{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,18]],"date-time":"2026-04-18T02:02:42Z","timestamp":1776477762501,"version":"3.51.2"},"reference-count":37,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,5,31]],"date-time":"2022-05-31T00:00:00Z","timestamp":1653955200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia","doi-asserted-by":"publisher","award":["2020.06799.BD"],"award-info":[{"award-number":["2020.06799.BD"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Backstroke swimming, a cyclic and continuous movement, displays a repeating structure due to the repeated action of the limb, presenting similar (but not identical) cycles. Some variability is generated by instabilities, but this may play a functional role in the human performance, allowing individual adaptations to constraints. The current study examined the role of velocity variability in backstroke performance, hypothesizing that this variable is associated with swimmers\u2019 performance. Sixteen elite and fifteen good-level swimmers were video recorded in the sagittal plane when performing 25 m backstroke at maximal intensity in order to determine hip velocity and mean velocity, stroke rate, stroke length and indexes of coordination\/synchronization. Lyapunov maximal exponent and sample entropy were also calculated for successive cycles. The elite swimmers\u2019 performances were more unstable (0.1742 \u00b1 0.1131 versus 0.0831 \u00b1 0.0042, p &lt; 0.001) and complex (0.9222 \u00b1 0.4559 versus 0.3821 \u00b1 0.3096, p &lt; 0.001) than their good-level counterparts, but intracycle velocity variation did not differ (11.98 \u00b1 3.47 versus 12.03 \u00b1 3.16%, p &gt; 0.05). Direct relationships were observed between mean velocity and stability (r = 0.40, p = 0.03), as well as with complexity (r = 0.53, p = 0.002), with intracycle velocity variation and complexity also being related (r = 0.38, p = 0.04). Backstroke performance is associated with velocity variability, with elite swimmers being able to control it through several adaptations, overcoming the high drag and inertia.<\/jats:p>","DOI":"10.3390\/ijerph19116744","type":"journal-article","created":{"date-parts":[[2022,6,1]],"date-time":"2022-06-01T03:33:18Z","timestamp":1654054398000},"page":"6744","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Velocity Variability and Performance in Backstroke in Elite and Good-Level Swimmers"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5720-1554","authenticated-orcid":false,"given":"Al\u00e9xia","family":"Fernandes","sequence":"first","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport and Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4382-0159","authenticated-orcid":false,"given":"M\u00e1rcio","family":"Goethel","sequence":"additional","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport and Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2351-3047","authenticated-orcid":false,"given":"Daniel A.","family":"Marinho","sequence":"additional","affiliation":[{"name":"Department of Sports Sciences, University of Beira Interior, 6201-001 Covilh\u00e3, Portugal"},{"name":"Research Centre in Sports, Health and Human Development (CIDESD), 6201-001 Covilh\u00e3, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6293-5571","authenticated-orcid":false,"given":"Bruno","family":"Mez\u00eancio","sequence":"additional","affiliation":[{"name":"Biomechanics Laboratory, School of Physical Education and Sport, University of S\u00e3o Paulo, S\u00e3o Paulo 05508-030, Brazil"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4109-2939","authenticated-orcid":false,"given":"Jo\u00e3o Paulo","family":"Vilas-Boas","sequence":"additional","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport and Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5811-0443","authenticated-orcid":false,"given":"Ricardo Jorge","family":"Fernandes","sequence":"additional","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport and Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1080\/14763141.2012.738700","article-title":"Movement variability and skills monitoring in sports","volume":"12","author":"Preatoni","year":"2013","journal-title":"Sports Biomech."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Fernandes, A., Mezencio, B., Soares, S., Carvalho, D., Silva, A., Vilas-Boas, J.P., and Fernandes, R.J. 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