Relationship between Peripheral Cold Tolerance and Morphological Characteristics Based on Cold-Induced Vasodilation in the Fingers: to Protect Workers in Cold Environments

The present study aimed to investigate the relationship between morphological parameters and local cold tolerance in the fingers to improve cold-protective interventions for workers under cold stress. Nine males (24.3 ± 3.5 y in age, 177.3 ± 4.1 cm in height, 73.1 ± 10.4 kg in body weight, 14.0 ± 3.4% in total body fat, and body mass index [BMI] of 23.2 ± 2.9 kg/㎡) participated in a cold-induced vasodilation test (CIVD), for evaluating local cold-tolerance. Subjects immersed the 3rd finger of one hand in water at a temperature of 4.5℃ The trial consisted of a 10-min rest, 30-min finger immersion into cold water, and a 10-min recovery at an air temperature of 25℃. The results showed that the minimum and maximum temperatures on the third finger (TSUBmin/SUB and TSUBmax/SUB), the onset time of CIVD, and the frequency of the CIVD waves were 5.7 ± 1.7℃, 12.3 ± 2.3oC, 3.8 ± 1.1 min, and 6.6 ± 1.1 times, respectively. There were significant relationships between the CIVD parameters and total body fat (%BF), BMI, or body weight. Specifically, subjects with a greater %BF or BMI had higher TSUBmin/SUB (r=0.624 for %BF, r=0.595 for BMI) and TSUBmax/SUB (r=0.700 for %BF, r=0.645 for BMI). In addition, a higher CIVD frequency resulted in a higher finger temperature during recovery after the cold immersion (r=0.698, p=0.037). These results indicate that morphological parameters, such as total body fat and BMI, can reflect the local cold tolerance of the hands. Individuals who have bulkier body physiques can better tolerate cold in their hands.