2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
SEX DIFFERENCES IN THE EFFECTS OF PHYSICAL TRAINING ON
SWEAT GLAND FUNCTION
Yoshimitsu Inoue 1 , Tomoko Kuwahara-Ichinose 1 , Yukio Ogura 1 , Toyoshi Kubota 1 , Hiroyuki
Ueda 2 , Anna Ooue 3 , Narihiko Kondo 3
1 Laboratory for Human Performance Research, Osaka International University,
2 Osaka Shin-Ai College, 3 Lab. for Applied Human Physiology, Kobe University, Japan
Contact person: inoueyos@hus.oiu.ac.jp
INTRODUCTION
There are sex- and menstrual cycle-related differences in heat loss effector function (1-3).
During passive heating, we have found that heat loss in women, as compared with men,
depends more on cutaneous vasodilation than on sweating and that the lower rate of sweating
(SR) in women is attributable to lower sweat output per gland (SGO) and not to a lower
number of activated sweat glands (ASG) (1). The sex differences in sweating probably result
from differences in reproductive hormones, because testosterone promotes sweating and
estrogen inhibits it (4). Sweating is enhanced by physical training in both genders (2, 3), and
the increase in testosterone with physical training is considerably greater in men than in
women (5). Based on these results (2-5), the effects of physical training on sweating should
be more marked in men than in women. However, it is not yet clear whether sex differences
exist in the effects of physical training on sweat gland function, especially on SR, ASG, and
SGO. In this study, we compared the exercise- and acetylcholine-induced sweating in
physically trained (TF) and untrained (UF) females and males (TM, UM), to test the
hypothesis that enhanced sweat gland function with training is inferior in women compared
with men.
METHODS
This study consisted of two tests: exercise test and acetylcholine (Ach) iontophoresis test.
Thirty-seven volunteers (10 TF, 10 UF, 8 TM, and 9 UM) participated in the exercise, and 69
volunteers (17 TF, 25 UF, 14 TM, and 13 UM) participated in the iontophoresis test. Except
for gymnastics lessons, the UF and UM had not performed regular physical activity in the
previous 3 years. The TF and TM had participated in endurance sports for more than 6 years.
All of the female subjects had self-reported regular menstrual cycles of about 28 days and
were tested during the mid-follicular phase. Maximal oxygen uptake (VO2max) was estimated
using submaximal cycling. Experiments were conducted between Sept-Oct (2005-06).
Exercise test. Subject cycled in a semi-reclining position in a climatic chamber (28°C and
45% RH) for 60 min, then performed a continuous graded cycling at intensities of 35, 50 and
65% of VO2max for 20 min, without rest between intensities, in room air at 30°C and 45% RH.
During the test, SR was measured on the forehead, chest, back, forearm and thigh using
ventilated capsules (capacitance hygrometry). The number of ASG was determined at a site
adjacent to the sweat capsule using the starch-iodide technique during three exercise periods,
15-20, 35-40, and 55-60 min. The SGO at each site was calculated by dividing the respective
SR by the respective number of ASG. The rectal (Tre) and skin temperatures at five sites were
measured continuously, and the mean skin temperature (Tsk) and mean body temperature (Tb)
were calculated. The heart rate (HR) was measured continuously with an electrocardiogram.
The mean SR, number of ASG, and SGO for five body sites were calculated during the last 5
min (15-20, 35-40, and 55-60 min) at each exercise intensity.
Acetylcholine iontophoresis test. The tests were conducted in the sitting position, on a chair in
the testing chamber (25°C and 50% RH). Subjects were administered 10% Ach solution on
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