{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,7]],"date-time":"2026-03-07T06:33:04Z","timestamp":1772865184625,"version":"3.50.1"},"reference-count":53,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2020,12,7]],"date-time":"2020-12-07T00:00:00Z","timestamp":1607299200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010428","name":"Innovation and Technology Fund","doi-asserted-by":"publisher","award":["ITS\/262\/18"],"award-info":[{"award-number":["ITS\/262\/18"]}],"id":[{"id":"10.13039\/501100010428","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No. 11732015"],"award-info":[{"award-number":["No. 11732015"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["No. 11972315"],"award-info":[{"award-number":["No. 11972315"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Real-time detection of fatigue in the elderly during physical exercises can help identify the stability and thus falling risks which are commonly achieved by the investigation of kinematic parameters. In this study, we aimed to identify the change in gait variability parameters from inertial measurement units (IMU) during a course of 60 min brisk walking which could lay the foundation for the development of fatigue-detecting wearable sensors. Eighteen elderly people were invited to participate in the brisk walking trials for 60 min with a single IMU attached to the posterior heel region of the dominant side. Nine sets of signals, including the accelerations, angular velocities, and rotation angles of the heel in three anatomical axes, were measured and extracted at the three walking times (baseline, 30th min, and 60th min) of the trial for analysis. Sixteen of eighteen participants reported fatigue after walking, and there were significant differences in the median acceleration (p = 0.001), variability of angular velocity (p = 0.025), and range of angle rotation (p = 0.0011), in the medial\u2013lateral direction. In addition, there were also significant differences in the heel pronation angle (p = 0.005) and variability and energy consumption of the angles in the anterior\u2013posterior axis (p = 0.028, p = 0.028), medial\u2013lateral axis (p = 0.014, p = 0.014), and vertical axis (p = 0.002, p &lt; 0.001). Our study demonstrated that a single IMU on the posterior heel of the dominant side can address the variability of kinematics parameters for elderly performing prolonged brisk walking and could serve as an indicator for walking instability, and thus fatigue.<\/jats:p>","DOI":"10.3390\/s20236983","type":"journal-article","created":{"date-parts":[[2020,12,7]],"date-time":"2020-12-07T21:37:42Z","timestamp":1607377062000},"page":"6983","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":12,"title":["Identifying Fatigue Indicators Using Gait Variability Measures: A Longitudinal Study on Elderly Brisk Walking"],"prefix":"10.3390","volume":"20","author":[{"given":"Guoxin","family":"Zhang","sequence":"first","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"}]},{"given":"Ivy Kwan-Kei","family":"Wong","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"}]},{"given":"Tony Lin-Wei","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"}]},{"given":"Tommy Tung-Ho","family":"Hong","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8805-1157","authenticated-orcid":false,"given":"Duo Wai-Chi","family":"Wong","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"},{"name":"Shenzhen Research Institute, The Hong Kong Polytechnic University, Shenzhen 518057, China"}]},{"given":"Yinghu","family":"Peng","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"}]},{"given":"Fei","family":"Yan","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"}]},{"given":"Yan","family":"Wang","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"},{"name":"Shenzhen Research Institute, The Hong Kong Polytechnic University, Shenzhen 518057, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1789-0778","authenticated-orcid":false,"given":"Qitao","family":"Tan","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6027-4594","authenticated-orcid":false,"given":"Ming","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China"},{"name":"Shenzhen Research Institute, The Hong Kong Polytechnic University, Shenzhen 518057, China"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"16218","DOI":"10.1097\/MD.0000000000016218","article-title":"Physical activity programs for balance and fall prevention in elderly: A systematic review","volume":"98","author":"Thomas","year":"2019","journal-title":"Medicine"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/1479-5868-7-38","article-title":"Physical activity and functional limitations in older adults: A systematic review related to Canada\u2019s Physical Activity Guidelines","volume":"7","author":"Paterson","year":"2010","journal-title":"Int. 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