Effects of mild hypohydration on cooling during cold-water immersion following exertional hyperthermia

• Published in: European journal of applied physiology 2016-04, Vol.116 (4), p.687-695
• Main Authors: Butts, Cory L., Luhring, Katherine E., Smith, Cody R., Tucker, Matthew A., Moyen, Nicole E., Ganio, Matthew S., McDermott, Brendon P.
• Format: Article
• Language: English
• Subjects: Adult; Biomedical and Life Sciences; Biomedicine; Blood; Body fat; Body Temperature - physiology; Cold; Cold Temperature; Cooling; Exercise; Female; Fever; Heart rate; Heat; Human Physiology; Humans; Hydration; Hyperthermia; Hyperthermia, Induced; Hypothermia, Induced; Ice; Immersion; Male; Occupational Medicine/Industrial Medicine; Original Article; Skin; Sports Medicine; Temperature; Water-Electrolyte Balance - physiology
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-016-3329-7

Purpose We investigated the effects of mild hypohydration compared to euhydration on the cooling efficacy of cold-water immersion (CWI). Methods Fourteen participants (eight male, six female; age 26 ± 5 years; ht 1.77 ± 0.08 m; wt 72.2 ± 8.8 kg; 20.6 ± 7.4 % body fat) completed one euhydrated (EU) trial followed by one hypohydrated trial (HY; via 24 h fluid restriction) in an environmental chamber (33.6 ± 0.9 °C, 55.8 ± 1.7 % RH). Volitional exercise was performed in a manner that matched end-exercise rectal temperature ( T re ) through repeating exercise mode and intensity. Participants were then immersed in ice water (2.0 ± 0.8 °C) until T re reached 38.1 °C or for a maximum of 15 min. T re , heart rate (HR), skin blood flux (SBF) and mean skin temperature ( T sk ) were monitored continuously during cooling. Results Pre-cooling body mass was decreased in the HY trial (−2.66 ± 1.23 % body mass) and maintained in the EU trial (−0.66 ± 0.44 %) compared to baseline mass ( P   0.05), however, all variables significantly decreased with immersion independent of hydration status ( P