The trainability and contralateral response of cold-induced vasodilatation in the fingers following repeated cold exposure

Cold-induced vasodilatation (CIVD) is proposed to be a protective response to prevent cold injuries in the extremities during cold exposure, but the laboratory-based trainability of CIVD responses in the hand remains equivocal. Therefore, we investigated the thermal response across the fingers with repeated local cold exposure of the whole hand, along with the transferability of acclimation to the fingers of the contralateral hand. Nine healthy subjects immersed their right hand up to the styloid process in 8°C water for 30 min daily for 13 days. The left hand was immersed on days 1 and 13. Skin temperature was recorded on the pads of the five fingertips and the dorsal surface of the hand. The presence of CIVD, defined as an increase in finger skin temperature of 0.5°C at any time during cooling, occurred in 98.5% of the 585 (9 subjects × 5 sites × 13 trials) measurements. Seven distinct patterns of thermal responses were evident, including plateaus in finger temperature and superimposed waves. The number (N) of CIVD waves decreased in all digits of the right hand over the acclimation period (P = 0.02), from average (SD) values ranging from 2.7 (1.7) to 3 (1.4) in different digits on day 1, to 1.9 (0.9) and 2.2 (0.7) on day 13. Average (SD) finger skin temperature (T _avg) ranged from 11.8 (1.4)°C in finger 5 to 12.7 (2.8)°C in finger 3 on day 1, and then decreased significantly (P < 0.001) over the course of the training immersions, attaining values ranging from 10.8 (0.9)°C in finger 4 to 10.9 (0.9)°C in finger 2 on day 13. In the contralateral hand, N was reduced from 2.5 to 1.5 (P < 0.01) and T _avg by ∼2°C (P < 0.01). No changes were observed in thermal sensation or comfort of the hand over the acclimation. We conclude that, under conditions of whole-hand immersion in cold water, CIVD is not trainable and may lead to systemic attenuation of thermal responses to local cooling.