2007, Piran, Slovenia

Acute and chronic heat exposure
Table 1: Averaged data for the last 5 min of each trial, or the last data collection period. Data
are means with standard errors of the means. * = significantly different from the “hot: no
cooling” trial (P0.05). It was evident, however,
that patterns of cognitive performance decrement appeared towards the end of the “no
cooling” trial. This appeared in the form of a dramatic elevation in the error rate for reasoning
and divided attention.
DISCUSSION
The current study has provided an evaluation of the thermal impact on physiological and
cognitive functions whilst wearing biological and chemical protective clothing in hot-dry
conditions. In addition, the ability of a liquid-cooling garment to ameliorate adverse changes
was evaluated. It the latter instance, the liquid-cooling garment (water temperature 15°C),
successfully prevented all decrements in physiological function observed during the hot-dry
trial without cooling.
Although thermal strain clearly impacted upon physiological performance, undesirable effects
were not observed for the cognitive function indices. Whilst it is quite probable that some
degree of hyperthermia heightens cognitive function, it is also probable that subjects were not
sufficiently dehydrated to experience the full effects of exposure. For instance, Gopinthan et
al. (1988) have demonstrated that a positive correlation exists between the severity of
dehydration and detriments in cognitive function, and Szinnai et al. (2005) found that no
changes were evident unless individuals experienced moderate dehydration (2-5% body mass
loss). In the current study, subjects only experienced mild dehydration, with an average body
mass change of 2.1% at completion of the most stressful condition.
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