Actually it is dangerous - Cold intolerance (2/4)

Q6. If you have cold intolerance, you feel cold in your hands and feet, but there is cold intolerance that you don’t notice you have cold intolerance, which is called “hidden” cold intolerance. What part of the body is cold when you have “hidden” cold intolerance?

A6. Abdomen.
 
There are important organs in the abdomen so the body try to warm the abdomen with priority. Hands and feet become cold because the body tries to keep the core of the body warm. On the other hand, when you have “hidden” cold intolerance, your hands and feet are warm so it is difficult to notice that you have cold intolerance, but your body temperature is low and your internal organs are cold. When the internal organs are cold, the action of the internal organs decreases, resulting in dangerous condition. If you touch your abdomen and it feels cold, you need to be careful.
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​Q7. Which is more effective to improve cold intolerance?
(A) Soaking in hot tub
(B) Soaking in lukewarm water

A7. (B) Soaking in lukewarm water
 
Soaking in lukewarm water which temperature is 38 to 40 ˚C (100.4 to 104 ˚F) for 20 minutes is recommended.
Fig. 1 shows the body temperature after soaking in hot tub. The feet became cold 1 hour after taking a bath.
Fig. 2 shows the body temperature after soaking in lukewarm water. The hands and feet became warmer than right after taking a bath.

Why does your body temperature go down quickly when you soak in hot tub?

Autonomic nervous system controls your body temperature. When you soak in hot tub, you’re your body temperature goes up suddenly so the autonomic nervous system tries to lower your body temperature. The method to lower the body temperature is making blood vessels thin and decreasing the blood flow. If the blood vessels become thin, it gets difficult to transport blood to the ends of limbs. As a result, your hands and feet become cold quickly.
 
On the other hand, in the case of soaking in lukewarm water, your body relaxes, transporting blood to the ends of limbs.
 
To improve cold intolerance, it is better to soak in lukewarm water up to your neck because there are autonomic nerves related to raising the body temperature around your neck.

If you don’t have good results with soaking in lukewarm water, warm and cold bath is recommended. Warm and cold bath is a bathing method repeating warming up and cooling down your body. The bathing method is:
(1) Soak in water of about 40 ˚C (104 ˚F) for 4 minutes. (Fig. 3)
(2) Shower your hands and feet with cold water for 15 seconds. (Fig. 4)
(3) Repeat (1) and (2) for a few times.

​Warm and cold bath is stretching of blood vessels. Soaking in lukewarm water enlarges blood vessels and showering hands and feet with cold water contracts blood vessels. Repeating this cycle strengthens blood vessels resulting in better blood circulation.