Watsu and Water

What is the ideal water temperature for Watsu?

There is none. Due to differences in metabolic rate, thickness of subcutaneous fat layers, and personal preferences, no one temperature suits every receiver. Air temperature, wind, and sunlight also have an effect on how water temperature is experienced. The receiver’s sense of warmth is the key: she will want to feel warm, but not hot. If water is cooler than skin temperature (94° F.) the body senses cold. Water heated above internal core temperature (98.6° F.) is fine for a short while in a hot tub, but feels too hot for an hour’s immersion. The range then of 94° -98.6° F. will work for most people.

How can I tell if the water is too hot?

Be alert to signs of overheating: flushing, sweating, headache and dizziness. Flushing is a sign of increased capillary flow to the skin surface. The body's intent is to lower the skin's temperature by flooding cutaneous capillary beds, having the blood absorb heat, and then carry it away to the interior. Sweating is meant to cool the skin via evaporation: as water converts to its gaseous state a great deal of heat energy is lost off the skin. Evaporation normally cools very effectively, but not so well on hot days in the pool, owing to an already high air temperature and humidity and the fact that most of the body is underwater anyhow! Thus the sweat beads on the exposed skin and dehydration occurs, resulting in headache.

What should I do if the pool is too hot?

1. We give a shorter session, or avail ourselves at intervals of dips in a cold plunge. Stand under a cold shower.
2. Watsu slowly. The quicker a person is watsued through warm water, the more fast moving (hot) water molecules collide against the skin, thereby generating heat. It is the converse of the phenomenon known as "negative wind chill factor", in which a person standing in a cold wind gets colder than if the air were stationary.
3. Hold body parts out of the water.
4. When working in sunlight, wear a hat and sunscreen, keeping to the shade. We keep partner’s face in the shadow of our hat. Other options are to cover her face with a fig leaf (at Harbin Hot Springs) or a damp washcloth/
5. Break to share a drink of water from a poolside bottle. Pour water over partner’s head.

How can I tell if the water is too cold?

Cold produces shivering and goose bumps. These two homeostatic mechanisms are designed to produce and retain body heat. Shivering is rapid involuntary muscular contraction, which like all muscular contractions, generates heat. Goose bumps are the result of tiny muscles, (the erector pili) one for every hair, contracting to erect the hairs. This is supposed to help them better trap air next to the skin where it can be warmed by the heat the body normally radiates away. If and when we were a hairier species, this must have worked fine, but doesn't do much these days. If our client is shivering, covered with goose bumps and turning blue, science tells us we can safely assume she is too cold to be watsued!

What should I do if the water is too cold?

1. Give a shorter session or get into some hot water at intervals.
2. Watsu at a quicker tempo. The heat energy present in the water molecules will be brought into greater contact with partner.
3. Hold partner close, so that our body heat warms her.
4. If working outside in cool air, adapt a more submerged style to avoid the chilling effects of evaporation off exposed skin.
5. Believe it or not, wetsuits are a viable option for both giver receiver when there is no other option. They come in thin, flexible fabrics. The reduction in skin on skin contact is initially safer for some clients.

What physiological effects does the warmth of water have during a Watsu?

1. Promotes muscular relaxation.
2. Increases body temperature when water temperature is higher than skin temperature. Also, as skin temperature increases, cutaneous vasodilation occurs
3. Causes loss of sense of body shape and boundary when water temperature approximates skin temperature.
4. Reduces pain sensitivity. The warmth "distracts" the pain, with sensory input which travels on nerve fibers larger, faster, and with a greater conductivity than the pain fibers.
5. Decreases muscle spasm.
6. Prepares connective tissue for stretching.
7. Increases peripheral circulation in temperatures greater than 93° F. (34° C).

 

Some "cool" things to know about water’s thermodynamic properties.

1. Water retains heat better than any other liquid, except ammonia, and 1000 times more than an equivalent volume of air.
2. Water conducts heat 25 times faster than air. So, a submerged body can absorb or lose heat quickly. Pool temperature is therefore critical, especially to certain populations, such as the thin and the elderly: a little too hot or cold and the receiver is soon affected. Heat transfer to an immersed body occurs mostly through conduction and convection. Heat loss from an immersed body is mostly through radiation and convection.
3. If water temperature exceeds the temperature of the submerged body, the system equilibrates to a different level. The submerged body warming through transference of heat energy from the water, and the water cooling through loss of heat energy to the body. Thus, when a therapy pool is really crowded it gets cooler as the bathers absorb its heat.

What is hydrostatic pressure?

Just a fancy name for water pressure--the pressure that water exerts on objects immersed in it. Like air pressure, hydrostatic pressure is equal in all directions at any given point. However, hydrostatic pressure is greater than air pressure. Because water is heavier and denser than air, we find the seas beneath the skies.

Does it increase with depth?

Yes. Hydrostatic pressure increases with depth, as the water above weighs upon the water below. One doesn't have to live in a multi-story apartment building (less water pressure on the higher floors) or go scuba diving to realize this: four feet below the surface one feels the added pressure on the outer surface of the eardrums. The pressure of the earth’s atmosphere is also an important contributor to the total force from immersion.

What effects does hydrostatic pressure have during a Watsu?

1. Helps stabilize unstable joints, making Watsu quite safe for injuries when administered conservatively.
2. Provides more resistance to the expansion of the ribcage and abdomen in breathing, thereby strengthening the diaphragm and intercostal muscles. Giving Watsu is good for our lungs!
3. Compresses all soft tissues, enhancing lymphatic return. Normal lymphatic pressure is a negative pressure system, so that even minimal water depth immersion exceeds the lymphatic pressure.
4. Aids venous return in the legs. A body immersed to a depth of 48 inches is subjected to a force equal to 88.9 mm HG, slightly greater than diastolic blood pressure. This is the force that aides the resolution of edema. Giving Watsu is good for our legs!
5. Displaces approximately 700 cm³ of blood from the extremities and abdominal vessels into the great veins of the thorax and into the heart on immersion to the neck. This causes a significant increase in right atrial pressure, stroke volume, and cardiac output, resulting in bradycardia. This is the dive reflex. There is an effect on systemic vascular resistance, which drops dramatically, and on muscle circulation, which increases several -fold." Drop low and work in the "crocodile style".
6. Increases inter-thoracic blood volume. Water pressure on the external wall of the ribcage exceeds that of the air within the lungs, resulting in a negative air pressure system. This raises the volume of air within the ribcage.
7. Renal Response to Immersion

Natriuresis--increased sodium excretion

Kaliuresis--increased potassium excretion

Diuresis, that is increased urine excretion, is stimulated by immersion. An increase in central blood volume (enhanced venous return and negative pressure breathing within the lungs) plus increased right atrial pressure respectively suppress ADH and stimulate ANH.

Why do people weigh less in water than on land?

As explained earlier, pressure in a fluid increases with depth. Therefore, the force exerted on the bottom of a submerged object is greater than that on its top, pushing the object upward. Buoyancy is the name given that upward force acting on objects immersed in water. As Archimedes discovered soaking in his bath, the upward thrust equals the weight of the fluid displaced. Eureka!

How does buoyancy affect the Watsu giver?

1. Buoyancy is termed assistive as it aids holding partner at the surface, supportive in lateral movements, and resistive in movements that would lower partner in the water. Without the buoyant force, Watsu would be impossible. "Let the water do half the work." With the water we form a two member team. Avoid over-supporting. In the words of Obi-Watsu-Kanobi, "May the buoyant force be with you!"
2. Buoyancy is what makes body mechanics so different in water from on land. Even as it takes weight off our joints, it ungrounds and reduces stability when standing. Wearing ankle weights helps counter these negative effects of buoyancy.
3. When a practitioner sinks low in the water during a Watsu, her body bears very little weight. Sunk to the level of the occiput, only 1% of body weight is borne on the legs. Therefore, to reduce effort and to rest when fatigued, drop low in the water, "crocodile style."

How does buoyancy affect the Watsu receiver?

1. Muscular relaxation. With gravity counterbalanced, our muscles are freed from their continual work of holding us up, and have the opportunity to relax completely.
2. Loss of muscle tone. According to James McMillan, the developer of the Halliwick method, muscle tone is influenced by proprioceptive input stimulated by gravity. In other words, tone is a function of weight. After the effects of weight (gravitational force) have been neutralized by 15 minutes of immersion, a person’s tone automatically decreases. This change in tone lasts for up to 1.5 hours after leaving the pool.
3. Joint decompression. As muscles relax and joints are relieved of their weight bearing function, they decompress. Movement becomes freer and with less pain in the case of injuries. The need for splinting and guarding decreases.
4. Sense of lightness. The receiver notices that she is easily supported and moved by the giver, and feels light. This is usually a positive experience, sometimes evoking associations with childhood and infancy.
5. Reduced oxygen requirements. Dr. Tcharkovsky, the Soviet pioneer researcher into water birth, has established that in the nearly weightless state one achieves immersed in water, the body's oxygen requirements are dramatically lowered, making possible the accelerated growth of premature babies (His own, for example). Relating this to Watsu, there is a tendency for the respiratory rate to decrease, enhancing the inducement of a calm, trance state.

Why do some people float and others sink?

Some people float so effortlessly that even when pushed underwater they bob up quickly. Others require constant effort to maintain at the surface. Whether a person floats or sinks is unrelated to their weight on land. A person's buoyancy in water is determined mainly by the proportion of fat to overall body weight. Ever notice how oil (fat) rises to the surface in a bottle of salad dressing? This is because fat is lighter than water, and in the body, lighter than muscle or bone. Women tend to be lighter in water than men, as they have breasts and an overall thicker layer of subcutaneous fat. Men tend to develop bigger muscles and denser bones.

Are women always lighter than men?

No. A 95 pound female marathon runner, all muscle and sinew, though not that difficult to hold up in a Watsu, would sink more readily than a roly-poly 250 pound male sumo wrestler, who would float but be cumbersome to move sideways.

What is specific gravity?

Just another way of talking about floaters and sinkers. A body's specific gravity is the ratio of its weight to that of water. The higher this ratio, the heavier a body is in water. Water has a specific gravity by definition equal to 1 at 4° C. The body’s density is slightly less than that of water, averaging 0.974, men with a higher density than women. Lean body mass (bones, muscles, organs, connective tissue) typically has a specific gravity of 1.1 (sinks); fat of 0.90 (floats).

Why do the legs sink?

Different parts of the body have different specific gravities or densities. Long, well-muscled legs with little fat have a high specific gravity and do indeed sink.

Why do some heads float and some sink?

Remember, each body segment has its unique specific gravity. Like legs, torsos and arms, heads can go either way. Brain tissue is fatty and 85% water, counterbalanced by the numerous bones of the cranium and face. Long loose necks seem to allow heads to sink more readily than short, tight ones.

Name the capital of Venezuela.

Caracas.

Why does the chest float and the pelvis sink?

The center of buoyancy (COB), resides in the midchest. With the residual volume of air in the lungs that is never expelled, combined with air that is inhaled, this is the lightest part of the body. The center of gravity (COG) is defined as that point, around which in all directions the weight is equal. It lies in the region of the pelvis, slightly higher in men than women because of their heavier upper body musculature. In water, the COG wants to align itself vertically beneath the COB. Thus, the chest rides high as the legs and hips drift downward.

 

How do I work with sinkers?

1. In 1st Position as the arm supporting the pelvis tires, shift it to under the knees, drawing the legs closer in, compacting the weight and allowing the hips to drop comfortably down.

2. When in the folded up Accordion position described above, shift the entire body sideways so partner’s hips are in front of our navel instead of off to the side.

3. Hold the body snug whenever possible.

4. Use positions in which one or two legs are draped over our shoulders or wrapped around us, such as Far Leg Over. This brings the person's COG more nearly in alignment with our own center line of gravity as do 1.-3. above. It also shifts effort from our arms to our back, which is far stronger.

5. Drape partner’s legs over our own legs in the Open Saddle or Side Saddle. Easier on the back.

6. Travel quickly through the water in transitions and rotations if possible. This keeps sinker legs off the bottom and sustains the lower back within an acceptable range of extension.

7. We don’t hesitate to use our own thigh in transitions to provide support.

8. In Stillness, we brace the elbow of our arm supporting the hips against our side.

1. In Undulating Spine, take the force from the legs.
2. Keep it simple: we don’t tire ourselves, moving out of uncomfortable positions sooner rather than later.

9. Use flotation devices. "A man should float like a woman," sayeth Alexander. The floats of choice are made of neoprene (wetsuit material) with velcro strips and can be cut to different sizes. They wrap around the thighs, calves, ankles or even the neck and waist to fine tune partner’s buoyancy. The "noodle", in vogue in pools everywhere, can serve as a "Third Arm" supporting under one or both knees. With either kind of float, the sensory nerves adapt in a few minutes and the receiver is no longer aware of their presence.

Why is it harder to move someone through water than through air?

Friction between water molecules creates resistance to movement. This internal friction in any fluid is called viscosity. The molecules tend to cohere to each other and adhere to the body. The molecules at the surface cling to each other with a force known as surface tension. Cohesion, adhesion and surface tension all come into play in Watsu. In addition, an object moving through water is subject to drag, depending on the speed of the movement and how streamlined the object. A large person is less streamlined than a small person and will occasion more drag. Moving partner slowly through the water creates streamline flow in which all layers of water move at the same speed parallel to each other. Drag is reduced. Moving partner quickly causes turbulence, in which eddies form as well as a low pressure area in the wake behind the movement, both of which increase drag.

Can viscosity and drag work for me in Watsu?

1. Yes! They add power to stretches that move through the water.
2. Yes! They hold the legs and hips near the surface in transitions.
3. Yes! They bring the body in close to us on turning movements.

© 1996 Alexander Georgeakopoulos

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