2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
REGIONAL CHARACTERISTICS OF TEMPERATURE SENSATION
AND THERMAL COMFORT/DISCOMFORT IN HUMANS
Mayumi Nakamura 1 , Tamae Yoda 4 , Saki Yasuhara 2 , Yasuyo Saito 2 , Momoko Kasuga 1 , Kei
Nagashima 2, 3 , Larry I. Crawshaw 5, 6 1, 2, 3
, Kazuyuki Kanosue
1 2 3
Faculty of Sport Sciences, Faculty of Human Sciences, Consolidated Research Institute for
Advanced Science and Medical Care, Waseda University, Tokorozawa, Saitama, Japan
4
Faculty of International Liberal Arts, Dokkyo University, Saitama, Japan
5
Department of Biology, Portland State University, Portland, USA
6
Deptt of Behavioral Neuroscience, Oregon Health and Science University, Portland, USA
Contact person: m.nakamura@suou.waseda.jp
INTRODUCTION
Sensations evoked by thermal stimulation (temperature-related sensations) can be divided into
two categories, “temperature sensation” and “thermal comfort/discomfort” (Hensel, 1981).
Temperature sensations are utilized to obtain information concerning the thermal condition of
external objects or the environment, and are evoked by signals from warm and cold receptors
in the skin. Thermal comfort/discomfort is important for body temperature regulation in that it
drives an individual to search for the appropriate thermal environment to maintain normal
body temperature. Thermal comfort/discomfort is affected by the thermal state of not only the
skin but also the body core (Mower, 1976). We can discern local as well as whole body
responses for both temperature sensation and thermal comfort/discomfort (Hensel, 1981).
Understanding differences in the regional sensitivity of temperature related sensations is
valuable not only from a physiological point of view but also for the design of a comfortable
environment and efficient clothes. It is also useful for providing optimal medical and nursing
care. Several studies have investigated regional sensitivity, but only for temperature sensation
(Nadel et al. 1973; Stevens et al. 1974; Crawshaw et al. 1975). Little is known about regional
differences in thermal comfort/discomfort (Cotter and Taylor, 2005). Recently we reported
several aspects of sensitivity in temperature sensation and thermal comfort/discomfort
(Nakamura et al. 2006). Interestingly, the face tended to be more sensitive to heat than other
parts of the body in the production of discomfort, while the abdomen tended to be more
sensitive to cold. These tendencies were not conclusive, since the experiment was done only
with whole body heat or cold exposure. In the present study, we examined regional
differences in temperature sensation and thermal comfort/discomfort by applying local
temperature stimulation. We paid special attention to the face and abdomen, and utilized the
chest and thigh as comparison regions.
METHODS
Experiment 1 (mild heat exposure): This series of experiment was done in the period from
November to December, 2006. Ten healthy male subjects participated in this study. Each
subject gave informed consent for the experimental protocol, which was approved by the
Human Research Ethics Committee in the Faculty of Sport Sciences, Waseda University.
Subjects sitting in a room at 32-33 were locally cooled and warmed with water perfused
stimulators (270 cm 2 ) made with vinyl tubes (7 mm in diameter). The water temperature for
basal, cooling, and warming conditions were 35 , 25 , and 42 respectively. The areas
stimulated were the face, chest, abdomen and thigh. Each stimulus lasted 90 sec. The interval
between each stimulus was 4.5 min. The order of the four areas stimulated and the order of
cooling and warming were randomly chosen. Temperature sensation and thermal
comfort/discomfort of the stimulated area and those of the whole body were reported by the
subject whenever he felt any change in the sensations. This was made by using dials
numbered from -10 (“very cold” or “very uncomfortable”) to 10 (“very hot” or “very
368