlation coefficient between the eSPPB and mSPPB total score was 0.97 (P < .001), and the κ agreement was 0.79 (P < .001). The intraclass coefficients between the components of eSPPB and mSPPB were 0.77 (P < .001), 0.88 (P < .001), and 0.99 (P < .001) for standing balance, gait speed, and chair stand test, respectively. CONCLUSION: The newly developed kiosk might be a viable and efficient method for performing the SPPB in older adults. J Am Geriatr Soc 67:2605-2609, 2019.

Cross-Comparisons of Gait Speeds by Automatic Sensors and a Stopwatch to Provide Converting Formula Between Measuring Modalities.

BACKGROUND: We aimed to compare 4 automatic devices with a conventional stopwatch for measuring gait speed. METHODS: We used 4 experimental devices to automatically measure gait speed: 1) Gaitspeedometer (GSM) 1, with laser sensors; 2) GSM2, with ultrasound sensors; 3) GSM3, with infrared sensors; and 4) GSM4, with a light detection and ranging sensor. To assess compatibility between different versions of GSMs, we collected 426 data points from 4 young engineers walking at random speeds and with varying postures. We used these data to convert gait speed measured by GSM1 and 2 for compatibility with GSM3 in the Korean Frailty and Aging Cohort Study (KFACS) dataset. RESULTS: Mean gait speeds measured with GSMs 1-4 were 1.7% slower (R2=0.997), 12.2% faster (R2=0.993), 1.3% slower (R2=0.999), and 4.3% slower (R2=0.996), respectively, than the gait speed measured with a stopwatch. The concordance correlation coefficient between each GSM and the stopwatch was higher than 0.9. Using linear regression analysis with no constant term, conversion formulas for GSMs were established for the KFACS dataset using GSM1 and GSM2. CONCLUSION: The 4 methods of automatic gait speed measurement and the manually measured gait speed correlated well with each other, and we hope these new technologies reduce barriers to measuring older people's gait speed in busy clinical settings.

Accurate Mobile Urban Mapping via Digital Map-Based SLAM.

This paper presents accurate urban map generation using digital map-based Simultaneous Localization and Mapping (SLAM). Throughout this work, our main objective is generating a 3D and lane map aiming for sub-meter accuracy. In conventional mapping approaches, achieving extremely high accuracy was performed by either (i) exploiting costly airborne sensors or (ii) surveying with a static mapping system in a stationary platform. Mobile scanning systems recently have gathered popularity but are mostly limited by the availability of the Global Positioning System (GPS). We focus on the fact that the availability of GPS and urban structures are both sporadic but complementary. By modeling both GPS and digital map data as measurements and integrating them with other sensor measurements, we leverage SLAM for an accurate mobile mapping system. Our proposed algorithm generates an efficient graph SLAM and achieves a framework running in real-time and targeting sub-meter accuracy with a mobile platform. Integrated with the SLAM framework, we implement a motion-adaptive model for the Inverse Perspective Mapping (IPM). Using motion estimation derived from SLAM, the experimental results show that the proposed approaches provide stable bird's-eye view images, even with significant motion during the drive. Our real-time map generation framework is validated via a long-distance urban test and evaluated at randomly sampled points using Real-Time Kinematic (RTK)-GPS.

Thermal stability of superhydrophobic, nanostructured surfaces.

The thermal stability of superhydrophobic, nanostructured surfaces after thermal annealing was explored. Flat surfaces coated with hydrophobic diamond-like carbon (DLC) via plasma polymerization of hexamethyldisiloxane (HMDSO) showed a gradual decrease in the water contact angle from 90(o) to 60(o) while nanostructured surfaces maintained superhydrophobicity with more than 150° for annealing temperatures between 25 and 300°C. It was also found that surfaces with nanostructures having an aspect ratio of more than 5.2 may maintain superhydrophobicity for annealing temperatures as high as 350°C; above this temperature, however, the hydrophobicity on surfaces with lower aspect ratio nanostructures gradually degraded. It was observed that regardless of the aspect ratios of the nanostructure, all superhydrophobic surfaces became superhydrophilic after annealing at temperatures higher than 500°C.