Warmth and acupuncture points on the feet: Tradition and modern research

Why are feet sensitive to touch and warmth?

The skin of the feet contains sensory endings that detect different stimuli. Touch, pressure and temperature are processed through different sensory mechanisms. [1]

Placing a foot on a surface brings it into contact with that surface’s shape, texture and temperature. Several sensations can therefore occur together. Describing what we feel is a useful first step towards understanding the stimulus.

What is KI1 – Yongquan?

KI1, called Yongquan, is a point in the traditional acupuncture system on the sole of the foot. WHO locates it in the depression that becomes more pronounced when the toes are flexed. [2]

A standardised location gives practitioners and researchers a shared reference. The point belongs to the so-called kidney meridian in traditional terminology. That name identifies its place within the traditional system.

Are acupuncture points and reflexology zones the same?

No. Acupuncture uses points organised within a traditional meridian system. Reflexology has its own maps of foot zones associated with other parts of the body. The two maps are not interchangeable. [2, 3]

When looking at a foot diagram, first check which system it represents. A caption should explain whether it shows an acupuncture point or a reflexology map. This makes traditional illustrations easier to understand.

How does warmth or touch become a sensation?

Sensory cells and nerve endings convert a physical stimulus into electrical activity. The nervous system processes this information as temperature, touch or pressure. This is a sensory mechanism. [1]

That is why warmth and pressure at the same spot can feel different. The stimulus is detected in the skin, while the resulting sensation involves processing by the nervous system. This provides a biological explanation for what we feel on contact with a warm surface or a gentle touch.

Does warmth act in the same way as needles or pressure massage?

These are different stimuli. In acupuncture, a needle penetrates the skin; in pressure massage, mechanical force is applied; with warming, the thermal conditions change. Moxibustion is a traditional practice using heat from smouldering material. [3, 6]

Applying different methods to the same area does not make them equivalent. A study of needles therefore cannot be presented as a study of a heated platform. Warmth alone also does not mean that a device performs pressure massage.

Do I need to place an acupuncture point precisely on the platform?

For BioWave, follow the contact surfaces and the instructions for foot placement. The brochure describes seated use with clean, dry, bare feet; it does not require locating KI1. [5]

The device’s instructions provide the practical reference for placement and settings. No acupressure technique is required. If you need to reposition your feet, first switch off the output as instructed.

Does feeling more heat mean a greater effect?

The sensation of warmth alone does not establish the dose or a health outcome. Comparing conditions requires the actual temperature, duration and application site. How something feels and how it is measured are different kinds of information.

The BioWave brochure recommends checking skin and comfort and states that strong heat and sweating are not the goal. A higher setting is therefore neither a competition nor a required step. The time limits in the instructions apply even when use feels pleasant. [5]

Does a reflexology map prove a connection to internal organs?

No. Assigning foot zones to organs is part of reflexology tradition; the claim that treating a zone heals its associated organ has not been established. [3]

A biological explanation should stay with what was actually observed: the stimulus, nerve signalling or a measured local response. A name such as “kidney point” does not demonstrate improved kidney function. The brochure’s description of feet as a “second heart” is a traditional analogy. [5]

How do researchers study these mechanisms?

During controlled warming of skin, Minson and colleagues investigated the contribution of local nerve reflexes and nitric oxide to the skin blood-flow response. [4]

This experiment helps explain the physiology of a thermal stimulus. It did not test a reflexology map or KINGRAY BioWave. Identifying a mechanism also does not establish that a different stimulus with different parameters will produce the same result. Warmth and blood vessels are discussed in a separate article in the series.

What does this mean for comfortable BioWave use?

Start by understanding the controls, foot placement and restrictions in the instructions. Remain comfortably seated and awake, check your skin and stop if use feels unpleasant. Do not stand on the platform with your full weight. Choose duration and intensity from the current instructions, rather than the settings of a scientific study. [5]

The brochure prohibits use, among other circumstances, during pregnancy, with a pacemaker, and with metal implants or stents. If you have reduced sensation, unexplained pain, swelling or damaged skin, check suitability with a clinician first; this brief overview does not replace the model’s full restrictions. [5]

KINGRAY BioWave is a wellness device for relaxation at home. Describing mechanisms in this article is not a claim that the device diagnoses or treats disease.