Use of Biomarkers to Optimize Heat Acclimation in Women
Abstract
These experiments determined if estrogen (E2) supplementation in (a) menstruating young women during the follicular phase of their menstrual cycle, or (b) ovariectomized female rats would promote heat loss in women and enhance thermotolerance in animals. Women 11 CONTROL (P), 10 experimental (e) performed cycle exercise at 60% VO2 max in a cool (25 deg C) room for 20 min. Neither sweating threshold (36.97+ or -0.15 deg C in P vs 36.9+ or -0.22 deg C in E), threshold to increase forearm blood flow (37.09+ or -0.22 deg C in P vs 37.17+ or -0.26 deg C in E), slope of the sweating/esophogeal temperature relationship (0.42+ or -0.16 in P vs 0.41+ or -0.17 in E), or the slope of the forearm blood flow/esophogeal temperature relationship (10.04+ or -4.4 in P vs 9.61+ or -3.46 in E) were affected by 3 days of E2 supplementation. In the animal study, rats received daily subcutaneous injections of either a vehicle (sesame oil; n=18) or estradiol (10 ug/100ml g b.w.; n=18). Within each group, 3 subgroups were utilized: a) 4-day, b) 8-day, or (c) 12-day treatment. Four hours after the final daily injection, rats underwent a heat tolerance test (HTT) consisting of treadmill exercise at 21.5 m/min at 35 deg C until colonic temperature (Tc) reached 40.4 deg C. Vehicle treatment had no effect on initial Tc, time to reach 40.4 deg C, or heating rate between treatments. However, initial Tc values were reduced, heating rates were lower, and times to reach 40.4 deg C were increased in rats treated with E2 for 8 and 12 days compared with the 4-day treated group (P<0.05). Moreover, both initial Tc and heating rate were lower and time to 40.4 deg C was higher in E2- vs vehicle-treated rats for both 8- and 12-day protocols.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1996
- Accession Number
- ADB219046
Entities
People
- Carl V. Gisolfi
Organizations
- University of Iowa