By Bruce E. Becker, MD
People have enjoyed warm-water immersion long before written history. In fact, many of the earliest habitation areas were established around natural hot springs, which allowed residents to take advantage of the benefits they had to offer. However, despite these facts, it is surprising that still today many people make little use of the warm-water environment for health advancement and preservation.
In recent years, a considerable amount of research has gone into assessing the impact of warm-water immersion and aquatic exercise on health. For instance, warm water immersion has been found to produce a dramatic impact on the human autonomic nervous system (ANS) (i.e. involuntary nervous system), the component of the central nervous system that controls cardiovascular and gastrointestinal function, blood flow and distribution, muscle tone and even a great deal of brain activity. The ANS has two components: the sympathetic system and the parasympathetic system.
The sympathetic system
This system creates what is commonly termed the ‘flight’ or ‘fight’ mechanism. It is evoked during fear and prepares the body for combat and stress by raising blood pressure and heart rate, increasing muscle tone, and facilitating intense brain focus on the causes of that fear—be it a rattlesnake or an enemy combatant. It is also part of the central nervous system (CNS) that is in constant overload during post-traumatic stress disorder (PTSD).
The parasympathetic system
This system becomes dominant during states of relaxation, which facilitates digestion, lowers heart rates and blood pressure, and allows the brain to engage in a wide range of creative thought. Warm water immersion causes a dramatic down regulation of the sympathetic system, allowing the two autonomic components to come into balance.
The benefits of warm water immersion
Various studies have shown a significant, positive autonomic effect during warm water immersion in both young and older individuals. The noted effects are parallel to the findings seen during meditation and after a period of quiet relaxation.
Warm water immersion has also shown to reduce anxiety. During this relaxed state, the brain is disengaged from momentary concerns and stresses. Memory functions improve, free-associative linkages are increased, which then facilitates creative thought processes. In fact, Winston Churchill was known to take long, hot baths on a daily basis. These baths had to be kept at a particular temperature and were measured by a thermometer. He was also known to dictate and take meetings from the bathtub. It is believed that his creativity was due in part to the warm water immersion.
Immersion in water of any temperature produces buoyancy, which serves to off-load joints, reduce loads on the spine and intervertebral discs, and increase peripheral circulation as well as reducing the heart rate. However, the unique effects of warm water add to the feeling of relaxation and well-being with a typical reduction in pain, if present, and a further significant decrease in blood pressure. These effects can be beneficial in healthy people and very valuable to those suffering from health problems, such as heart disease, arthritis, anxiety disorders and depression.