{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T21:40:08Z","timestamp":1785534008584,"version":"3.56.0"},"reference-count":37,"publisher":"Public Library of Science (PLoS)","issue":"11","license":[{"start":{"date-parts":[[2021,11,15]],"date-time":"2021-11-15T00:00:00Z","timestamp":1636934400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000690","name":"Research Councils UK","doi-asserted-by":"publisher","award":["EP\/M023281\/1"],"award-info":[{"award-number":["EP\/M023281\/1"]}],"id":[{"id":"10.13039\/501100000690","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000690","name":"Research Councils UK","doi-asserted-by":"crossref","award":["EP\/T014865\/1"],"award-info":[{"award-number":["EP\/T014865\/1"]}],"id":[{"id":"10.13039\/501100000690","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>This study describes the development, evaluation and application of a computer vision and deep learning system capable of capturing sprinting and skeleton push start step characteristics and mass centre velocities (sled and athlete). Movement data were captured concurrently by a marker-based motion capture system and a custom markerless system. High levels of agreement were found between systems, particularly for spatial based variables (step length error 0.001 \u00b1 0.012 m) while errors for temporal variables (ground contact time and flight time) were on average within \u00b1 1.5 frames of the criterion measures. Comparisons of sprinting and pushing revealed decreased mass centre velocities as a result of pushing the sled but step characteristics were comparable to sprinting when aligned as a function of step velocity. There were large asymmetries between the inside and outside leg during pushing (e.g. 0.22 m mean step length asymmetry) which were not present during sprinting (0.01 m step length asymmetry). The observed asymmetries suggested that force production capabilities during ground contact were compromised for the outside leg. The computer vision based methods tested in this research provide a viable alternative to marker-based motion capture systems. Furthermore, they can be deployed into challenging, real world environments to non-invasively capture data where traditional approaches are infeasible.<\/jats:p>","DOI":"10.1371\/journal.pone.0259624","type":"journal-article","created":{"date-parts":[[2021,11,15]],"date-time":"2021-11-15T18:30:32Z","timestamp":1637001032000},"page":"e0259624","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":12,"title":["Development, evaluation and application of a novel markerless motion analysis system to understand push-start technique in elite skeleton athletes"],"prefix":"10.1371","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8675-4684","authenticated-orcid":true,"given":"Laurie","family":"Needham","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Murray","family":"Evans","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Darren P.","family":"Cosker","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4973-6591","authenticated-orcid":true,"given":"Steffi L.","family":"Colyer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2021,11,15]]},"reference":[{"issue":"1","key":"pone.0259624.ref001","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1123\/jab.13.1.98","article-title":"Analysis of the bobsled and men\u2019s luge events at the XVII Olympic winter games in Lillehammer","volume":"13","author":"GP Bruggemann","year":"1997","journal-title":"Journal of Applied Biomechanics"},{"issue":"3","key":"pone.0259624.ref002","first-page":"579","article-title":"Relationship between push phase and final race time in skeleton performance","volume":"20","author":"C Zanoletti","year":"2006","journal-title":"Journal of Strength and Conditioning Research"},{"issue":"17","key":"pone.0259624.ref003","doi-asserted-by":"crossref","first-page":"1930","DOI":"10.1080\/02640414.2018.1426352","article-title":"The effect of altering loading distance on skeleton start performance: Is higher pre-load velocity always beneficial?","volume":"36","author":"SL Colyer","year":"2018","journal-title":"Journal of Sports Sciences"},{"issue":"2","key":"pone.0259624.ref004","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1080\/14763141.2016.1261183","article-title":"Skeleton sled velocity profiles: a novel approach to understand critical aspects of the elite athletes\u2019 start phases","volume":"17","author":"SL Colyer","year":"2018","journal-title":"Sports Biomechanics"},{"issue":"1","key":"pone.0259624.ref005","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1123\/ijspp.2015-0631","article-title":"Physical Predictors of Elite Skeleton Start Performance","volume":"12","author":"SL Colyer","year":"2017","journal-title":"International Journal of Sports Physiology and Performance"},{"issue":"3\u20134","key":"pone.0259624.ref006","doi-asserted-by":"crossref","first-page":"346","DOI":"10.1007\/BF02425497","article-title":"The specificity of strength training: The effect of posture","volume":"73","author":"GJ Wilson","year":"1996","journal-title":"European Journal of Applied Physiology and Occupational Physiology"},{"issue":"2","key":"pone.0259624.ref007","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1123\/ijspp.1.2.74","article-title":"Transfer of Strength and Power Training to Sports Performance","volume":"1","author":"WB Young","year":"2006","journal-title":"International Journal of Sports Physiology and Performance"},{"issue":"10","key":"pone.0259624.ref008","doi-asserted-by":"crossref","first-page":"1089","DOI":"10.1080\/02640410500130763","article-title":"The conceptual process of skill progression development in artistic gymnastics","volume":"23","author":"G Irwin","year":"2005","journal-title":"Journal of Sports Sciences"},{"key":"pone.0259624.ref009","first-page":"4","article-title":"A Review of the Evolution of Vision-Based Motion Analysis and the Integration of Advanced Computer Vision Methods Towards Developing a Markerless System","author":"SL Colyer","year":"2018","journal-title":"Sports Medicine-Open"},{"key":"pone.0259624.ref010","volume-title":"Deep learning","author":"I Goodfellow","year":"2016"},{"key":"pone.0259624.ref011","doi-asserted-by":"crossref","unstructured":"Evans M, Colyer S, Cosker D, Salo A, Ieee, editors. Foot Contact Timings and Step Length for Sprint Training. 18th IEEE Winter Conference on Applications of Computer Vision (WACV); 2018 Mar 12\u201315; Nv2018.","DOI":"10.1109\/WACV.2018.00184"},{"issue":"1","key":"pone.0259624.ref012","first-page":"756","article-title":"USING COMPUTER VISION AND DEEP LEARNING METHODS TO CAPTURE SKELETON PUSH START PERFORMANCE CHARACTERISTICS","volume":"38","author":"L Needham","year":"2020","journal-title":"ISBS Proceedings Archive"},{"key":"pone.0259624.ref013","doi-asserted-by":"crossref","unstructured":"Evans M, Needham L, Colyer SL, Cosker DP, editors. A Non-Invasive Vision-Based Approach to Velocity Measurement of Skeleton Training. Proceedings of the IEEE\/CVF Conference on Computer Vision and Pattern Recognition Workshops; 2020.","DOI":"10.1109\/CVPRW50498.2020.00452"},{"issue":"11","key":"pone.0259624.ref014","doi-asserted-by":"crossref","first-page":"1330","DOI":"10.1109\/34.888718","article-title":"A flexible new technique for camera calibration","volume":"22","author":"ZY Zhang","year":"2000","journal-title":"Ieee Transactions on Pattern Analysis and Machine Intelligence"},{"key":"pone.0259624.ref015","doi-asserted-by":"crossref","unstructured":"Triggs B, Zisserman A, Szeliski R. Vision Algorithms: Theory and Practice: International Workshop on Vision Algorithms Corfu, Greece, September 21\u201322, 1999 Proceedings: Springer; 2003.","DOI":"10.1007\/3-540-44480-7"},{"issue":"9","key":"pone.0259624.ref016","doi-asserted-by":"crossref","first-page":"1223","DOI":"10.1016\/0021-9290(95)00178-6","article-title":"Adjustments to Zatsiorsky-Seluyanov\u2019s segment inertia parameters","volume":"29","author":"P de Leva","year":"1996","journal-title":"Journal of Biomechanics"},{"issue":"16","key":"pone.0259624.ref017","doi-asserted-by":"crossref","first-page":"4128","DOI":"10.1016\/j.jbiomech.2016.10.013","article-title":"A kinematic algorithm to identify gait events during running at different speeds and with different footstrike types","volume":"49","author":"JC Handsaker","year":"2016","journal-title":"Journal of Biomechanics"},{"key":"pone.0259624.ref018","article-title":"Cross-domain complementary learning using pose for multi-person part segmentation","author":"K Lin","year":"2020","journal-title":"IEEE Transactions on Circuits and Systems for Video Technology"},{"key":"pone.0259624.ref019","doi-asserted-by":"crossref","unstructured":"Guler RA, Neverova N, Kokkinos L, Ieee, editors. DensePose: Dense Human Pose Estimation In The Wild. 31st IEEE\/CVF Conference on Computer Vision and Pattern Recognition (CVPR); 2018 Jun 18\u201323; Salt Lake City, UT2018.","DOI":"10.1109\/CVPR.2018.00762"},{"issue":"7","key":"pone.0259624.ref020","doi-asserted-by":"crossref","first-page":"565","DOI":"10.1038\/s41592-019-0470-3","article-title":"Moving beyond P values: data analysis with estimation graphics","volume":"16","author":"J Ho","year":"2019","journal-title":"Nature Methods"},{"issue":"6522","key":"pone.0259624.ref021","doi-asserted-by":"crossref","first-page":"746","DOI":"10.1136\/bmj.292.6522.746","article-title":"Confidence intervals rather than P values: estimation rather than hypothesis testing","volume":"292","author":"MJ Gardner","year":"1986","journal-title":"Br Med J (Clin Res Ed)"},{"issue":"37","key":"pone.0259624.ref022","first-page":"16","article-title":"COMPUTER-INTENSIVE STATISTICAL-INFERENCE\u2014A CITATION CLASSIC COMMENTARY ON BOOTSTRAP METHODS\u2014ANOTHER LOOK AT THE JACKKNIFE BY EFRON, B","author":"B Efron","year":"1989","journal-title":"Current Contents\/Engineering Technology & Applied Sciences"},{"key":"pone.0259624.ref023","volume-title":"Statistical power analysis for the behavioral sciences","author":"J Cohen","year":"1988"},{"key":"pone.0259624.ref024","unstructured":"Healy R, Kenny IC, Harrison AJ, editors. Estimating step parameters using photoelectric cells. ISBS-Conference Proceedings Archive; 2015."},{"key":"pone.0259624.ref025","volume-title":"BioMEMS and nanotechnology II","author":"B Purcell","year":"2006"},{"issue":"3","key":"pone.0259624.ref026","doi-asserted-by":"crossref","first-page":"332","DOI":"10.1016\/j.jbiomech.2015.12.035","article-title":"Gait recording with inertial sensors\u2014How to determine initial and terminal contact","volume":"49","author":"K Botzel","year":"2016","journal-title":"Journal of Biomechanics"},{"issue":"3","key":"pone.0259624.ref027","doi-asserted-by":"crossref","first-page":"306","DOI":"10.1123\/jab.2015-0200","article-title":"Validation of a Torso-Mounted Accelerometer for Measures of Vertical Oscillation and Ground Contact Time During Treadmill Running","volume":"32","author":"R Watari","year":"2016","journal-title":"Journal of Applied Biomechanics"},{"issue":"5","key":"pone.0259624.ref028","doi-asserted-by":"crossref","DOI":"10.3390\/s20051448","article-title":"Pressure-Sensitive Insoles for Real-Time Gait-Related Applications","volume":"20","author":"E Martini","year":"2020","journal-title":"Sensors"},{"issue":"6","key":"pone.0259624.ref029","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1055\/s-0031-1301313","article-title":"Measurement Error in Estimates of Sprint Velocity from a Laser Displacement Measurement Device","volume":"33","author":"NE Bezodis","year":"2012","journal-title":"International Journal of Sports Medicine"},{"issue":"4","key":"pone.0259624.ref030","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1519\/SSC.0000000000000460","article-title":"Sled Pushing and Pulling to Enhance Speed Capability","volume":"41","author":"MJ Cahill","year":"2019","journal-title":"Strength and Conditioning Journal"},{"issue":"4","key":"pone.0259624.ref031","first-page":"760","article-title":"Effects of resisted sled towing on sprint kinematics in field-sport athletes","volume":"17","author":"RG Lockie","year":"2003","journal-title":"Journal of Strength and Conditioning Research"},{"issue":"6","key":"pone.0259624.ref032","doi-asserted-by":"crossref","first-page":"1992","DOI":"10.1519\/JSC.0b013e31818746fe","article-title":"KINEMATIC ALTERATIONS DUE TO DIFFERENT LOADING SCHEMES IN EARLY ACCELERATION SPRINT PERFORMANCE FROM STARTING BLOCKS","volume":"22","author":"PS Maulder","year":"2008","journal-title":"Journal of Strength and Conditioning Research"},{"issue":"3","key":"pone.0259624.ref033","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1007\/s00421-017-3796-5","article-title":"A comparison between the force-velocity relationships of unloaded and sled-resisted sprinting: single vs. multiple trial methods","volume":"118","author":"MR Cross","year":"2018","journal-title":"European Journal of Applied Physiology"},{"issue":"10","key":"pone.0259624.ref034","doi-asserted-by":"crossref","first-page":"1140","DOI":"10.1080\/02640414.2020.1743065","article-title":"A biomechanical approach to evaluate overload and specificity characteristics within physical preparation exercises","volume":"38","author":"A Brazil","year":"2020","journal-title":"Journal of Sports Sciences"},{"key":"pone.0259624.ref035","unstructured":"Colyer SL, Stokes KA, Bilzon JL, Salo AI, editors. The influence of changes in sprint ability on the sled velocity profile during the skeleton start. Proceedings of the XXXIV International Conference on Biomechanics in Sports Japan: University of Tsukuba; 2016."},{"issue":"2","key":"pone.0259624.ref036","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1249\/01.MSS.0000113664.15777.53","article-title":"Interaction of step length and step rate during sprint running","volume":"36","author":"JP Hunter","year":"2004","journal-title":"Medicine and Science in Sports and Exercise"},{"issue":"1","key":"pone.0259624.ref037","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1123\/jab.21.1.31","article-title":"Relationships between ground reaction force impulse and kinematics of sprint-running acceleration","volume":"21","author":"JP Hunter","year":"2005","journal-title":"Journal of Applied Biomechanics"}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0259624","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,11,15]],"date-time":"2021-11-15T18:31:09Z","timestamp":1637001069000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0259624"}},"subtitle":[],"editor":[{"given":"Leonardo A.","family":"Peyr\u00e9-Tartaruga","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2021,11,15]]},"references-count":37,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2021,11,15]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0259624","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,11,15]]}}}