Wednesday, January 11, 2017

Healing Waters by Dr Bruce Becker

If you think the water just makes people feel 
good, you don’t know the half of it. Here’s a 
physiological explanation of the surprising and 
amazing ways the simple act of being in the 
water promotes well-being.

It doesn’t take long to notice that people in pools 
are having fun. Nor does it take long to see 
happy faces in a group of aquatic exercisers, or a 
smile replace the facial stress lines of someone
sinking into a hot tub. The feeling of relaxation 
after a vigorous pool workout is wonderful, and
unlike most other exercise experiences.

As a scientist, I’ve been impressed with the 
consistency and universality of these observa-
tions. When I began to work with Olympic 
athletes who were used to vigorous exercise 
routines, they often commented on the difference
in their post-exercise comfort from an aquatic 
exercise session vs. their normal exercise routine
. But there’s too much scientist in me not to 
wonder why these findings occur with such 
frequency and regularity. As I researched the 
medical literature,I couldn’t find much to 
explain such common events. But when I began 
to dig into the basic science literature, I did find 
information that provided some potential 

The physiology of immersion has been studied 
extensively since we prepared to put man into
space in the late 1960s because the closest proxy
to weightlessness on the planet is to be found
when immersed in water. To study the physio-
logical changes that would occur in space, it
became important to study those changes 
occurring during immersion. The physiological 
alterations were profound and led to further 
research of specific body systems. Still, most of 
this research was not translated into medical 
applications, but rather, was located in highly 
scientific physiology journals.

Even today, there’s relatively little research on 
the clinical applications of aquatic activity or 
exercise to be found in medical journals. This 
crossover from basic science into clinical
application is called translational research
and it is only beginning to emerge for aquatics.
But as more people turn to the water for therapy 
and healing, that body of evidence is growing 
daily. If the industry can capitalize on these
findings, understand and promote them
effectively, aquatics could become the next big
health craze, with the promise of helping
everything from high blood pressure
to heart failure. 
Given that the American Heart Association says
72 million Americans suffer from high blood 
pressure and more than 79 million have cardio-
vascular disease, that could be a powerful 
incentive. The nation, in turn, could save huge
amounts in health expenses if the public were 
educated about the value of aquatic activity, if 
the political powers directed public expenditures
toward pool construction to improve public 
access and the medical establishment understood
the potential value of aquatic activity across a 
wide range of clinical problems. But it must start
with us. It must start with understanding why 
water is so healing.

Finding balance

To understand why aquatics is so good for your 
health, you must first understand some basic 
physiology. Our bodies are constantly trying to 
seek a physiological balance point called 
homeostasis. This state preserves optimum 
function despite changes in position, activity, 
stress, aging or disease. The effort to find 
homeostasis is what propels most of the 
functional adaptations that occur during 
immersion in water, with some changes being 
immediate and others only after a period of time.
Like many adaptations, a cascade of other 
physiological changes occur, some sequentially 
and some concurrently.
Here’s how it works: Because water compresses
the body, it pushes blood into the deep vessels
during immersion. As the bather steps into 
deeper water, blood is pushed upward, first into
the large capacity vessels of the pelvis and 
abdomen. Then as depth increases yet further, 
blood is pushed above the diaphragm into the 
chest. With neck depth immersion, nearly three-
quarters of a quart (1 US quart=946.353 ml) of 
blood is displaced, with two-thirds of it going 
into large pulmonary vessels and one-third into 
the heart.
The heart responds to this extra volume of blood
by increasing the amount propelled with each 
beat, which is called stroke volume. At rest 
during neck-depth immersion, stroke volume 
normally increases approximately 30 percent. 
The total volume of blood propelled by the heart 
during a minute is called cardiac output, and this
also increases nearly 30 percent. That’s approxi-
mately the same increase that occurs during light
exercise, so even at rest during neck-depth
immersion, the heart is performing just as it 
would during exercise on land. At the same time
, the body senses that more blood is being
pushed into circulation,so to adjust, the arterial 
blood vessels relax without causing an increase 
in blood pressure. Thus, healthy individuals will
lower their blood pressure during immersion, 
and usually so will individuals with elevated
blood pressure (hypertension.) The magnitude
of this drop is related to the temperature of the

Usually, there’s an initial brief increase in blood 
pressure upon entering cold water and also 
extremely warm water. Maybe that’s why in the 
past, it was often stated that individuals with 
hypertension should avoid hot tubs. Many 
physical therapy texts also say that patients with 
elevated blood pressure should not undergo 
aquatic therapy. In actual fact, immersion may 
benefit such patients.

Heart and health

Patients with congestive heart failure are another
clinical population that has been counseled to 
avoid aquatic exercise or even immersion. But 
several recent Japanese and Israeli studies have 
found that for people with mild to moderate 
heart failure, aquatics may be a very useful and 
therapeutic environment. That’s because 
immersion offers a unique combination of 
benefits: It decreases circulatory resistance and 
improves heart contraction efficiency. One of 
these studies compared the effects of aquatic 
exercise with rest in a group of patients with 
moderate congestive heart failure. It was found 
that the aquatic exercise group of patients 
significantly improved in muscle function, 
walking distance, aerobic fitness and exercise 
They also experienced nearly 40 percent
improvement in their quality of life. One reason
may be that during immersion, the increased 
blood volume is pushed into deeper tissues. 
Muscle circulation then improves and there’s a 
consequent increase in oxygen delivery, which 
is useful for muscle healing or recovering from 
exercise. A study done on astronauts in training 
showed that the blood flow into their calves was
increased by nearly 250 percent at rest during
neck-depth immersion. At the same time, the 
kidneys see an increase in blood volume. 
Sensors within the heart and elsewhere interpret 
the increase in blood volume as a potential 
overload, so the body sends signals to the
endocrine system to reduce this blood volume. 
As a result, the kidneys begin their role in 
regulating blood volume through excreting 
sodium and potassium, and along with those 
ions, water. As all aquatics professionals have 
experienced firsthand, this process produces an
increase in urine volume and the kidneys also 
become slightly more efficient. In ancient Greek
and Roman times, when medications were very
limited, immersion was actually used as a way 
to treat individuals with kidney disease.
Stress is another ailment that immersion can 
help alleviate. Some of the same hormones that 
the body uses to regulate arterial function and 
tone are a component part of our body’s 
response to stress. These hormones are called 
catacholamines. During immersion, the body 
sends out a signal to alter the balance of these 
catacholamines in a manner that is similar to the 
balance found during relaxation or meditation.
Not all of the effects of this alteration are known
, but probably these changes are important in 
modifying the heart rhythm in a manner to 
mimic a relaxed state, and also in creating some 
of the feeling of relaxation that occurs following 
aquatic activity.

Exercise and endurance

The connection between exercise and stress 
reduction has been well-established, and the
work the body must do in water may be one 
reason. During immersion, compression of the 
chest wall combined with the increased blood 
volume makes it more work to breathe — 
approximately 60 percent more with water up 
to the neck. This, in turn, can lead not only to 
lower stress,but also better performance during 
land workouts.
In my experience working with Olympic level
athletes, a frequent comment was how much the 
aquatic workouts had added to their overall 
feeling of fitness. I believe what they were 
noticing is that strengthening the muscles of 
respiration had significantly improved their 
respiratory efficiency, so during a land based
workout they didn’t feel so “winded.”
If the workload increase is 60 percent during 
inactive immersion, there is almost certainly a 
much greater workload increase during 
immersed exercise. Blood and water are viscous
substances, and the force required to move 
against viscosity is related to velocity in a 
complex equation. Essentially, as the frequency 
of respiration increases, so does the work of 
displacing blood from the chest cavity to allow 
air in. The chest wall must then expand against
the compression of surrounding water. As 
consequence, deep-water exercise potentially
could be a very useful method of strengthening 
the muscles of respiration,which could be 
helpful in athletes, as well as in the rehabilita-
tion of people with respiratory weakness or 
other lung diseases.

We decided to test that possibility in astudy 
completed last year at Washington State 
University. We worked with two groups of WSU
students, 50 in each group. One group did land-
based aerobics for a 50-minute period, three 
times per week for a semester.
The other group did aquatic aerobics 50 minutes
per session three times per week. We measured 
aerobic conditioning, percent age of body fat, 
and a number of measures of respiratory 
efficiency and strength. All of the students 
increased in their aerobic fitness, all decreased 
their body fat percentages, and all improved in 
some of the respiratory measures. But only the 
aquatic students showed improvement in their 
respiratory endurance measures. We plan to 
repeat this study with more focus on higher-fit 
student athletes to see if the same effect is noted.
There is a potentially major benefit of improving
respiratory endurance because as the muscles of 
respiration fatigue, the body begins to shunt 
blood from the lower extremities up to the chest 
muscles to support respiratory effort. Obviously, 
in an athlete who is reliant upon the legs, 
robbing these muscles of blood flow to supply 
the muscles of respiration causes a decrease in 
athletic performance. A basketball player who is
getting respiratory fatigue will “hang on his 
shorts,” which can be seen often at the end of a 
basketball game. This action aids the accessory 
muscles of respiration. But if at the same time, 
the leg muscles are being starved of blood, the 
player is going to feel like his or her legs are 
“dead.” Studies have shown that exercise 
activities to improve endurance of the muscles 
of respiration actually do improve athletic 
performance, but deep-water exercise would be 
an easier and potentially more efficient means of
producing such an effect, while allowing the 
athlete to decrease stress forces upon the spine 
and lower extremities simultaneously.

Rehab and weight loss 

This latter effect occurs because of the off-
loading effects of buoyancy. At waist-level 
immersion depth, the hips, knees, ankles and 
feet have a 50 percent reduction in loading due 
to buoyancy; at mid-chest depth, there’s a 75 
percent offloading. As a consequence, this effect 
may be used to excellent clinical benefit in 
facilitating recovery from training, or 
rehabilitating from a lower extremity or spine 
injury. The combination of joint offloading, with
the improvement in deep-tissue circulation 
makes the aquatic environment very useful in 
rehabilitation. In fact, even before these effects 
were known, deep-water exercise was used to 
improve racehorse performance without 
exposing the animals to the trauma of the 
racetrack. Owners found they could nearly triple
the expected race career of a horse if they used 
aquatic training for a significant part of the 
workout regimen. In working with Olympic 
distance runners through the Nike development 
program, we tried to have about one-third of the 
training done in water, which seemed to reduce 
injuries as well as improve performance. The 
value of aquatic exercise in patients with osteo-
porosis has been controversial. The aquatic 
environment would be ideal for this group 
because of the frequent coexistence of joint 
disease and the decreased risk of fractures from 
falling during land based exercise. Many such 
patients have a fear of falling that limits their
 tolerance of a land-based walking program, an 
activity that has been shown to build bone 
mineralization and reduce osteoporosis. Most 
studies of aquatic exercise have not shown a 
useful benefit upon bone mineralization, 
however. Studies comparing regular aquatic 
exercisers with regular land-based exercisers 
have shown better bone mineralization in the 
land-based groups at nearly all ages from 
adolescence through senior groups. This does 
not mean that aquatic exercise lacks a place in 
this group of individuals. In my practice, I will 
typically start such a patient in an aquatic
exercise regimen, which has been well shown to
boost lower extremity strength and endurance, 
as well as improve balance. The combination of 
increased strength and balance skills is usually 
sufficient to enable that individual to embark 
upon a walking program safely and begin the 
bone-building process. Another controversial 
point is how aquatic exercise works for obese 
individuals. Because of the offloading produced by buoyancy, the aquatic environment seems ideal, especially in persons with decreased lower extremity strength. It has been shown that aquatic exercise is less efficient in decreasing body fat percentages than land-based programs. Even at Olympic levels of training, these athletes have a higher percentage of body fat than their track athlete peers, as can be seen readily. The swimmers have sculpted 
beautiful bodies with higher percentages of body fat,
whereas the track athletes have greyhoundslim
bodies with very, very low percentages.
Despite this concern, the value of
exercise in obese individuals is absolutely
essential, and aquatics may be a tremendously
useful method of initiating a program
and losing weight over time. While
it may not be as efficient from an absolute
standpoint, it is still effective and likely to
be better sustained because of the lower
risk of joint injury in aquatics for this group.

STRESS RELIEF During immersion, the body sends out a signal to alter the balance of a certain
type of hormone, which creates a balance similar to relaxation or meditation. 

Many of these individuals can participate
successfully for years in a group format, and
I’ve seen people whose lives were totally
changed because of such a program.

On the whole, the response of the human
body to the aquatic environment is profound.
Perhaps it is because all of us spent the initial
formative months of our lives immersed
in a warm-water pool of amniotic fluid that
we can so readily sink into a pool with
relief. Such an environment would provide
protection and the optimum conditions for
growth during this critical period.

But the combined effects of all the properties
of water, from buoyancy through
hydrostatic pressure to its thermal conductive
properties make the aquatic environment
tremendously useful and effective for health
recovery and maintenance, and recreation.

At Washington State University, we are striving 
to create a body of clinically directed 
translational research so that such an
understanding might emerge within the
public, as well as the medical profession.
We’re also trying to create a broader 
understanding of the immense value of aquatics
for high-level athletic training because the
public seems to relate to the effectiveness of
this kind of effort as well.
It is my hope and belief that in the
future, we will see a wetter, happier and
healthier world. ■


■ Broad public awareness campaigns
■ Education within the medical community
■ More active community involvement
■ Legislative advocacy
■ Promotion and dissemination of clinical
research in consumer and medical media.

This diagram shows what’s happening in the body before a person enters the water, and what happens afterward. The changes are significant, especially those involving blood flow and the heart. The deeper a person is immersed, the more the health benefits increase. At neck level, even the brain
is affected because more blood is forced upward from the lower extremities.


Negative atrial pressure
Negative pleural pressure
Flattened diaphragm
Blood pooled in abdomen,pelvis,and lower

More venous compression. Heart size
increases 30% and rate slows 20%.
Heart pumps more blood; chest wall is
compressed. Plural pressure increases.
Lungs contain more blood and body
works harder to move air. 
More blood is distributed to kidneys and brain.
The diaphragm is elevated higher during 
inspiration and expiration.
As the water level rises, the abdomen is 
compressed and more blood is forced
upward into the chest cavity.
Pelvis vessel compression occurs.
Venous and lymphatic compression begin
progressively pushing blood upward.

Neck Level

Diaphragm level

This diagram shows what’s happening in the body before a person enters the water, and what happens afterward. The changes are significant, especially those involving blood flow and the heart. The deeper a person is immersed, the more the health benefits increase. At neck level, even the brain is affected because more blood is forced upward from the lower extremities. PHYSIOLOGY AND IMMERSION Negative atrial pressure Negative pleural pressure Flattened diaphragm Blood pooled in abdomen, pelvis, and lower extremities BEFORE IMMERSION DURING IMMERSION More venous compression. Heart size increases 30% and rate slows 20%. Heart pumps more blood; chest wall is compressed. Plural pressure increases. Lungs contain more blood and body works harder to move air. More blood is distributed to kidneys and brain. The diaphragm is elevated higher during inspiration and expiration. As the water level rises, the abdomen is compressed and more blood is forced upward into the chest cavity. Pelvis vessel compression occurs. Venous and lymphatic compression begin progressively pushing blood upward. Neck Level Diaphragm level

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