{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,11]],"date-time":"2026-08-11T21:28:01Z","timestamp":1786483681823,"version":"build-2736575974"},"reference-count":40,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2026,3,8]],"date-time":"2026-03-08T00:00:00Z","timestamp":1772928000000},"content-version":"vor","delay-in-days":7,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,3,1]],"date-time":"2026-03-01T00:00:00Z","timestamp":1772323200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Scandinavian Med Sci Sports"],"published-print":{"date-parts":[[2026,3]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Sex differences in competitive running performance are well documented in adults but understudied in prepubertal children. Prior studies have often focused on elite performers or record holders, potentially neglecting trends across the full competitive field, and some have reported minimal sex\u2010based differences before age 11, leaving the existence of prepubertal performance differences unclear. This study examined whether sex\u2010based differences in running performance are present among all competitors in the 8\u2010and\u2010under and 9\u201310\u2010year\u2010old age groups at USA Track &amp; Field (USATF) Regional Junior Olympic Championships. All official race times from the 100\u2009m, 200\u2009m, 400\u2009m, 800\u2009m, and 1500\u2009m events were collected from all 15 USATF Regional Championships held in 2022\u20132024. Preliminary and final race times were compared by sex using two\u2010way ANOVA (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009&lt;\u20090.05), and performance differences were further evaluated across the 95th, 90th, 75th, 50th, 25th, and 10th percentiles. In the 8\u2010and\u2010under group, males (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u20092696 race times) ran 3.8%\u20135.9% faster than females (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u20092710) across all distances (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009&lt;\u20090.001; Hedges'\n                    <jats:italic>g<\/jats:italic>\n                    \u2009=\u20090.39\u20130.63). In the 9\u201310\u2010year\u2010old group, males (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u20093265) ran 3.4%\u20135.5% faster than females (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u20093182) across all distances (\n                    <jats:italic>p<\/jats:italic>\n                    \u2009&lt;\u20090.001; Hedges'\n                    <jats:italic>g<\/jats:italic>\n                    \u2009=\u20090.31\u20130.52). The fastest individual males outperformed the fastest individual females by 1.8%\u201311.6% across events and age groups. Across percentiles, males ran on average 4.4%\u2009\u00b1\u20091.2% faster than females. These findings demonstrate that sex\u2010based differences in running performance are evident by ages 8\u201310\u2009years and extend across the full spectrum of competitors, not solely elite youth athletes.\n                  <\/jats:p>","DOI":"10.1111\/sms.70251","type":"journal-article","created":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T05:01:21Z","timestamp":1773032481000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Sex Differences in Running Performance Among 8\u2010and\u2010Under and 9\u201310\u2010Year\u2010Old Children in\n                    <scp>US<\/scp>\n                    Regional Track Championships"],"prefix":"10.1111","volume":"36","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9928-217X","authenticated-orcid":false,"given":"Gregory A.","family":"Brown","sequence":"first","affiliation":[{"name":"Physical Activity and Wellness Laboratory, Department of Kinesiology and Sport Sciences University of Nebraska at Kearney  Kearney Nebraska USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2285-8361","authenticated-orcid":false,"given":"Brandon S.","family":"Shaw","sequence":"additional","affiliation":[{"name":"School of Sport, Rehabilitation and Exercise Sciences University of Essex  Colchester UK"},{"name":"Division of Public Health University of the Free State  Bloemfontein South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8400-8234","authenticated-orcid":false,"given":"Ina","family":"Shaw","sequence":"additional","affiliation":[{"name":"School of Sport, Rehabilitation and Exercise Sciences University of Essex  Colchester UK"},{"name":"Division of Public Health University of the Free State  Bloemfontein South Africa"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,3,8]]},"reference":[{"key":"e_1_2_11_2_1","doi-asserted-by":"publisher","DOI":"10.1210\/endrev\/bnaa034"},{"key":"e_1_2_11_3_1","doi-asserted-by":"publisher","DOI":"10.1249\/MSS.0000000000003300"},{"key":"e_1_2_11_4_1","doi-asserted-by":"publisher","DOI":"10.1136\/bjsports\u20102022\u2010106386"},{"key":"e_1_2_11_5_1","doi-asserted-by":"publisher","DOI":"10.1097\/CORR.0000000000002679"},{"key":"e_1_2_11_6_1","doi-asserted-by":"publisher","DOI":"10.1113\/JP284198"},{"key":"e_1_2_11_7_1","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00615.2024"},{"key":"e_1_2_11_8_1","doi-asserted-by":"publisher","DOI":"10.1111\/cen.13350"},{"key":"e_1_2_11_9_1","doi-asserted-by":"publisher","DOI":"10.1210\/jendso\/bvac035"},{"key":"e_1_2_11_10_1","doi-asserted-by":"publisher","DOI":"10.3390\/sports12120347"},{"key":"e_1_2_11_11_1","doi-asserted-by":"publisher","DOI":"10.1249\/MSS.0000000000003423"},{"key":"e_1_2_11_12_1","doi-asserted-by":"publisher","DOI":"10.1002\/ejsc.12075"},{"key":"e_1_2_11_13_1","doi-asserted-by":"publisher","DOI":"10.1002\/ejsc.12241"},{"key":"e_1_2_11_14_1","doi-asserted-by":"publisher","DOI":"10.1002\/ejsc.12237"},{"key":"e_1_2_11_15_1","doi-asserted-by":"publisher","DOI":"10.1249\/esm.0000000000000051"},{"key":"e_1_2_11_16_1","doi-asserted-by":"publisher","DOI":"10.1249\/MSS.0000000000003681"},{"key":"e_1_2_11_17_1","doi-asserted-by":"publisher","DOI":"10.1002\/ejsc.70008"},{"key":"e_1_2_11_18_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ecl.2024.01.005"},{"key":"e_1_2_11_19_1","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2020.565519"},{"key":"e_1_2_11_20_1","volume-title":"USA Track & Field|Associations","author":"USA Track & Field","year":"2026"},{"key":"e_1_2_11_21_1","volume-title":"USA Track & Field|Rule Books","author":"USA Track & Field","year":"2026"},{"key":"e_1_2_11_22_1","doi-asserted-by":"publisher","DOI":"10.3758\/BF03193146"},{"key":"e_1_2_11_23_1","first-page":"84","volume-title":"AAPHER Youth Fitness Test Manual","author":"Hunsicker P. 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