{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,22]],"date-time":"2026-04-22T23:39:52Z","timestamp":1776901192784,"version":"3.51.2"},"reference-count":47,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2022,1,29]],"date-time":"2022-01-29T00:00:00Z","timestamp":1643414400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["5IK2CX000729"],"award-info":[{"award-number":["5IK2CX000729"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000005","name":"United States Department of Defense","doi-asserted-by":"publisher","award":["MS170133"],"award-info":[{"award-number":["MS170133"]}],"id":[{"id":"10.13039\/100000005","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100002028","name":"Collins Medical Trust","doi-asserted-by":"publisher","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}],"id":[{"id":"10.13039\/100002028","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100009187","name":"Medical Research Foundation","doi-asserted-by":"publisher","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}],"id":[{"id":"10.13039\/501100009187","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The \u201ctotal distance walked\u201d obtained during a standardized walking test is an integral component of physical fitness and health status tracking in a range of consumer and clinical applications. Wearable inertial sensors offer the advantages of providing accurate, objective, and reliable measures of gait while streamlining walk test administration. The aim of this study was to develop an inertial sensor-based algorithm to estimate the total distance walked using older subjects with impaired fasting glucose (Study I), and to test the generalizability of the proposed algorithm in patients with Multiple Sclerosis (Study II). All subjects wore two inertial sensors (Opals by Clario-APDM Wearable Technologies) on their feet. The walking distance algorithm was developed based on 108 older adults in Study I performing a 400 m walk test along a 20 m straight walkway. The validity of the algorithm was tested using a 6-minute walk test (6MWT) in two sub-studies of Study II with different lengths of a walkway, 15 m (Study II-A, n = 24) and 20 m (Study II-B, n = 22), respectively. The start and turn around points were marked with lines on the floor while smaller horizontal lines placed every 1 m served to calculate the manual distance walked (ground truth). The proposed algorithm calculates the forward distance traveled during each step as the change in the horizontal position from each foot-flat period to the subsequent foot-flat period. The total distance walked is then computed as the sum of walk distances for each stride, including turns. The proposed algorithm achieved an average absolute error rate of 1.92% with respect to a fixed 400 m distance for Study I. The same algorithm achieved an absolute error rate of 4.17% and 3.21% with respect to an averaged manual distance for 6MWT in Study II-A and Study II-B, respectively. These results demonstrate the potential of an inertial sensor-based algorithm to estimate a total distance walked with good accuracy with respect to the manual, clinical standard. Further work is needed to test the generalizability of the proposed algorithm with different administrators and populations, as well as larger diverse cohorts.<\/jats:p>","DOI":"10.3390\/s22031077","type":"journal-article","created":{"date-parts":[[2022,1,30]],"date-time":"2022-01-30T00:12:56Z","timestamp":1643501576000},"page":"1077","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Inertial Sensor Algorithm to Estimate Walk Distance"],"prefix":"10.3390","volume":"22","author":[{"given":"Vrutangkumar V.","family":"Shah","sequence":"first","affiliation":[{"name":"Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5394-4628","authenticated-orcid":false,"given":"Carolin","family":"Curtze","sequence":"additional","affiliation":[{"name":"Department of Biomechanics, University of Nebraska at Omaha, 6001 Dodge St., Omaha, NE 68182, USA"}]},{"given":"Kristen","family":"Sowalsky","sequence":"additional","affiliation":[{"name":"APDM Wearable Technologie\u2014A Clario Company, 2828 S Corbett Ave, Ste 135, Portland, OR 97201, USA"}]},{"given":"Ishu","family":"Arpan","sequence":"additional","affiliation":[{"name":"Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA"}]},{"given":"Martina","family":"Mancini","sequence":"additional","affiliation":[{"name":"Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5794-4155","authenticated-orcid":false,"given":"Patricia","family":"Carlson-Kuhta","sequence":"additional","affiliation":[{"name":"Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA"}]},{"given":"Mahmoud","family":"El-Gohary","sequence":"additional","affiliation":[{"name":"APDM Wearable Technologie\u2014A Clario Company, 2828 S Corbett Ave, Ste 135, Portland, OR 97201, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7704-5459","authenticated-orcid":false,"given":"Fay B.","family":"Horak","sequence":"additional","affiliation":[{"name":"Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA"},{"name":"APDM Wearable Technologie\u2014A Clario Company, 2828 S Corbett Ave, Ste 135, Portland, OR 97201, USA"}]},{"given":"James","family":"McNames","sequence":"additional","affiliation":[{"name":"APDM Wearable Technologie\u2014A Clario Company, 2828 S Corbett Ave, Ste 135, Portland, OR 97201, USA"},{"name":"Department of Electrical and Computer Engineering, Portland State University, 1825 SW Broadway, Portland, OR 97201, USA"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"268","DOI":"10.1212\/WNL.43.2.268","article-title":"Human walking and higher-level gait disorders, particularly in the elderly","volume":"43","author":"Nutt","year":"1993","journal-title":"Neurology"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/S1474-4422(06)70678-0","article-title":"Neurological gait disorders in elderly people: Clinical approach and classification","volume":"6","author":"Snijders","year":"2007","journal-title":"Lancet Neurol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"602","DOI":"10.1016\/j.amjmed.2017.11.051","article-title":"Gait Disorders","volume":"131","author":"Baker","year":"2018","journal-title":"Am. 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