{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T09:41:31Z","timestamp":1784799691653,"version":"3.55.0"},"reference-count":45,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2017,8,4]],"date-time":"2017-08-04T00:00:00Z","timestamp":1501804800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100003577","name":"American Dysautonomia Institute","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100003577","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Scandinavian Med Sci Sports"],"published-print":{"date-parts":[[2018,2]]},"abstract":"<jats:p>Females demonstrate less robust Frank\u2010Starling mechanism with respect to cardiac preload than males at rest. We asked whether this phenomenon would also affect cardiac performance during exercise. We hypothesized that stroke volume (<jats:styled-content style=\"fixed-case\">SV<\/jats:styled-content>) response to exercise would be <jats:italic>more<\/jats:italic> limited in deconditioned females such that cardiac output would be mainly rate dependent, compared with males. We conducted a chart audit of clinical exercise tests performed by adolescents with chronic fatigue. Oxygen uptake (<jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/sms12922-math-0001.png\" xlink:title=\"urn:x-wiley:09057188:media:sms12922:sms12922-math-0001\"\/>) was measured breath\u2010by\u2010breath at rest and during cycle ergometry, while cardiac output was measured by acetylene rebreathing at rest plus 2\u20103 subthreshold workloads. <jats:styled-content style=\"fixed-case\">SV<\/jats:styled-content> response was analyzed in two ways: after normalization for body surface area (<jats:styled-content style=\"fixed-case\">SV<\/jats:styled-content> index, <jats:styled-content style=\"fixed-case\">SVI<\/jats:styled-content>) and as percentage change from resting values. Among 304 adolescents (78% females) with chronic fatigue, 189 (80%) of 236 females and 52 (76%) of 68 males were deconditioned (peak<jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/sms12922-math-0002.png\" xlink:title=\"urn:x-wiley:09057188:media:sms12922:sms12922-math-0002\"\/>O<jats:sub>2<\/jats:sub> &lt;90% predicted). Heart rate trajectory during exercise was steeper for unfit than fit females, 70 vs 61\u00a0beat\u00b7min<jats:sup>\u22121<\/jats:sup> per L\u00b7min<jats:sup>\u22121<\/jats:sup> <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/sms12922-math-0003.png\" xlink:title=\"urn:x-wiley:09057188:media:sms12922:sms12922-math-0003\"\/>, (<jats:italic>P<\/jats:italic>=.003); but not for males, 47 vs 42\u00a0beat\u00b7min<jats:sup>\u22121<\/jats:sup> per L\u00b7min<jats:sup>\u22121<\/jats:sup> <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/sms12922-math-0004.png\" xlink:title=\"urn:x-wiley:09057188:media:sms12922:sms12922-math-0004\"\/> (<jats:italic>P<\/jats:italic>=.23). The highest measured <jats:styled-content style=\"fixed-case\">SVI<\/jats:styled-content> did not differ between unfit vs fit females (42.8 vs 41.5\u00a0mL\u00b7m<jats:sup>\u22122<\/jats:sup>, <jats:italic>P<\/jats:italic>=.39) while fit males showed larger <jats:styled-content style=\"fixed-case\">SV<\/jats:styled-content> during exercise than their unfit peers (highest <jats:styled-content style=\"fixed-case\">SVI<\/jats:styled-content> 55.9 vs 48.0\u00a0mL\u00b7m<jats:sup>\u22122<\/jats:sup>, <jats:italic>P<\/jats:italic>=.014). Both qualitative and quantitative sex differences exist in <jats:styled-content style=\"fixed-case\">SV<\/jats:styled-content> responses to exercise among chronically fatigued adolescents, suggesting volume loading may be more efficacious in girls.<\/jats:p>","DOI":"10.1111\/sms.12922","type":"journal-article","created":{"date-parts":[[2017,5,25]],"date-time":"2017-05-25T16:50:05Z","timestamp":1495731005000},"page":"524-531","source":"Crossref","is-referenced-by-count":4,"title":["Sex differences in fitness and cardiac function during exercise in adolescents with chronic fatigue"],"prefix":"10.1111","volume":"28","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8201-7591","authenticated-orcid":false,"given":"P. T.","family":"Pianosi","sequence":"first","affiliation":[{"name":"Department of Pediatric and Adolescent Medicine Mayo Clinic  Rochester MN USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E.","family":"Emerling","sequence":"additional","affiliation":[{"name":"Department of Pediatric and Adolescent Medicine Mayo Clinic  Rochester MN USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K. C.","family":"Mara","sequence":"additional","affiliation":[{"name":"Departments of Health Sciences Research Mayo Clinic  Rochester MN USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. L.","family":"Weaver","sequence":"additional","affiliation":[{"name":"Departments of Health Sciences Research Mayo Clinic  Rochester MN USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P. R.","family":"Fischer","sequence":"additional","affiliation":[{"name":"Department of Pediatric and Adolescent Medicine Mayo Clinic  Rochester MN USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2017,8,4]]},"reference":[{"key":"e_1_2_10_2_1","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1111\/j.1651-2227.1971.tb05693.x","article-title":"Cardiac output during exercise in pubertal boys","volume":"217","author":"Eriksson BO","year":"1971","journal-title":"Acta Paediatr Scand Suppl"},{"key":"e_1_2_10_3_1","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1152\/jappl.1971.31.3.348","article-title":"Cardiac output and arterial blood gases during exercise in pubertal boys","volume":"31","author":"Eriksson BO","year":"1971","journal-title":"J Appl 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