{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T00:45:35Z","timestamp":1790210735338,"version":"4.1.0"},"reference-count":41,"publisher":"American Physiological Society","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Applied Physiology"],"published-print":{"date-parts":[[2007,8]]},"abstract":"<jats:p> This study was conducted during the high-hormone phase of both natural and oral contraceptive pill (OCP)-mediated menstrual cycles to determine whether preexercise ingestion of a concentrated sodium beverage would increase plasma volume (PV), reduce physiological strain, and aid endurance of moderately trained women cycling in warm conditions. Thirteen trained cyclists [peak O<jats:sub>2<\/jats:sub> uptake 52 ml\u00b7kg<jats:sup>\u22121<\/jats:sup>\u00b7min<jats:sup>\u22121<\/jats:sup> (SD 2), age 26 yr (SD 6), weight 60.8 kg (SD 5)] who were oral contraceptive users ( n = 6) or not ( n = 7) completed this double-blind, crossover experiment. Cyclists ingested a concentrated-sodium (High Na<jats:sup>+<\/jats:sup>: 164 mmol Na<jats:sup>+<\/jats:sup>\/l) or low-sodium (Low Na<jats:sup>+<\/jats:sup>: 10 mmol Na<jats:sup>+<\/jats:sup>\/l) beverage (10 ml\/kg) before cycling to exhaustion at 70% Peak O<jats:sub>2<\/jats:sub> uptake in warm conditions (32\u00b0C, 50% relative humidity, air velocity 4.5 m\/s). Beverage (\u223c628 ml) was ingested in seven portions across 60 min beginning 105 min before exercise, with no additional fluid given until the end of the trial. Trials were separated by one to two menstrual cycles. High Na<jats:sup>+<\/jats:sup> increased PV (calculated from hematocrit and hemoglobin concentration) before exercise, whereas Low Na<jats:sup>+<\/jats:sup> did not [\u22124.4 (SD 1.1) vs. \u22121.9% (SD 1.3); 95% confidence interval: for the difference 5.20, 6.92; P &lt; 0.0001], and it involved greater time to exhaustion [98.8 (SD 25.6) vs. 78.7 (SD 24.6) min; 95% confidence interval: 13.3, 26.8; P &lt; 0.0001]. Core temperature rose more quickly with Low Na<jats:sup>+<\/jats:sup> [1.6\u00b0C\/h (SD 0.2)] than High Na<jats:sup>+<\/jats:sup> [1.2\u00b0C\/h (SD 0.2); P = 0.04]. Plasma [AVP], [Na<jats:sup>+<\/jats:sup>] concentration, and osmolality, and urine volume, [Na<jats:sup>+<\/jats:sup>], and osmolality decreased with sodium loading ( P &lt; 0.05) independent of pill usage. Thus preexercise ingestion of a concentrated sodium beverage increased PV, reduced thermoregulatory strain, and increased exercise capacity for women in the high-hormone phase of natural and oral contraceptive pill-mediated menstrual cycles, in warm conditions. <\/jats:p>","DOI":"10.1152\/japplphysiol.01203.2006","type":"journal-article","created":{"date-parts":[[2007,4,26]],"date-time":"2007-04-26T21:03:45Z","timestamp":1177621425000},"page":"534-541","source":"Crossref","is-referenced-by-count":66,"title":["Preexercise sodium loading aids fluid balance and endurance for women exercising in the heat"],"prefix":"10.1152","volume":"103","author":[{"given":"Stacy T.","family":"Sims","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nancy J.","family":"Rehrer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melanie L.","family":"Bell","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James D.","family":"Cotter","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"R1","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00154.2006"},{"key":"R2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.1992.tb14507.x"},{"key":"R3","unstructured":"Bungo MW, Charles JB, Johnson PC. Cardiovascular deconditioning during spaceflight and the use of saline as a countermeasure to orthostatic intolerance. Aviat Space Environ Med 56: 985\u2013990, 1985."},{"key":"R4","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1997.83.6.2012"},{"key":"R5","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1999.87.1.381"},{"key":"R6","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1999.87.5.1719"},{"key":"R7","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1981.50.1.123"},{"key":"R8","unstructured":"Cunningham DJ, Cabanac M. Evidence form behavioral thermoregulatory responses of a shift in set-point temperature related to the menstrual cycle. J Physiol (Paris) 63: 236\u2013238, 1971."},{"key":"R9","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1974.37.2.247"},{"key":"R10","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1988.65.2.519"},{"key":"R11","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1984.57.6.1688"},{"key":"R12","doi-asserted-by":"publisher","DOI":"10.1002\/j.1552-4604.1991.tb03643.x"},{"key":"R13","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1971.30.6.847"},{"key":"R14","unstructured":"Greenleaf JE, Jackson CG, Geelen G, Keil LC, Hinghofer-Szalkay H, Whittam JH. Plasma volume expansion with oral fluids in hypohydrated men at rest and during exercise. Aviat Space Environ Med 69: 837\u2013844, 1998."},{"key":"R15","unstructured":"Greenleaf JE, Looft-Wilson R, Wisherd JL, McKenzie MA, Jensen CD, Whittam JH. Pre-exercise hypervolemia and cycle ergometer endurance in men. Biol Sport 14: 103\u2013114, 1997."},{"key":"R16","unstructured":"Greenleaf JE, Looft-Wilson R, Wisherd JL, Jackson CGR, Fung PP, Ertl AC, Barnes PR, Jensen CD, Whittam JH. Hypervolemia in men from fluid ingestion at rest and during exercise. Aviat Space Environ Med 69: 374\u2013386, 1998."},{"key":"R17","doi-asserted-by":"publisher","DOI":"10.1210\/jcem.87.4.8406"},{"key":"R18","doi-asserted-by":"publisher","DOI":"10.1249\/01.MSS.0000150075.81511.FE"},{"key":"R19","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.00027.2004"},{"key":"R20","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.2001.280.3.R807"},{"key":"R21","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1997.82.4.1079"},{"key":"R22","doi-asserted-by":"publisher","DOI":"10.1111\/j.1749-6632.1997.tb51694.x"},{"key":"R23","doi-asserted-by":"publisher","DOI":"10.1136\/bjsm.31.3.175"},{"key":"R24","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.101.8.862"},{"key":"R25","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1992.73.4.1340"},{"key":"R26","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.1998.275.1.R129"},{"key":"R27","doi-asserted-by":"publisher","DOI":"10.1016\/S0079-6123(08)62049-X"},{"key":"R28","doi-asserted-by":"publisher","DOI":"10.1016\/0002-9378(87)90364-4"},{"key":"R29","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1992.72.2.543"},{"key":"R30","doi-asserted-by":"publisher","DOI":"10.1249\/01.MSS.0000106181.52102.99"},{"key":"R31","doi-asserted-by":"publisher","DOI":"10.1152\/ajpendo.00192.2002"},{"key":"R32","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.2001.281.4.R1319"},{"key":"R33","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.2000.88.5.1643"},{"key":"R34","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1999.87.3.1016"},{"key":"R35","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.01032.2003"},{"key":"R36","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00031.2005"},{"key":"R37","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.2002.282.1.H264"},{"key":"R38","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1999.86.1.22"},{"key":"R39","doi-asserted-by":"publisher","DOI":"10.1007\/BF00417979"},{"key":"R40","doi-asserted-by":"publisher","DOI":"10.1249\/01.mss.0000241639.97972.4a"},{"key":"R41","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1964.19.3.531"}],"container-title":["Journal of Applied Physiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.physiology.org\/doi\/pdf\/10.1152\/japplphysiol.01203.2006","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,9,8]],"date-time":"2019-09-08T17:02:29Z","timestamp":1567962149000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.physiology.org\/doi\/10.1152\/japplphysiol.01203.2006"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2007,8]]},"references-count":41,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2007,8]]}},"alternative-id":["10.1152\/japplphysiol.01203.2006"],"URL":"https:\/\/doi.org\/10.1152\/japplphysiol.01203.2006","relation":{},"ISSN":["8750-7587","1522-1601"],"issn-type":[{"value":"8750-7587","type":"print"},{"value":"1522-1601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2007,8]]}}}