Cold-induced vasodilatation response in the fingers at 4 different water temperatures.

We evaluated the cold-induced vasodilatation (CIVD) response at 4 different water temperatures. Nine healthy young male subjects immersed their right hands in 35 °C water for 5 min, and immediately thereafter for 30 min in a bath maintained at either 5, 8, 10, or 15 °C. The responses of finger skin temperatures, subjective ratings of thermal comfort and temperature sensation scores were compared between the 4 immersion trials. The number of subjects who exhibited a CIVD response was higher during immersion of the hand in 5 and 8 °C (100%) compared with 10 and 15 °C water (87.5% and 37.5%, respectively). The CIVD temperature amplitude was 4.2 ± 2.6, 3.4 ± 2.0, 2.1 ± 1.6, and 2.8 ± 2.0 °C at 5, 8, 10, and 15 °C trials, respectively; higher in 5 and 8 °C compared with 10 and 15 °C water (p = 0.003). No differences in CIVD were found between the 5 and 8 °C immersions. However, during immersion in 5 °C, subjects felt "uncomfortable" while in the other trials felt "slightly uncomfortable" (p = 0.005). The temperature sensation score was "cold" for 5 °C and "cool" for the other trials, but no statistical differences were observed. Immersion of the hand in 8 °C elicits a CIVD response of similar magnitude as immersion in 5 °C, but with less thermal discomfort.