Physiological responses of the human extremities to cold water immersion.

Five subjects immersed their hands and feet twice during 1 hour sessions in a calorimeter bath, filled with water at 25 degrees C. Before immersion the hand (33.0 +/- 2.2 degrees C) was warmer than the foot (30.6 +/- 2.1 degrees C) and so was the blood flow: respectively 5.8 +/- 5.2 versus 0.7 +/- 0.3 ml.min-1.100 mo tissue-1 as determined by strain gauge plethysmography and 10.8 +/- 5.1 versus 6.7 +/- 5.3 by the doppler method. At the end of the immersion period the blood flow had decreased a factor of 2.9 (doppler) and 4.3 (plethysmography). The local heat transfer, determined by heat flux transducers, was highest immediately after immersion. The maximum was higher at the ventral sides than at the dorsal sides of the hand (225 +/- 93 versus 186 +/- 61 W.m-2 and the foot (178 +/- 53 versus 160 +/- 57 W.m-2). The total heat transferred to the water by hand or foot during the 60 minutes of immersion, determined by calorimetry, was 47 +/- 21 and 36 +/- 36 kJ respectively and was not statistically different due to considerable interindividual differences. Interindividual differences were also found for heat flux, rectal and local skin temperature and blood flow. These differences will have to be taken into account if a comparison is made with data from subjects with local cold injuries.