Topics

The health benefits of hot springs can be divided into "direct effects" and "indirect effects".
Furthermore, the direct effects of hot springs are generally classified into (1) physical effects, (2) thermal effects, and (3) chemical effects, but in reality, these three effects work together on the body.

Physical (Mechanical) Effects

In the water, the body is subjected to water pressure, which improves the flow of blood and lymphatic fluid. Additionally, buoyancy makes the body lighter, reducing the burden on the legs and hips during aquatic exercise, and the resistance of the water adds load, strengthening the muscles.

Thermal Effects

Soaking in lukewarm water (about 38°C) activates the parasympathetic nervous system, which suppresses the functions of the nervous and circulatory systems.
Conversely, hot water (42°C or higher) activates the sympathetic nervous system, stimulating the functions of the nervous and circulatory systems.
Therefore, the temperature of the water is chosen according to the purpose of hot spring therapy and the individual's condition.

Chemical Effects

The chemical components contained in hot springs act on the body and are unique to hot springs.
For example, bicarbonate springs (baking soda springs) have an effect of suppressing stomach acid when ingested, and the antibacterial properties of sulfur springs are effective for skin diseases.

In addition to the direct effects of hot springs mentioned above, there are also significant mental effects from "relocation effects" obtained by visiting hot spring areas, which provide a break from daily life, and these combined effects bring benefits to both mind and body.