{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T12:41:42Z","timestamp":1779367302116,"version":"3.53.0"},"reference-count":22,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2021,7,9]],"date-time":"2021-07-09T00:00:00Z","timestamp":1625788800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Faculty of Education, Mie University","award":["(None)"],"award-info":[{"award-number":["(None)"]}]},{"name":"Institute of Health and Sports Science &amp; Medicine, Juntendo University","award":["(None)"],"award-info":[{"award-number":["(None)"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Although early sports specialization is associated with sports-related injuries, relevant quantitative studies on young non-elite athletes, the majority of sports participants, are scarce. We described sports specialization time points and the characteristics of sports-related injuries. Undergraduate students at a university in Japan (n = 830) recalled their history of sports participation from elementary to high school and sports-related injuries in a self-administered questionnaire. Of 570 valid respondents, 486 (85%) engaged in sports at least once. Significantly more respondents played multiple sports in upper elementary school (30%) than in other school categories (1\u201323%). In junior high and high schools, 90% and 99% played only one sport, respectively. Of the 486 respondents who played sports, 263 (54%) had experienced acute or overuse injuries. The proportion of injured participants significantly differed by school category: lower elementary school (4%), upper elementary school (21%), junior high (35%), and high school (41%). The proportions of acute or overuse injuries in males were higher than those in females. In conclusion, this study clarified a slight variation in sports items, particularly in junior high and high schools, which demonstrates 13 years as the age of beginning specialization in a single sport. More than half of the non-elite athletes experienced sports-related injuries. Injuries were frequently observed in males and those in junior high and high schools.<\/jats:p>","DOI":"10.3390\/ijerph18147369","type":"journal-article","created":{"date-parts":[[2021,7,12]],"date-time":"2021-07-12T00:23:36Z","timestamp":1626049416000},"page":"7369","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Sports Specialization and Sports-Related Injuries in Japanese School-Aged Children and Adolescents: A Retrospective Descriptive Study"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4852-1265","authenticated-orcid":false,"given":"Ryosuke","family":"Shigematsu","sequence":"first","affiliation":[{"name":"Faculty of Education, Mie University, Tsu 514-8507, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shuta","family":"Katoh","sequence":"additional","affiliation":[{"name":"Course for Health and Physical Education, Faculty of Education, Mie University, Tsu 514-8507, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2089-0886","authenticated-orcid":false,"given":"Koya","family":"Suzuki","sequence":"additional","affiliation":[{"name":"Department of Sports Science, Juntendo University, Chiba 270-1695, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0888-4440","authenticated-orcid":false,"given":"Yoshio","family":"Nakata","sequence":"additional","affiliation":[{"name":"Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba 305-8577, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8120-6163","authenticated-orcid":false,"given":"Hiroyuki","family":"Sasai","sequence":"additional","affiliation":[{"name":"Research Team for Promoting Independence and Mental Health, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,9]]},"reference":[{"key":"ref_1","unstructured":"(2021, May 26). 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