{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T22:23:49Z","timestamp":1790634229368,"version":"4.1.0"},"reference-count":60,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2019,6,18]],"date-time":"2019-06-18T00:00:00Z","timestamp":1560816000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002322","name":"Coordena\u00e7\u00e3o de Aperfei\u00e7oamento de Pessoal de N\u00edvel Superior","doi-asserted-by":"publisher","award":["001"],"award-info":[{"award-number":["001"]}],"id":[{"id":"10.13039\/501100002322","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medicina"],"abstract":"<jats:p>Background and objective: The assessment of physical fitness has become a necessary issue in epidemiological studies, since a reduction in fitness is directly associated with early mortality. Therefore, the development of simple, accurate, and inexpensive methods is necessary to measure physical fitness. This study aimed to determine the reliability and validity of the criteria and constructs of the International Fitness Scale (IFIS), Portuguese version, in Brazilian pediatric populations. Methods: A total of 190 children aged 3\u201310 years and 110 adolescents aged 11\u201317 years were enrolled in an observational study of reliability and validity. For reliability, the participants completed a questionnaire twice (with an interval of 15 days). To test the criterion validity, we analyzed the agreement between the questionnaire and physical tests (20-m shuttle run test, handgrip strength, standing long jump tests, 4 \u00d7 10-m shuttle run test, and back-saver sit and reach test), and the construct validity was estimated by agreement between the questionnaire and high blood pressure. The reliability was analyzed by kappa coefficients. The agreement between the testing and retesting of the questionnaire was evaluated by kappa coefficients. We applied a 2 \u00d7 2 table to estimate the specificity, sensitivity, and accuracy of the questionnaire. Results: The mean age of the children was 6.7 years (n = 190), and for the adolescents it was 14.6 years (n = 110). The questionnaire reliability showed an almost perfect score (\u03ba \u2265 0.93 in children and \u03ba \u2265 0.88 in adolescents). The questionnaire showed moderate criterion validity (\u03ba \u2265 0.40 in children and adolescents) as well as moderate construct validity (\u03ba \u2265 0.40) in the components of general conditioning, cardiorespiratory capacity, muscular strength, and speed\/agility in children and in the components of cardiorespiratory capacity, muscle strength, and speed\/agility in adolescents. The questionnaire was a sensitive method for measuring physical fitness. Conclusions: The Portuguese version of the IFIS is a reliable and valid method for measuring physical fitness in pediatric populations.<\/jats:p>","DOI":"10.3390\/medicina55060286","type":"journal-article","created":{"date-parts":[[2019,6,19]],"date-time":"2019-06-19T02:42:46Z","timestamp":1560912166000},"page":"286","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":31,"title":["Is Self-Reported Physical Fitness Useful for Estimating Fitness Levels in Children and Adolescents? A Reliability and Validity Study"],"prefix":"10.3390","volume":"55","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5763-435X","authenticated-orcid":false,"given":"Augusto C\u00e9sar Ferreira","family":"De Moraes","sequence":"first","affiliation":[{"name":"Department of Epidemiology; School of Public Health, University de S\u00e3o Paulo, 01246-904 S\u00e3o Paulo, Brazil"},{"name":"YCARE (Youth\/Child cArdiovascular Risk and Environmental) Research Group, Faculdade de Medicina, Universidade de S\u00e3o Paulo, 01246-903 S\u00e3o Paulo, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3221-2927","authenticated-orcid":false,"given":"Regina C\u00e9lia","family":"Vilanova-Campelo","sequence":"additional","affiliation":[{"name":"YCARE (Youth\/Child cArdiovascular Risk and Environmental) Research Group, Faculdade de Medicina, Universidade de S\u00e3o Paulo, 01246-903 S\u00e3o Paulo, Brazil"},{"name":"DOMEN (Metabolic Diseases, Exercise and Nutrition) Research Group, Department of Biophysical and Physiology, Federal University of Piaui, 64049-550 Teresina, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Francisco Leonardo","family":"Torres-Leal","sequence":"additional","affiliation":[{"name":"YCARE (Youth\/Child cArdiovascular Risk and Environmental) Research Group, Faculdade de Medicina, Universidade de S\u00e3o Paulo, 01246-903 S\u00e3o Paulo, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Her\u00e1clito Barbosa","family":"Carvalho","sequence":"additional","affiliation":[{"name":"Department of Epidemiology; School of Public Health, University de S\u00e3o Paulo, 01246-904 S\u00e3o Paulo, Brazil"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,6,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/sj.ijo.0803774","article-title":"Physical fitness in childhood and adolescence: A powerful marker of health","volume":"32","author":"Ortega","year":"2008","journal-title":"Int. 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