{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T15:55:42Z","timestamp":1790610942855,"version":"4.1.0"},"reference-count":26,"publisher":"American Physiological Society","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Applied Physiology"],"published-print":{"date-parts":[[2005,2]]},"abstract":"<jats:p> Long-term head-down-tilt bed rest (HDT) causes cardiovascular deconditioning, attributed to reflex dysfunctions, plasma volume reduction, or cardiac impairments. Our objective with the present study was to evaluate the functional importance and relative contribution of these during rest and exercise in supine and upright postures. We studied six subjects before (baseline), during [ days 60 (D60) and 113 (D113)], and after [recovery days 0 (R0), 3 (R3), and 15 (R15)] 120 days of \u22126\u00b0 HDT. We determined cardiac output, stroke volume (SV), mean arterial pressure, and heart rate during rest and exercise in supine and upright postures. Cardiac output and SV decreased significantly in all four conditions, but the time courses differed for rest and exercise. Upright resting SV was decreased by 24 \u00b1 9% at D60 compared with baseline but had recovered already at R3. Supine exercise SV decreased more slowly (by 5 \u00b1 8% at D60 and by 18 \u00b1 4% at D113) and recovered more slowly after HDT termination. Steady-state mean arterial pressure showed no changes. Heart rate had increased by 18 \u00b1 4% at D60 and had recovered partially at R3. Our data indicate that long-term HDT causes both a rapid, preload-dependent reduction in SV, most evident during rest in the upright position, and a more slowly developing cardiac dysfunction, most evident during supine exercise. However, the ability to maintain blood pressure and to perform sustained low levels of dynamic exercise is not influenced by HDT. <\/jats:p>","DOI":"10.1152\/japplphysiol.01332.2003","type":"journal-article","created":{"date-parts":[[2004,10,22]],"date-time":"2004-10-22T20:15:41Z","timestamp":1098476141000},"page":"648-654","source":"Crossref","is-referenced-by-count":59,"title":["Long-term bed rest-induced reductions in stroke volume during rest and exercise: cardiac dysfunction vs. volume depletion"],"prefix":"10.1152","volume":"98","author":[{"given":"Jonas","family":"Spaak","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"St\u00e9phanie","family":"Montmerle","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Patrik","family":"Sundblad","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dag","family":"Linnarsson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"R1","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1996.81.1.98"},{"key":"R2","doi-asserted-by":"publisher","DOI":"10.1007\/BF00635629"},{"key":"R3","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.65.1.134"},{"key":"R4","unstructured":"Convertino VA. Exercise and adaptation to microgravity environments. In: Handbook of Physiology. Environmental Physiology. Bethesda, MD: Am. Physiol. Soc., sect. 4, vol. II, chapt. 36, p. 815\u2013844, 1996."},{"key":"R5","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1990.68.4.1458"},{"key":"R6","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1994.266.6.R1962"},{"key":"R7","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1997.273.1.R93"},{"key":"R8","unstructured":"Ebert TJ, Smith JJ, Barney JA, Merrill DC, and Smith GK. The use of thoracic impedance for determining thoracic blood volume changes in man. Aviat Space Environ Med 57: 49\u201353, 1986."},{"key":"R9","doi-asserted-by":"publisher","DOI":"10.1111\/j.1748-1716.1971.tb04887.x"},{"key":"R10","unstructured":"Fortney SM, Hyatt KH, Davis JE, and Vogel JM. Changes in body fluid compartments during a 28-day bed rest. Aviat Space Environ Med 62: 97\u2013104, 1991."},{"key":"R11","unstructured":"Fortney SM, Schneider VS, and Greenleaf JE. The physiology of bed rest. In: Handbook of Physiology. Environmental Physiology. Bethesda, MD: Am. Physiol. Soc., sect. 4, vol. I, chapt. 39, p. 889\u2013939, 1996."},{"key":"R12","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1992.73.2.S94"},{"key":"R13","doi-asserted-by":"publisher","DOI":"10.1136\/jim-52-02-21"},{"key":"R14","unstructured":"Guell A, Braak L, Le Traon AP, and Gharib C. Cardiovascular adaptation during simulated microgravity: lower body negative pressure to counter orthostatic hypotension. Aviat Space Environ Med 62: 331\u2013335, 1991."},{"key":"R15","doi-asserted-by":"publisher","DOI":"10.1093\/cvr\/24.3.214"},{"key":"R16","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2281.1997.02626.x"},{"key":"R17","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1998.275.4.R1343"},{"key":"R18","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.96.2.517"},{"key":"R19","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2001.91.2.645"},{"key":"R20","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.103.14.1851"},{"key":"R21","unstructured":"Rowell LB, O\u2019Leary DS, and Kellogg JDL. Integration of cardiovascular control systems in dynamic exercise. In: Handbook of Physiology. Exercise: Regulation and Integration of Multiple Systems. Bethesda, MD: Am. Physiol. Soc. 1996, sect. 12, chapt. 17, p. 770\u2013840."},{"key":"R22","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.38.5S7.VII-1"},{"key":"R23","doi-asserted-by":"publisher","DOI":"10.1007\/s004210000258"},{"key":"R24","doi-asserted-by":"publisher","DOI":"10.1007\/s004210000209"},{"key":"R25","unstructured":"Triebwasser JH, Johnson RL, Burpo RP, Campbell JC, Reardon WC, and Blomqvist CG. Noninvasive determination of cardiac output by a modified acetylene rebreathing procedure utilizing mass spectrometer measurements. Aviat Space Environ Med 48: 203\u2013209, 1977."},{"key":"R26","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2001.91.1.417"}],"container-title":["Journal of Applied Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.physiology.org\/doi\/pdf\/10.1152\/japplphysiol.01332.2003","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,9,8]],"date-time":"2019-09-08T16:14:02Z","timestamp":1567959242000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.physiology.org\/doi\/10.1152\/japplphysiol.01332.2003"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2005,2]]},"references-count":26,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2005,2]]}},"alternative-id":["10.1152\/japplphysiol.01332.2003"],"URL":"https:\/\/doi.org\/10.1152\/japplphysiol.01332.2003","relation":{},"ISSN":["8750-7587","1522-1601"],"issn-type":[{"value":"8750-7587","type":"print"},{"value":"1522-1601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2005,2]]}}}