Body Regional Heat Pain Thresholds in Korean Young Males

Abstract

Sense of pain and temperature are extremely important for our survival. Cutaneous thermal thresholds have been measured by the method of either level or limit. The purpose of this study was to examine body regional heat pain thresholds using the method of both limit and level. A total of 16 young males (23.2 ± 3.2 yr, 174.9 ± 4.9 cm, 70.1 ± 8.6 kg, and 1.85 ± 0.12 m2) participated in this study. Subjects were laid in a supine position at an air temperature of 28oC and 35%RH. A thermal stimulator was used and the temperature increase of the probe was set at 0.1oC·s-1 for the method of limit and 0.5oC·step-1. All measurements were repeated three times on the following 14 body regions: the forehead, neck (back), chest, abdomen, upper back, upper arm, forearm, waist, hand, palm, thigh, calf, foot, and sole. For the method of limit, we measured warmth and heat thresholds along with heat pain thresholds on the 14 regions. The results showed that 1) pain thresholds were 3.2±2.1oC greater for the method of level than for the method of limit and this result corresponded to all 14 body regions (all P<0.05)

2) the correlation coefficient (r) between values by the two methods was 0.819 (N=14, P<0.01)

3) lower body regions (the thigh, calf and sole) had higher heat pain thresholds than upper body regions (the neck, chest, forearm and waist) by both methods

and 4) body regional subcutaneous fat thickness showed no relationships with heat pain thresholds except the upper arm. These results confirmed that the heat pain thresholds of the human body vary based on body sites, type of heat stimuli and the size of the area heated. This study also that the role of subcutaneous fat thickness on heat pain sensitivity could be a site specific phenomenon. Therefore, it could be inferred that the method of limit would be a better choice when dealing with thermal pain related to therapeutic or thermal use of heat such as hot packs whereas the method of level should be used in cases such as testing protective garments for firefighters.