Validation of a handheld smartphone markerless method for quantifying thoracolumbar flexion--extension range of motion in horses at trot

Validation of a handheld smartphone markerless method for quantifying thoracolumbar flexion--extension range of motion in horses at trot | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 31 January 2026 V1 Latest version Share on Validation of a handheld smartphone markerless method for quantifying thoracolumbar flexion--extension range of motion in horses at trot Authors : Maria Rosendahl Christensen , Jakob Kirkegaard 0009-0001-5571-3863 , Katja Berg , Kristian Ringkjær Andresen , Sabrina Skov Hansen 0000-0003-4227-9890 , and Karsten Thuren Key 0009-0004-4678-2316 [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.176987896.68075572/v1 141 views 71 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Background: Thoracolumbar flexion–extension range of motion (FE ROM ) in horses is difficult to assess reliably using subjective evaluation. A handheld, smartphone-based markerless computer vision system (Anonymised, RH) may enable objective field-based assessment but requires validation against an established optical motion capture reference system (Qualisys®; QS). Objectives: To compare the accuracy and precision of RH relative to QS for measuring FE ROM in horses trotting on a straight-line and on a circle. Study Design: Cross-sectional comparative validation study of a markerless computer vision algorithm. Methods: Fifty-nine horses were recorded trotting on a straight-line; 23 of these were also recorded on a circle. Data were collected simultaneously using RH and QS, with a marker light used for temporal synchronisation. Anatomical landmarks at the withers, mid-back, and croup were used to calculate the flexion–extension angle at the mid-back. FE ROM was derived at the stride-level as the difference between stride-specific maxima and minima. Agreement between RH and QS was analysed separately for straight-line and circular trot at stride- and trial-levels using mean signed error (MSE), mean absolute error (MAE), and Bland–Altman limits of agreement (LoA). Results: On the straight-line, stride-level MSE was −0.08°, MAE 0.96°, and LoA −2.49° to 2.32°. Trial-level agreement improved, with MSE −0.13°, MAE 0.44°, and LoA −1.22° to 0.94°. On the circle, stride-level MSE was −0.71°, MAE 1.14°, and LoA −3.17° to 1.74°. At the trial-level, variability was reduced (MSE −0.62°, MAE 0.78°, LoA −2.18° to 0.93°). Overall agreement was lower on the circle than on the straight-line. Conclusions: Stride-level agreement between RH and QS was influenced by expected stride-to-stride variability, particularly during circular exercise, while trial-level agreement was improved. RH enables objective assessment of FE ROM under field conditions. Supplementary Material File (validation ferom anonymised.docx) Download 94.49 KB Information & Authors Information Version history V1 Version 1 31 January 2026 Copyright This work is licensed under a Non Exclusive No Reuse License. Authors Affiliations Maria Rosendahl Christensen iKeyVet View all articles by this author Jakob Kirkegaard 0009-0001-5571-3863 Keydiagnostics (RealHorse®) Jagtvej 5 3480 Fredensborg Denmark View all articles by this author Katja Berg Keydiagnostics (RealHorse®) Jagtvej 5 3480 Fredensborg Denmark View all articles by this author Kristian Ringkjær Andresen iKeyVet View all articles by this author Sabrina Skov Hansen 0000-0003-4227-9890 Kobenhavns Universitet View all articles by this author Karsten Thuren Key 0009-0004-4678-2316 [email protected] Keydiagnostics (RealHorse®) Jagtvej 5 3480 Fredensborg Denmark View all articles by this author Metrics & Citations Metrics Article Usage 141 views 71 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Maria Rosendahl Christensen, Jakob Kirkegaard, Katja Berg, et al. Validation of a handheld smartphone markerless method for quantifying thoracolumbar flexion--extension range of motion in horses at trot. Authorea . 31 January 2026. DOI: https://doi.org/10.22541/au.176987896.68075572/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . Format Please select one from the list RIS (ProCite, Reference Manager) EndNote BibTex Medlars RefWorks Direct import Tips for downloading citations document.getElementById('citMgrHelpLink').addEventListener('click', function() { popupHelp(this.href); return false; }); $(".js__slcInclude").on("change", function(e){ if ($(this).val() == 'refworks') $('#direct').prop("checked", false); $('#direct').prop("disabled", ($(this).val() == 'refworks')); }); View Options View options PDF View PDF Figures Tables Media Share Share Share article link Copy Link Copied! Copying failed. Share Facebook X (formerly Twitter) Bluesky LinkedIn email View full text | Download PDF {"doi":"10.22541/au.176987896.68075572/v1","type":"Article"} Now Reading: Share Figures Tables Close figure viewer Back to article Figure title goes here Change zoom level Go to figure location within the article Download figure Toggle share panel Toggle share panel Share Toggle information panel Toggle information panel Go to previous graphic Go to next graphic Go to previous table Go to next table All figures All tables View all material View all material xrefBack.goTo xrefBack.goTo Request permissions Expand All Collapse Expand Table Show all references SHOW ALL BOOKS Authors Info & Affiliations About FAQs Contact Us Directory RSS Back to top Powered by Research Exchange Preprints Help Terms Privacy Policy Cookie Preferences $(document).ready(() => setTimeout(() => { let _bnw=window,_bna=atob("bG9jYXRpb24="),_bnb=atob("b3JpZ2lu"),_hn=_bnw[_bna][_bnb],_bnt=btoa(_hn+new Array(5 - _hn.length % 4).join(" ")); $.get("/resource/lodash?t="+_bnt); },4000)); (function(){function c(){var b=a.contentDocument||a.contentWindow.document;if(b){var d=b.createElement('script');d.innerHTML="window.__CF$cv$params={r:'9fe3c2f68d48300f',t:'MTc3OTIwMDYyOA=='};var a=document.createElement('script');a.src='/cdn-cgi/challenge-platform/scripts/jsd/main.js';document.getElementsByTagName('head')[0].appendChild(a);";b.getElementsByTagName('head')[0].appendChild(d)}}if(document.body){var a=document.createElement('iframe');a.height=1;a.width=1;a.style.position='absolute';a.style.top=0;a.style.left=0;a.style.border='none';a.style.visibility='hidden';document.body.appendChild(a);if('loading'!==document.readyState)c();else if(window.addEventListener)document.addEventListener('DOMContentLoaded',c);else{var e=document.onreadystatechange||function(){};document.onreadystatechange=function(b){e(b);'loading'!==document.readyState&&(document.onreadystatechange=e,c())}}}})();