2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
of skin temperature at the hand, bicep, chest, thigh and calf. Rectal temperature (Trec) was
measured by a rectal thermometer inserted 10cm past the anal sphincter. Aural temperature
(Taur) was measured by an aural thermistor inserted into the external auditory meatus and
insulated with cotton wool. Mean skin temperature (Tms) was calculated using the equation of
Ramanathan (1964). All temperatures were recorded via a Squirrel data logger (1000 Series,
Cambridge, UK). Fingertip arterialised capillary blood samples were taken for the analysis of
Haematocrit (Hct), haemoglobin (Hb) and blood lactate (BLa). Participants then entered the
heat controlled laboratory (34.6 ±0.3°C) and resting expired gas was collected for 5 minutes
prior to undertaking the intermittent exercise protocol. Core and skin temperature
measurements, heart rate and BLa were recorded at rest in the cool, at rest in the heat, 5, 10,
15 and 20 minutes of intermittent exercise, at the end of the cooling/ non cooling period and
at volitional exhaustion. Ratings of perceived exertion (RPE; Borg Scale) and the thermal
strain (TS) of the subject were also recorded at exercise time points. Further Hct and Hb
samples were taken post exercise for calculation of plasma volume and nude body mass
recorded to estimate fluid loss.
Differences in variables between trials were analysed by two-way ANOVA with repeated
measures on both factors (trial x time). A one-way ANOVA was used to determine the
differences between the performance trials and weight loss. A paired T-test was used to
compare the difference between the heat lost through the hands in the two cooling trials.
RESULTS
No significant interaction was observed for Trec at rest, throughout the intermittent exercise or
at volitional exhaustion (P>0.05). Trec increased from rest (37.2 ±0.2, 37.1 ±0.3, 37.2 ±0.3°C
for CON, 1-HC and 2-HC, respectively; P>0.05) to 38.3 ±0.3°C after 20 min in all trials
(P0.05). No significant
interaction was observed for Taur at rest or throughout the intermittent exercise (P>0.05) with
values peaking at 37.7 ±0.4, 37.6 ±0.4 and 37.4 ±0.4 for CON, 1-HC and 2-HC, respectively
at 20 minutes. A main effect between trials for Taur, however, was observed after cooling
between CON and 2-HC (P0.05). At volitional exhaustion both Trec (38.6 ±0.8, 38.4 ±0.7, 38.7 ±0.5°C) and Taur (37.9
±0.4, 38.0 ±0.7, 37.7 ±0.7°C) measures were similar between trials for CON, 1-HC and 2-HC,
respectively (P>0.05).
There were no significant differences between Tms values at the end of 20 minutes intermittent
exercise with values reaching 36.3 ±0.5°C, 35.9 ±0.6°C and 35.9 ±0.7°C for CON, 1-HC and
2-HC, respectively (P>0.05). Thand was cooler at the end of the cooling procedure for 1-HC
(23.2 ±1.7°C) and 2-HC (23.7 ±1.4°) when compared to CON (35.9 ±0.6°; P0.05). The heat lost from the hands
during 2-HC (41.7 ±6.9 cal.s -1 ) was greater than when compared to 1-HC (35.1 ±5.9 cal.s -1 ;
P