{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:06:15Z","timestamp":1760058375302,"version":"build-2065373602"},"reference-count":36,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,3,28]],"date-time":"2025-03-28T00:00:00Z","timestamp":1743120000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004242","name":"Princess Nourah bint Abdulrahman University Researchers","doi-asserted-by":"publisher","award":["PNURSP2025R168"],"award-info":[{"award-number":["PNURSP2025R168"]}],"id":[{"id":"10.13039\/501100004242","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>(1) Background: The application of a mathematical formula to human gait at certain phases is a considerable method to avoid the issues associated with complicated procedures of gait assessment. The purpose of this study was to identify the validity and reliability of an angle (the ZAY angle) in estimating and predicting the step length in healthy subjects. (2) Methods: Thirty-three college-aged students participated in this study. For an assessment of each participant\u2019s gait, a 4.5 m walkway was covered with a weight paper roll to mark the participant\u2019s footprints, providing the step lengths of six consecutive steps for two trials. At the same time, a video recording was captured and analyzed by the Coach\u2019s Eye application to determine the step angle (\u00df). The arc length formula was utilized to calculate the ZAY angle (\u03b8). Spearman\u2019s rho correlation coefficient and the interclass correlation coefficient were used to test the validity and reliability of the ZAY angle in determining individualized step lengths in healthy subjects. Simple linear regression was used to test if the calculated angle could significantly predict the step length. (3) Results: The Spearman rho correlation between the analyzed and calculated angles was significant for all three step lengths (p &lt; 0.05). It was found that the calculated angle could significantly predict the step length (\u03b2 = 0.91, p &lt; 0.05). The ICC was very high (p &lt; 0.05). (4) Conclusions: The ZAY angle is a valid and reliable angle that can be used to estimate individualized step lengths. Clinicians could include this angle in their gait analysis profiles to achieve individualized assessment and rehabilitation goals.<\/jats:p>","DOI":"10.3390\/s25072142","type":"journal-article","created":{"date-parts":[[2025,3,28]],"date-time":"2025-03-28T06:06:35Z","timestamp":1743141995000},"page":"2142","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Novel Mathematical Approach to Gait Analysis: The Reliability and Validity of the ZAY Angle for Step Length Estimation in Healthy Adults"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-6044-3828","authenticated-orcid":false,"given":"Ziad M.","family":"Haroun","sequence":"first","affiliation":[{"name":"Department of Musculoskeletal Disorders, Faculty of Physical Therapy, Innovation University, 10th of Ramadan City 7055501, Egypt"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hoda M.","family":"Zakaria","sequence":"additional","affiliation":[{"name":"Department of Neuromuscular Disorders and Its Surgery, Faculty of Physical Therapy, Cairo University, Cairo 12612, Egypt"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6309-3484","authenticated-orcid":false,"given":"Zizi M.","family":"Ibrahim","sequence":"additional","affiliation":[{"name":"Department of Rehabilitation Sciences, College of Health and Rehabilitation Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6888-5480","authenticated-orcid":false,"given":"Osama R.","family":"Abdelraouf","sequence":"additional","affiliation":[{"name":"Physical Therapy Program, Batterjee Medical College, Jeddah 21442, Saudi Arabia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6665-8855","authenticated-orcid":false,"given":"Aya A.","family":"Khalil","sequence":"additional","affiliation":[{"name":"Department of Biomechanics, Faculty of Physical Therapy, Cairo University, Cairo 12612, Egypt"},{"name":"Department of Biomechanics, Faculty of Physical Therapy, Horus University-Egypt, New Damietta 34517, Egypt"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,3,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/j.jbiomech.2017.11.010","article-title":"A practical step length algorithm using lower limb angular velocities","volume":"66","author":"Allseits","year":"2018","journal-title":"J. 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