| Summary: | Previous research have showed that cold injuries of feet occur more often than cold injuries of hands. Recently, an unexpectedly large number of cold injuries were observed during military training in Norway and a relationship between cold injuries and the use of the Alico ski boot was suspected. The Marine Corps and the Defence Clothing agency asked TNO to investigate whether the Alico ski boot, in combination with the Berghaus gaiter, and the arctic sock would lead to an increased risk for cold injuries. Tests with several ski boot combinations were performed to measure the water vapour transport and the water tightness. Both worn and unworn ski boots were tested with and without a gaiter. The results were compared with the results of the Meindl climbing boot. The water vapour transport was measured using a thermal sweating foot model which was placed in a boot combination during three days for a couple of hours (indicate a more precise duration) a day. The water tightness was measured using a walking simulator where boots walked in a water tank. Both worn ski and climbing boots were tested by 8 marines in a climatic chamber of -18¦C. The subjects rested on a chair in the climatic chamber for the first half hour, walked on a treadmill for the second half hour and stood still for the last half hour. Several skin temperatures (indicate the number of sites) of the feet were measured. The subjects also provided regular information about their thermal sensations and comfort. A worn ski boot has higher water vapour absorption and lower water vapour transmission than an unworn ski boot. During water evaporation periods about half of the water absorption evaporated from both worn and unworn boots. Wearing a gaiter with the ski boot gives a lower water vapour transmission and a higher resistance to heat. The ski boots have higher water vapour absorption, a slightly lower water vapour desorption and a slightly lower water vapour transmission than the climbing boot. None of the tested boots are waterproof. More water leaks in a worn ski boot than in an unworn ski boot. The climbing boot gives the best results on water tightness. No significant differences were found between the different kind of boot combinations concerning temperature and comfort and thermal sensations. Worn ski boots absorb more sweat and evaporate less sweat than unworn ski boots. By wearing a gaiter even less sweat can evaporate. The ski boots are not waterproof and water leaks in faster when shoes are worn. The climbing boots are not waterproof either, but water leaks in slower and the feet stay dry for longer periods. The boot combinations give equal temperatures and temperature decreases or increases. Also the comfort and thermal sensations are equal. The greatest problem is the ski boot not being waterproof which gives more leaking in of water and a faster cooling down of the feet. This could lead to earlier development of cold injuries.
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