2007, Piran, Slovenia

Sweating
MENSTRUAL CYCLE DOES NOT AFFECT POSTEXERCISE
SWEATING AND SKIN BLOOD FLOW RESPONSE
Emily Leclair 1 , Lindsay Nettlefold 1 , Ronald J. Sigal 2 , Ollie Jay 1 Glen P. Kenny 1
1 University of Ottawa, School of Human Kinetics, Laboratory of Human Bioenergetics and
Environmental Physiology, Ottawa, Ontario, Canada and 2 University of Calgary, Department
of Medicine, Calgary, Alberta, Canada.
Contact Person: gkenny@uottawa.ca
A number of studies demonstrate that exercise induces a residual effect on thermal control,
resulting in an increase in the postexercise threshold for sweating and skin vasodilation. The
magnitude of these increases is greater in females in comparison to males. However, within
females little is known about the effect of the menstrual cycle on postexercise heat loss
responses. The purpose of the following study was to examine the menstrual cycle-related
changes in postexercise sweating and skin blood flow responses. Five female participants
underwent a postexercise passive heat exposure during the early follicular phase (FP) and
mid-luteal phase (LP), which were confirmed by assaying plasma female reproductive
hormones. Subjects were initially habituated at an ambient air temperature of 24ºC for a
minimum of 30-min, then performed 30-min of moderate-intensity cycle ergometry (75%
•
VO2peak). Immediately following exercise, subjects remained upright seated for 15-min
resting recovery, and then donned a liquid conditioned suit. Mean skin temperature was
clamped at ~34 o C for ~15 min after which mean skin temperature was increased at a rate of
~4.5ºC•h -1 until thresholds for forearm vasodilation and upper back sweating were clearly
established. Local forearm skin temperature was clamped at 34ºC throughout the warming
period. It was found that the magnitude of increase in the esophageal temperature at which
onset of skin vasodilation and sweating occurred was similar for FP and LP (p>0.05). The
onset threshold for sweating was 0.39ºC and 0.38ºC above baseline resting Tes for FP and LP
respectively. The increase in Tes above baseline at which skin vasodilation occurred was
0.33ºC and 0.43ºC for FP and LP respectively. The slope of the linear relationship between
local upper back sweat rate and Tes were not different between both phases (p>0.05).
Similarly, the rate of rise of cutaneous vascular conductance per unit change in Tes was not
significantly different between FP and LP (p>0.05). These results demonstrate that the
menstrual cycle does not modify the postexercise heat loss responses.
This research was supported by a Discovery Grant from the Natural Sciences and Engineering
Research Council of Canada.
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