2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
280
EXPERIMENTS AND ANALYSIS OF SWEATING CONTROL IN
HUMAN THERMOREGULATION SYSTEM
Shintaro Yokoyama, Takafumi Maeda and Masashi Kuramae,
Hokkaido University, Sapporo, Japan
Contact person: yokoyama@eng.hokudai.ac.jp
INTRODUCTION
We examined our mathematical model of human sweating, which is an important
thermoregulatory mechanism. We performed physiological experiments to quantify the
characteristic differences among younger males, younger females and elderly persons. By
using measured results of sweating rate, we evaluated the validity the present mathematical
model for the control of sweating. The results showed there were no great sweating
differences among the three groups. Secondly, it was observed there were not wide seasonal
differences in sweating between the summer and winter for each of three groups. Therefore, it
was concluded that the present mathematical model of sweating rate was suitable for use not
only with younger males, but also with younger females and the elderly.
METHODS
Mathematical Model of Sweating: The present mathematical models of sweating control
expressing local characteristic of each segment are as follows. Local perspiration rate (Ei;
W/m 2 ) could be predicted using Equations 1 and 2.
Ei = i
(Thy Thy0)+ (Tsm Tsm0) exp{(Tsi Tsm0)/ } dTsm/dt - 0 0 Eqn. 1
Ei = i (Thy Thy0)+ (Tsm Tsm0) dTsm/dt 0 exp{(Tsi Tsm0) / }
dTsm/dt - 0 0 Eqn. 2
where: t: time [min], Thy : hypothalamic temperature [ ], Tsm: mean skin temperature [ ], Tsi :
local skin temperature in i-th compartment [ ], Thy0 : set point of hypothalamic temperature [ ],
Tsm0 : set point of mean skin temperature [ ], εi : coefficient of local perspiration rate at i-th
compartment [-], γ: numerical value with perspiration control effect (W/m 2 )/( /min) , r0 :
numerical value with perspiration control effect [ /min .
The present mathematical models were based on the experimental results of male subjects.
Experimental Procedures: We performed subjective experiments to quantify the characteristic
differences of sweating control among younger males, younger females and elderly persons.
By using measured results of sweat rate, we also evaluated the validity the present
mathematical model for the control of sweating to all three groups. The number of younger
male, female and elderly subjects were nine, six and eleven, respectively, and their physical
characteristics are shown in Table 1.
Table 1. Physical characteristics of the three groups.
Height Weight
Age [age] [cm] [kg]
Male 24.1±2.73 174.4±3.65 63.4±4.72
Female 21.5±1.38 161.8±6.59 52.7±3.93
Elderly 72.3±2.73 149.3±3.77 51.6±7.77
The experiments were performed at a climatic chamber of the Laboratory of Environmental
Ergonomics, Hokkaido University in the summer of 2006. All subjects wore the same type of
T-shirt and short pants. The feet and the crura were immersed in hot water of 42 . The
sublingual temperature and skin temperatures of seven points were measured with thermistor.