{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:32:48Z","timestamp":1760239968834,"version":"build-2065373602"},"reference-count":17,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2019,2,22]],"date-time":"2019-02-22T00:00:00Z","timestamp":1550793600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100011740","name":"Bundesamt f\u00fcr Sport","doi-asserted-by":"publisher","award":["15-01; VM10052"],"award-info":[{"award-number":["15-01; VM10052"]}],"id":[{"id":"10.13039\/501100011740","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Lausanne Orthopaedic Research Foundation","award":["n\/a"],"award-info":[{"award-number":["n\/a"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In alpine skiing, intermediate times are usually measured with photocells. However, for practical reasons, the number of intermediate cells is limited to three\u2013four, making a detailed timing analysis difficult. In this paper, we propose and validate a magnet-based timing system allowing for the measurement of intermediate times at each gate. Specially designed magnets were placed at each gate and the athletes wore small magnetometers on their lower back to measure the instantaneous magnetic field. The athlete\u2019s gate crossings caused peaks in the measured signal which could then be related to the precise instants of gate crossings. The system was validated against photocells placed at four gates of a slalom skiing course. Eight athletes skied the course twice and one run per athlete was included in the validation study. The 95% error intervals for gate-to-gate timing and section times were below 0.025 s. Each athlete\u2019s gate-to-gate times were compared to the group\u2019s average gate-to-gate times, revealing small performance differences that would otherwise be difficult to measure with a traditional photocell-based system. The system could be used to identify the effect of tactical choices and athlete specific skiing skills on performance and could allow a more efficient and athlete-specific performance analysis and feedback.<\/jats:p>","DOI":"10.3390\/s19040940","type":"journal-article","created":{"date-parts":[[2019,2,22]],"date-time":"2019-02-22T11:26:14Z","timestamp":1550834774000},"page":"940","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["A Magnet-Based Timing System to Detect Gate Crossings in Alpine Ski Racing"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9322-0621","authenticated-orcid":false,"given":"Benedikt","family":"Fasel","sequence":"first","affiliation":[{"name":"Archinisis GmbH, 1700 Fribourg, Switzerland"},{"name":"Laboratory of Movement Analysis and Measurement, Ecole Polytechnique F\u00e9d\u00e9rale de Lausanne, 1015 Lausanne, Switzerland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0353-1021","authenticated-orcid":false,"given":"J\u00f6rg","family":"Sp\u00f6rri","sequence":"additional","affiliation":[{"name":"Department of Orthopedics, Balgrist University Hospital, University of Zurich, 8008 Zurich, Switzerland"},{"name":"Department of Sport Science and Kinesiology, University of Salzburg, 5400 Hallein-Rif, Austria"}]},{"given":"Josef","family":"Kr\u00f6ll","sequence":"additional","affiliation":[{"name":"Department of Sport Science and Kinesiology, University of Salzburg, 5400 Hallein-Rif, Austria"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3857-2584","authenticated-orcid":false,"given":"Erich","family":"M\u00fcller","sequence":"additional","affiliation":[{"name":"Department of Sport Science and Kinesiology, University of Salzburg, 5400 Hallein-Rif, Austria"}]},{"given":"Kamiar","family":"Aminian","sequence":"additional","affiliation":[{"name":"Laboratory of Movement Analysis and Measurement, Ecole Polytechnique F\u00e9d\u00e9rale de Lausanne, 1015 Lausanne, Switzerland"}]}],"member":"1968","published-online":{"date-parts":[[2019,2,22]]},"reference":[{"key":"ref_1","unstructured":"(2016). International Ski Federation The International Ski Competition Rules (ICR)\u2014Book IV: Joint Regulations for Alpine Skiing, International Ski Federation FIS."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"647","DOI":"10.1260\/1747-9541.7.4.647","article-title":"Turn characteristics of a top world class athlete in giant slalom: A case study assessing current performance prediction concepts","volume":"7","author":"Schwameder","year":"2012","journal-title":"Int. J. Sports Sci. Coach."},{"key":"ref_3","first-page":"59","article-title":"Relations between different technical and tactical approaches and overall time at Men\u2019s world cup giant slalom races","volume":"12","author":"Supej","year":"2006","journal-title":"Kinesiol. Slov."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1136\/bjsports-2015-095465","article-title":"Sidecut radius and kinetic energy: Equipment designed to reduce risk of severe traumatic knee injuries in alpine giant slalom ski racing","volume":"50","author":"Gilgien","year":"2016","journal-title":"Br. J. Sports Med."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"e72","DOI":"10.1111\/j.1600-0838.2010.01159.x","article-title":"Mechanical parameters as predictors of performance in alpine World Cup slalom racing","volume":"21","author":"Supej","year":"2011","journal-title":"Scand. J. Med. Sci. Sports"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1063","DOI":"10.1080\/02640414.2012.690073","article-title":"Quantifying instantaneous performance in alpine ski racing","volume":"30","author":"Federolf","year":"2012","journal-title":"J. Sports Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"519","DOI":"10.1007\/s40279-013-0132-z","article-title":"Biomechanical factors influencing the performance of elite alpine ski racers","volume":"44","author":"Supej","year":"2014","journal-title":"Sports Med."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e38","DOI":"10.1111\/sms.12007","article-title":"Aerodynamic drag is not the major determinant of performance during giant slalom skiing at the elite level","volume":"23","author":"Supej","year":"2013","journal-title":"Scand. J. Med. Sci. Sports"},{"key":"ref_9","first-page":"11","article-title":"STEALTHTM\u2014A GNSS-based advanced device to train Canadian olympic skiers","volume":"64","author":"Lachapelle","year":"2010","journal-title":"Geomatica"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1080\/02701367.2011.10599772","article-title":"A new time measurement method using a high-end global navigation satellite system to analyze alpine skiing","volume":"82","author":"Supej","year":"2011","journal-title":"Res. Q. Exerc. Sport"},{"key":"ref_11","first-page":"14","article-title":"The use of a high-end global navigation satellite system in a 100 m sprint","volume":"16","author":"Supej","year":"2010","journal-title":"Kinesiol. Slov."},{"key":"ref_12","unstructured":"Chow, T.L. (2006). Introduction to Electromagnetic Theory: A Modern Perspective, Jones and Bartlett Publishers."},{"key":"ref_13","unstructured":"Fasel, B., Sp\u00f6rri, J., Kr\u00f6ll, J., and Aminian, K. (2016, January 10\u201315). Alpine ski racing gate crossing detection using magnetometers. Proceedings of the Abstract Book of the 7th International Congress on Science and Skiing, St. Christoph\/Arlberg, Austria."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.sna.2009.10.008","article-title":"Calibration methods for inertial and magnetic sensors","volume":"156","author":"Bonnet","year":"2009","journal-title":"Sens. Actuators A Phys."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"612","DOI":"10.1049\/el:20060124","article-title":"Quaternion-based fusion of gyroscopes and accelerometers to improve 3D angle measurement","volume":"42","author":"Favre","year":"2006","journal-title":"Electron. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1111\/j.1600-0838.2007.00745.x","article-title":"Impact of skier actions on the gliding times in alpine skiing","volume":"18","author":"Federolf","year":"2008","journal-title":"Scand. J. Med. Sci. Sports"},{"key":"ref_17","unstructured":"Reid, R.C. (2010). A Kinematic and Kinetic Study of Alpine Skiing Technique in Slalom. [Ph.D. Thesis, Norwegian School of Sport Sciences]."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/4\/940\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:34:16Z","timestamp":1760186056000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/4\/940"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,2,22]]},"references-count":17,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2019,2]]}},"alternative-id":["s19040940"],"URL":"https:\/\/doi.org\/10.3390\/s19040940","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2019,2,22]]}}}