Palm cooling does not reduce heat strain during exercise in a hot, dry environment.

To compare the effectiveness of the rapid thermal exchange device (RTX) in slowing the development of hyperthermia and associated symptoms among hand immersed in water bath (WB), water-perfused vest (WPV), and no cooling condition (NC). Ten subjects performed 4 heat stress trials. The protocol consisted of 2 bouts of treadmill walking, separated by a cooling-rehydration period. The times to reach the predetermined rectal temperature in the first (38.5 degrees C) and second bouts (39 degrees C) were not different among RTX, NC, and WB, but was longer for the WPV in both bouts (p<0.05). Heat storage was significantly lower for WPV only in the first bout vs. the other conditions (p<0.05). Heart rate (HR) was not different at 10, 20, and 30 min during the first bout among RTX, NC, and WB, but was lower for WPV (p<0.05). HR was not different among conditions during the second bout. The RTX was not effective in slowing the development of hyperthermia.