2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
during each rest period. For both the control trial and the hot-dry trial with active cooling,
subjects completed 120 min of cycling. However, for the hot-dry trial with no cooling, only
one subject could exercise for 120 min. Trials were terminated with core temperature >39.5°C
(N=2) or at volitional fatigue (N=5), with an average trial duration of 98.3 (SD 13.3) min.
The following physiological measurements were recorded at 0.2Hz, using a portable data
logger (Grant instruments Ltd., 1206 Series Squirrel, U.K.): core temperature (mean of
insulated auditory canal temperature and rectal temperature (Edale Instruments Ltd,
Cambridge, U.K.)), skin temperature from eight sites (Type EU, Yellow Springs Instruments
Co. Ltd., Yellow Springs, OH, U.S.A.), and heart rate (Polar Electro Sports Tester, Finland).
Body mass changes were also measured, and were corrected for drinking, urine production
and sweat retained within the clothing. At 15-min intervals, data were collected for perceived
work effort (15-point Borg scale), thermal sensation and thermal discomfort.
Cognitive function was evaluated using the Mini-Cog rapid assessment battery (Shephard and
Kosslyn, 2005) administered via a personal digital assistant (PDA, PalmOne, Tungsten C,
U.S.A.), after first completing 8-10 h of preliminary training (Figure 1). The test battery was
administered every 15 min, and included: vigilance; three-term reasoning; filtering; verbal
working memory, divided attention and perceptual reaction time. The test battery took
approximately 10-13 min to complete, with testing performed whilst subjects exercised. Thus,
subjects were exposed to an almost continuous mental challenge.
Figure 1: Verbal working memory test performed on a PDA.
RESULTS
Physiological and cognitive function data for the last 5 min of each trial are summarised in
Table 1. Each of the physiological and psychophysical variables were significantly different
for both the control trial and the hot-dry trial completed with active liquid cooling (P0.05).
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