Influence of gender and menstrual cycle on a cold air tolerance test and its relationship to thermosensitivity

This investigation evaluated the influence of gender and phase of menstrual cycle [follicular (FOL): Days 2-6) and luteal (LUT: Days 19-24)] on a cold air tolerance test (CATT: 90-min of exposure to 5 degreesC air) in 8 femal es (22.7 +/-3.0 yr) and 15 males (22.3 +/-2.9 yr). In addition, central the rmosensitivity (beta; W (.) kg(-1) (.) degreesC(-1)) [i.e., the slope of th e relationship between the decrease in esophageal temperature (T.) and the increase in heat production (HP)], gathered during a separate water trial i n 20 degreesC water, was correlated to the change (Delta) in T-es and HP ac ross the 90 min of resting exposure during the CATT. Analysis of variance r evealed no significant differences between phase of menstrual cycle or gend er for HP, mean skin temperature (T-sk), and insulation; however, a main ef fect for time for these parameters was demonstrated. Despite these similari ties, T-es differed (P < 0.05) between males and females. Additionally, no relationship was found between beta and Delta HP and DeltaT(es). in the mal es and females. Also, there was no relationship between beta and thermoregu lation during the CATT in these subjects. These data suggest that menstrual cycle phase did not cause a differential response in T-es, (T) over bar (s k) and HP during a CATT Furthermore, women maintained a higher T-es than me n during the CATT despite similarities in HP and (T) over bar (sk).