Kakitsuba Naoshi, Mekjavic Igor B
Department of Environment and Technology, School of Science and Technology, Meijo University, 468-8502 Shiogamaguchi 1-501, Tenpaku-ku, Nagoya, Aichi Prefecture, Japan.
Jozef Stefan Institute, Ljubljana, Slovenia.
J Physiol Anthropol. 2017 Jun 21;36(1):27. doi: 10.1186/s40101-017-0141-y.
The core interthreshold zone (CIZ) is defined as the range between temperatures at the onset of shivering and sweating. Its circadian or diurnal variation has not been extensively studied. The present study examined whether the CIZ is subject to a diurnal rhythm. In addition, according to the previous finding that the CIZ was proportionally correlated with peripheral interthreshold zone (PIZ), it was also examined whether cutaneous sensation threshold zone (CSZ), a determinant of the PIZ, is correlated with the CIZ.
The CIZ and the CSZ were measured in ten Japanese men who underwent three experiments in a single day on the morning, afternoon, and evening in the 2014 experiment (so-called single-day experiment) and six Japanese men underwent the same experiments on the morning of day 1, the afternoon of day 2, and the evening of day 3 in the 2015 experiment (so-called multiple-day experiment). Air temperature was controlled at 20-24 °C. Each subject wore a suit perfused with 25 °C water at a rate of 600 cm/min and exercised on an ergometer at 50% of their maximum work rate for 10-15 min until their rate of sweating increased. They then remained seated without exercising until their oxygen uptake increased. Rectal temperature, skin temperatures at seven sites, the sweating rate at the forehead, and oxygen uptake were continuously monitored throughout experiment. Cutaneous warm and cold sensation thresholds at three sites were measured using 1- and 2-cm probes.
The results from the single-day experiment demonstrated a small change in the CIZ and core temperature prior to exercise (T ) whereas those from the multiple-day experiment demonstrated continuous increase in the CIZ and T . The CSZ measured with a 1-cm probe was inversely proportional to the average skin temperature at three sites prior to measurement (T ).
The results suggested that the CIZ may be not dependent on time of a day but T per se and may not be associated with the CSZ.
核心阈间区（CIZ）被定义为寒战起始温度与出汗起始温度之间的范围。其昼夜节律变化尚未得到广泛研究。本研究探讨了CIZ是否存在昼夜节律。此外，根据之前发现CIZ与外周阈间区（PIZ）呈比例相关，还研究了作为PIZ决定因素的皮肤感觉阈值区（CSZ）是否与CIZ相关。
在2014年的实验中（所谓的单日实验），对10名日本男性进行了三项实验，分别在上午、下午和晚上进行，测量了他们的CIZ和CSZ；在2015年的实验中（所谓的多日实验），对6名日本男性进行了同样的实验，分别在第1天上午、第2天下午和第3天晚上进行。空气温度控制在20 - 24°C。每个受试者穿着一套以600 cm/min的速率灌注25°C水的套装，并在测力计上以其最大工作速率的50%锻炼10 - 15分钟，直到出汗率增加。然后他们保持坐姿不运动，直到摄氧量增加。在整个实验过程中持续监测直肠温度、七个部位的皮肤温度、前额的出汗率和摄氧量。使用1厘米和2厘米的探头测量三个部位的皮肤冷热感觉阈值。
单日实验结果显示运动前CIZ和核心温度（T）变化较小，而多日实验结果显示CIZ和T持续升高。用1厘米探头测量的CSZ与测量前三个部位的平均皮肤温度（T）成反比。
结果表明，CIZ可能不依赖于一天中的时间，而是依赖于T本身，并且可能与CSZ无关。
