Cognitive, psychomotor, and physical performance in cold air after cooling by exercise in cold water.Aviat Space Environ Med. 2007 Jun; 78(6):568-73.AS
This study evaluated performance after lowering core temperature at different rates while local tissues were either cooled (lower body) or not cooled (upper body).
There were 10 men who volunteered to perform up to 8 cold water immersions (CWI) at combinations of 2 water temperatures (10 degrees C and 15 degrees C), 2 depths [waist (W), chest (C)], and 2 walking speeds (0.44 or 0.88 m x s(-1)) until their core temperature fell to 35.5 degrees C, stabilized above that temperature, or they requested to stop. They also completed a control trial (120 min rest in 19 degrees C air). Immediately following each CWI and control, cognitive and physical performance tests were performed in cold air (10 degrees C; CAE).
Overall, the CWI protocol lowered rectal temperature by 0.3-1.0 degrees C. Mean skin temperature was approximately 26 degrees C and finger temperature was approximately 15 degrees C during CAE. No statistical differences were observed across trials for any cognitive test. On the physical performance tests, step test performance was degraded approximately 12% on CWI trials compared with control, but there were no differences in manual dexterity, hand grip strength, marksmanship, or pull-ups.
These results indicate that cognitive performance can be maintained despite mild hypothermia, and that physical performance is related to local tissue temperature, not a moderately reduced core temperature.