{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:35:11Z","timestamp":1760240111482,"version":"build-2065373602"},"reference-count":28,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2019,3,15]],"date-time":"2019-03-15T00:00:00Z","timestamp":1552608000000},"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 a Tecnologia","doi-asserted-by":"publisher","award":["SFRH\/ BD\/69407\/2010"],"award-info":[{"award-number":["SFRH\/ BD\/69407\/2010"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sports"],"abstract":"<jats:p>This study analyzed heart rate (HR) kinetics during the Yo-Yo Intermittent Endurance Test\u2014level 1 (Yo-Yo IE1) in children. At the middle of the school year, 107 boys (7\u201310 years old) performed the Yo-Yo IE1. Individual HR curves during the Yo-Yo IE1 were analyzed to detect an inflection point between an initial phase of fast rise in HR, and a second phase in which the rise of HR is slower. The 7th shuttle of the test was established as the inflection point. Engagement with extra-school sports practice was identified. Percentile groups (P1, P2 and P3) were created for body weight and physical fitness data composite (PFcomposite). Differences were found between the slopes of P1 and P3 on phase 1 for body weight (12.5 \u00b1 2.7 vs. 13.7 \u00b1 2.0 bpm\/shuttle; p = 0.033; d = 0.50) and PFcomposite (14.2 \u00b1 2.5 vs. 12.5 \u00b1 2.0 bpm\/shuttle; p = 0.015; d = 0.75). Time spent &gt;95% of peak HR was longer for the children engaged with extra-school sports practice (335 \u00b1 158 vs. 234 \u00b1 124 s; p &lt; 0.001; d = 0.71); differences were also detected for PFcomposite (P1, P2 and P3: 172 \u00b1 92, 270 \u00b1 109, and 360 \u00b1 157 s, respectively; p &lt; 0.05; d = 0.66\u20131.46). This study indicates that physical fitness and body weight influence HR kinetics during the Yo-Yo IE1 in pre-pubertal boys.<\/jats:p>","DOI":"10.3390\/sports7030065","type":"journal-article","created":{"date-parts":[[2019,3,18]],"date-time":"2019-03-18T04:06:55Z","timestamp":1552882015000},"page":"65","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Heart Rate Kinetics Response of Pre-Pubertal Children during the Yo-Yo Intermittent Endurance Test\u2014Level 1"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1301-1078","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Brito","sequence":"first","affiliation":[{"name":"Portugal Football School, Portuguese Football Federation, Oeiras 1495-433, Portugal"}]},{"given":"Lu\u00eds","family":"Fernandes","sequence":"additional","affiliation":[{"name":"Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto 4200-450, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9105-7421","authenticated-orcid":false,"given":"Ant\u00f3nio","family":"Rebelo","sequence":"additional","affiliation":[{"name":"Center of Research, Education, Innovation and Intervention in Sport, Faculty of Sport, University of Porto, Porto 4200-450, Portugal"}]},{"given":"Peter","family":"Krustrup","sequence":"additional","affiliation":[{"name":"Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense 5230, Denmark"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3930-7037","authenticated-orcid":false,"given":"Gustavo","family":"Silva","sequence":"additional","affiliation":[{"name":"Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University Institute of Maia, ISMAI, Maia 4475-690, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1829-4196","authenticated-orcid":false,"given":"Jos\u00e9","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Research Centre in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sport, University of Porto, Porto 4200-450, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2019,3,15]]},"reference":[{"key":"ref_1","unstructured":"Bangsbo, J. 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