Fluid Balance During Physical Work in the Heat Is Not Modified by the Menstrual Cycle When Fluids Are Freely Available

Details

• Personal Author:
  Ables R ; Baker TB ; Bruinvels G ; Carter SJ ; Chapman RF ; Freemas JA ; Goss CS ; Martin, Bernard J. ; Mündel T ; Schlader ZJ
• Description:
  We tested the hypothesis that women will be more dehydrated during physical work in the heat in the early follicular phase (EF), compared to the late follicular (LF) and mid-luteal (ML) phases of the menstrual cycle when allowed free access to drink. Twelve healthy, eumenorrheic, unacclimated women (26 +/- 5 y) completed three trials (EF, LF, ML phases) involving 4 hours of exposure to 33.8 +/- 0.8 degrees C, 54 +/- 1% relative humidity. Each hour, participants walked on a treadmill for 30 min at a rate of metabolic heat production of 338 +/- 9 W. Participants drank a cool, flavor preferred non-caloric sport drink ad libitum. Nude body weight was measured pre- and post-exposure, and percent changes in body weight loss were interpreted as an index of changes in total body water. Total fluid intake and urine output were measured and sweat rate was estimated from changes in body mass corrected for fluid intake and urine output. Fluid intake was not different between phases (EF: 1609 +/- 919 mL; LF: 1902 +/- 799 mL; ML: 1913 +/- 671; P=0.202). Total urine output (P=0.543) nor sweat rate (P=0.907) differed between phases. Percent changes in body mass were not different between phases (EF: -0.5 +/- 0.9%; LF: -0.3 +/- 0.9%; ML: -0.3 +/- 0.7%; P=0.417). This study demonstrates that the normal hormonal fluctuations that occur throughout the menstrual cycle do not meaningfully alter fluid regulation during physical work in the heat. [Description provided by NIOSH]
• Subjects:
  Aging Body Weight Hot Temperature Humidity Occupational Health Safety Women
• Keywords:
  Age Groups Author Keywords: Exercise Body Weight Fluid Regulation Fluids Heat Exposure Heat Stress Menstrual Cycle Physiological Function
• ISSN:
  8750-7587
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Indiana ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  134
• Issue:
  6
• NIOSHTIC Number:
  nn:20067362
• Citation:
  J Appl Physiol 2023 Jun; 134(6):1376-1389
• Contact Point Address:
  Jessica A. Freemas, H.H. Morris Human Performance Laboratories, Department of Kinesiology, School of Public Health, Indiana University, Bloomington, IN, United States
• Email:
  jfreemas@iu.edu
• Federal Fiscal Year:
  2023
• Performing Organization:
  Indiana University, Bloomington
• Peer Reviewed:
  True
• Start Date:
  20190901
• Source Full Name:
  Journal of Applied Physiology
• End Date:
  20240831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:ddf4e5c0e45caadbc3d2c2ab4fecae3e14efdf16afef525a4adf198cb1e38a084e2d4104a439db5cae61f99ebd9b8d4c2e2451d69454449b2f818ba3d6d24927
• Download URL:
  https://stacks.cdc.gov/view/cdc/231428/cdc_231428_DS1.pdf
• File Type:
  [PDF - 1.38 MB ]