Is there a health risk to soaking your feet in hot water? These 4 types of people should be careful!

Soaking your feet in hot water before going to bed has become a "compulsory course" to reward yourself. For many people, putting your feet in a basin of hot water and feeling the warmness spread from your feet to the whole body is indeed very comfortable, so many people also say that soaking your feet in hot water can improve your health, especially when this statement is used by some commercial products, they will even more boast about the efficacy of soaking your feet in hot water.

However, don’t say that it has no effect. For many people, soaking feet in hot water even has certain health risks.

Everyone wants to soak their feet, but how to do it? It's really a problem.

Too long to read

1. Foot soaking is very comfortable, but it does not have the many benefits advertised.

2. Foot soaking is not suitable for everyone. Patients with diabetes, varicose veins and children should be careful.

3. The water temperature for foot bathing should not be too high, about 40℃ is appropriate. Too high water temperature is harmful to people with cardiovascular and cerebrovascular diseases. At the same time, too high water temperature can easily damage the sebum membrane on the surface of the foot skin, causing the stratum corneum to dry out or even crack.

4. The foot soaking time should not be too long. Each time should not exceed half an hour, because the blood circulation and heart rate of the human body will accelerate during foot soaking, and too long time will increase the burden on the heart.

5. If you are not sure about the water temperature, it is recommended to test it with your hands instead of your feet, because hands are more sensitive to temperature than feet. For patients with diabetic foot, use a thermometer to measure the temperature when washing feet to avoid burns.

Hot water foot bath

Not so magical

When soaking your feet in hot water, the peripheral blood vessels in your legs and feet dilate due to the increase in ambient temperature, and the blood flow to the skin of your feet increases. However, this change in local circulation in a short period of time will hardly have a big impact on the systemic circulation, and will not even affect the core body temperature like a bath or shower. Therefore, for healthy people, soaking your feet may not cause too much physical change, so expecting to treat various diseases by soaking your feet will not be effective.

From the diagram of blood circulation, we can see that the body circulation is composed of many blood vessels connected in parallel, and hot water foot bath will only change the local blood circulation of the lower limbs of the body at first. This change will not have much impact on the body circulation in a short period of time. Image source: hanyu.iciba.com

A search of relevant research found that the sleep-inducing effect of hot water foot baths is probably the most studied. An article published in the International Journal of Nursing Research in 2013 reviewed the results of this study from 1996 to 2005. In this experiment, 25 healthy middle-aged and elderly subjects were found to have a sleep-inducing effect by hot water foot baths.

The main conclusion of this paper is that for healthy people, a low-temperature, short-term foot bath can help sleep, but it is not very effective for the elderly and people who have poor sleep. The study explains the relationship between foot bathing and sleep aid through the "distal-proximal temperature gradient", or DPG (distal-proximal skin temperature gradient): the distal temperature is high and the core temperature is low (in simple terms, the hands and feet are warm), that is, when the DPG is large, the sleep quality is good.

This may be because warm skin temperature can stimulate the anterior hypothalamus, which is the sleep regulation area. The human body's core temperature has a rhythmicity, which is high during the day and low at night, so it is easy to fall asleep at night. When people age, their core temperature at night gradually rises and loses its rhythm, resulting in prolonged sleep latency and early awakening.

However, this study does not recommend long-term high-temperature foot baths, because this will increase both distal and core body temperatures, reduce DPG, and be detrimental to sleep. This article recommends a hot water temperature of 40 degrees and a foot bath time of 20 minutes. Other studies have shown that the relationship between skin surface temperature and sleep latency is related to age and a history of insomnia.

Not for everyone

However, for people with underlying vascular diseases, soaking feet for a long time and at too high a temperature will cause local vascular dilation, resulting in insufficient effective blood volume in the body. For them, soaking feet still has certain health risks. Therefore, soaking feet is not suitable for everyone.

1. Diabetic patients

Diabetic foot is one of the most common complications of diabetes patients and one of the main causes of disability and death for many diabetic patients. Searching for "diabetes, foot bath" and other terms will show many Chinese articles supporting foot bath treatment for diabetic foot. The basis of these articles is nothing more than promoting blood circulation, unblocking meridians, and nourishing nerves.

However, after a detailed investigation, you will find that the common feature of these studies is that they only observe clinical cases but have no theoretical basis. In terms of patient selection, they are generally based on subjective symptoms rather than the degree of vascular disease. This type of research that only uses patients' subjective feelings as clinical evidence is too unreliable.

Diabetes damages the endothelium of the blood vessels in the feet. The blood vessels can no longer dilate or contract due to temperature changes. So can hot water help blood flow and achieve the purpose of "activating blood circulation"? Obviously, it is impossible, and cold water will naturally not make the condition of the blood vessels worse.

On the contrary, the skin of diabetic foot patients is generally more fragile, and the peripheral nerves of the feet are not sensitive to temperature due to problems. Normal people feel that the water temperature is very hot, but they cannot feel it. Therefore, hot water soaking is particularly prone to burns. Moreover, once diabetic foot patients are burned, even a small blister, if they do not seek medical treatment in time, it may lead to foot infection and ulceration, and severe cases may even require amputation.

2. Patients with varicose veins or thrombosis

Varicose veins are a type of blood vessel swelling caused by blood congestion due to poor venous blood return. Varicose veins are generally common in the front parts of the limbs, such as the hands and feet, because these places are farthest from the heart and the blood flow is slow, which is a venous return problem.

Can soaking your feet in hot water speed up the blood flow? Actually, not really. The main cause of varicose veins is venous valve insufficiency. The increase in temperature cannot improve the function of venous valves, but will only increase local blood flow. This increase in local blood flow will not change the speed of venous return, but will increase the burden of venous return.

Normal venous valves can help the veins return blood to the lower limbs (pictured above), while patients with varicose veins mainly show dysfunction of venous valves (pictured below). In this case, increasing local blood flow will increase the burden of venous return. Image source: hp-loksbergen.be

3. Patients with skin diseases such as tinea pedis

Many people believe that soaking feet can alleviate the symptoms of tinea pedis, but this is actually a misunderstanding.

Tinea pedis is a fungal infection that requires antifungal treatment. Many tinea pedis patients feel more comfortable after washing with hot water because of the itching, which can kill bacteria. In fact, this method of using heat to relieve itching often has no effect. After soaking, the affected area will not only become more itchy, but also blisters may appear. Hot water dilates the capillaries in the feet, which may lead to secondary bacterial infection.

There have been reports of tinea pedis patients being infected with erysipelas by soaking their feet in warm water. Soaking feet in hot water can make things worse for wounds that have already broken due to skin diseases. The wound must be left open to dry and ventilate according to surgical treatment principles.

4. Children

As we all know, a very important structure of the human foot is the arch. Its main function is to cushion the shock to the human body during walking, running and jumping, and to protect the blood vessels and nerves in the sole of the foot from compression. It can also protect the brain, spine, and organs in the chest and abdominal cavities. It is the "shock absorber" of humans.

As shown in the picture, during the early childhood, the baby's arch has not yet formed, the bones and joints are very elastic, and the fat accumulated on the soles of the baby's feet will also make the arch less obvious.

Image source: weather.com.cn

This structure begins to form in childhood, so it is very important to ensure the healthy development of the baby's arch. If children are frequently soaked in hot water, it will affect the function of the nerves and blood vessels in the feet. Frequent soaking or scalding will cause the ligaments on the soles of the feet to become loose, which is not conducive to the formation and maintenance of the arch. In the long run, it will increase the risk of flat feet.

Author: Vermicelli

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