Previous recreational cold exposure does not alter endothelial function or sensory thermal thresholds in the hands or feet

Abstract

New findings: What is the central question of this study? Does recreational cold exposure result in cold sensitivity and is this associated with endothelial dysfunction and impaired sensory thermal thresholds? What is the main finding and its importance? Previous cold exposure was correlated with cold sensitivity of the foot, which might indicate the development of a subclinical non-freezing cold injury. Endothelial function and thermal detection were not impaired in cold-sensitive individuals; therefore, further research is required to understand the pathophysiology of subclinical and clinical forms of non-freezing cold injury.

Abstract: In this study, we investigated whether cold-sensitive (CS) individuals, who rewarm more slowly after a mild cold challenge, have impaired endothelial function and sensory thermal thresholds (STTs) and whether this is related to reported cold exposure. Twenty-seven participants with varying previous cold exposure undertook three tests: an STT test, i.e. determination of warm and cold STTs of the fingers and dorsal foot; an endothelial function test, i.e. measurement of cutaneous vascular conductance (CVC) during iontophoresis of ACh on the forearm, finger and foot; and a CS test, involving immersion of a foot for 2 min in water at 15°C followed by 10 min of rewarming in air at 30°C. Toe skin temperature (T_sk ) measured during the CS test was used to form a CS group (<32°C before and 5 min after immersion) and an otherwise closely matched control group [T_sk >32°C; n = 9 (four women) for both groups]. A moderate relationship was found between cold exposure ranking and T_sk rewarming (r = 0.408, P = 0.035, n = 27) but not STT or endothelial function. The T_sk and blood flow were lower in CS compared with control subjects before and after foot immersion [T_sk , mean (SD): 30.3 (0.9) versus 34.8 (0.8) and 27.9 (0.8) versus 34.3 (0.8)°C, P < 0.001; and CVC: 1.08 (0.79) versus 3.82 (1.21) and 0.79 (0.52) versus 3.45 (1.07) flux mmHg^-1 , n = 9, P < 0.001, respectively]. However, no physiologically significant differences were observed between groups for endothelial function or STT. A moderate correlation between previous cold exposure and toe T_sk rewarming after foot immersion was observed; however, CS was not associated with impaired endothelial function or reduced thermal detection.

Keywords: cold sensitivity; extreme environments; non-freezing cold injury; vascular function.