2007, Piran, Slovenia

Occupational Thermal Problems
PERIPHERAL SKIN TEMPERATURES DURING 12 DAYS MILITARY
MANOEUVRE IN WINTER CONDITIONS
Sirkka Rissanen 1 , Hannu Rintamäki 1,2 , Juha Oksa 1 , Tero Mäkinen 1 , Ari Peitso 3
1
Finnish Institute of Occupational Health, Oulu, Finland
2
Department of Physiology, University of Oulu, Oulu, Finland
3
Finnish Defence Forces, Centre for Military Medicine, Lahti, Finland
Contact person: sirkka.rissanen@ttl.fi
INTRODUCTION
In sustained military operations, soldiers are often exposed to various stresses such as
prolonged and strenuous physical exercise combined with sleep, energy and fluid deficiency,
extreme ambient temperature and time pressure. Thermal responses of soldiers are rarely
monitored with continuous daily measurements and therefore it would be important to know
if there exists tissue temperatures low enough to cause risk for performance loss or tissue
damages in winter. Castellani et al. (2003) studied the effects of a 3.5 day military operation
on thermoregulatory responses to cold stress but made the measurements after the operation.
Rintamäki et al. (1993) showed that a long-term exposure to cold during field training may
develop local cold acclimatization of the periphery. The purpose of this study was to examine
peripheral skin temperatures, persistence of possible individual differences in peripheral skin
temperatures throughout the manoeuvre and any signs of local acclimatization to cold during
the manoeuvre in winter conditions.
METHODS
The subjects were 8 male joggers. Their physical characteristics were (mean ± SE): age 19.8
±0.2 y, height 175.8 ±2.7 cm, body mass 72.4 ±3.0 kg and body fat 14.8 ±1.0 %. The study
was approved by the Ethic Committee of the Hospital District of Helsinki and Uusimaa,
Finland. All subjects were informed of all details of the experimental procedures. Each
subject gave his written informed consent prior the experiment.
During the manoeuvre mean ambient temperature was -5°C with a range of -20-2°C and mean
velocity of the wind was 0.7 m/s (range 0 - 3.1 m/s). Mean relative humidity was 92% and
total amount of snow fall was 17 mm/12 days. The soldiers were wearing military combat
clothing which thermal insulation varied 0.112-0.438 m 2 K/W depending on the amount of
layers worn in different weather or activity conditions. They slept in heated tents.
The 12-day military manoeuvre was carried out in December and it consisted of a combat
training (C) followed by a combat shooting training (CS). Skin temperature was measured at
seven sites using thermistors (NTC DC95, Digi-key, USA). Temperatures were saved at 1
min intervals into a data logger (SmartReaderPlus8, ACRSystems, Canada). Mean skin
temperature (Tsk) was calculated as an area weighted average. Heart rate was recorded by a
heart rate monitor (Polar S610i, Polar Electro Oy, Finland) and saved at 1-min intervals.
For 1.5 days between the training periods the monitoring equipments were taken off the
subjects and no measurements were performed. In addition, on day 1 and day 12 only a part
of the days were active military training and therefore the measured data are excluded from
the analysis. Only data from active time, between 0530 and 1800 were selected for the
analysis.
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