Thermoregulatory responses to cold transients: effects of menstrual cycle in resting women

• Published in: Journal of applied physiology (1985) Vol. 85; no. 2; pp. 543 - 553
• Main Authors: Gonzalez, Richard R, Blanchard, Laurie A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01-08-1998; American Physiological Society
• Subjects: Adult; Anatomy & physiology; Biological and medical sciences; Body Temperature Regulation - physiology; Calorimetry; Cold Temperature - adverse effects; Estradiol - blood; Female; Fundamental and applied biological sciences. Psychology; Humans; Menstrual Cycle - physiology; Menstruation; Progesterone - blood; Rest - physiology; Shivering - physiology; Skin Temperature - physiology; Temperature; Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Human; Temperature; Menstrual cycle; Cold; Clothing; Thermoregulation; Environmental factor; Shivering; Estradiol; Thermogenesis; Hormonal regulation; Female; Progesterone
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1998.85.2.543

Biophysics and Biomedical Modeling Division, US Army
Research Institute of Environmental Medicine, Natick, Massachusetts
01760-5007
Effects of the
menstrual cycle on heat loss and heat production
( M ) and core and skin temperature
responses to cold were studied in six unacclimatized female nonsmokers
(18-29 yr of age). Each woman, resting supine, was exposed to a
cold transient (ambient temperature = mean radiant temperature = 20 to
5°C at 0.32°C/min, relative humidity = 50 ± 2%, wind speed = 1 m/s) in the follicular (F) phase
( days 2-6 ) and midluteal (L)
phase ( days 19-23 ) of her menstrual cycle. Clothed in each of two ensembles with different thermal resistances, women performed multiple experiments in the F and
L phases. Thermal resistance was 0.2 and 0.4 m 2  · K · W 1
for ensembles A and
B , respectively. Esophageal
temperature (T es ), mean weighted
skin temperature
( sk ),
finger temperature (T fing ), and
area-weighted heat flux were recorded continuously. Rate of heat debt
( S ) and integrated mean body
temperature
( b,i )
were calculated by partitional calorimetry throughout the cold ramp. Extensive peripheral vasoconstriction in the F phase during early periods of the ramp elevated T es
above thermoneutral levels. Shivering thermogenesis
( M  =  M     M basal ,
W /m 2 ) was highly correlated with
declines in
sk and
T fing
( P <0.0001). There was a reduced
slope in M as a function of
b,i in
the L phase with ensembles A
( P  < 0.02) and
B ( P  < 0.01). Heat flux was higher and
S was less in the L phases with
ensemble A
( P < 0.05). An analytic model
revealed that
sk and
T es contribute as additive inputs
and T fing has a multiplicative
effect on the total control of M
during cold transients
( R 2  = 0.9).
Endogenous hormonal levels at each menstrual cycle phase, core
temperature and
sk
inputs, vascular responses, and variations in body heat balance must be
considered in quantifying thermoregulatory responses in women during
cold stress.
clothing; regional heat flux; thermoregulatory model