Excerpts from the book Sweat, by Mikkel Aaland
Sitting in a sweat bath could be the most vigorous activity you've had all day.
The heat  produces an artificial "fever" and urges every organ of
the body into action. While outwardly relaxed, your inner organs are as active
as though you were jogging or mowing the lawn. At the same time, you are being
cleansed from inside out by the skin, your body's largest organ and its excretion,
sweat.
The oldest know medical document, the Ayurveda,
appeared in Sanskrit in 568 BC and considered
sweating so important to health that it prescribed
the sweat bath and thirteen other methods
of inducing sweat. Throughout history physicians
have extolled the medicinal value of the
sweat bath in its various forms such as the
Finnish sauna, Russian banai, Islamic hammam,
or the American Indian sweatlodge. Today,
enthusiasts claim that beyond being relaxing
the sauna gives relief from the common cold,
arthritis, headaches, hangovers and "just
about anything that ails you." Even
if these claims are somewhat exaggerated,
medical evidence shows that bathing in temperatures
of 9O degrees C (192 degrees F) has a profoundly
beneficial effect on a healthy body.
Sweating
Sweating is as essential to our health
as eating and breathing. It accomplishes
three important things: rids the body of
wastes, regulates the critical temperature
of the body at 37 degrees C (98.6 degrees
F), and helps keep the skin clean and pliant.
Many people, in this sedent
 ary age, simply
don't sweat enough, making sweat bathing
particularly desirable during these times.
Antiperspirants, artificial environments,
smog, synthetic clothing, and a physically
idle lifestyle all conspire to clog skin
pores and inhibit the healthy flow of sweat.
These detrimental effects are reversed in
a sweat bath.*
[*The physiological effects of different
sweat baths are not the same, due to variations
in heat and humidity. For example, the body
sweats more profusely in the hotter (80-100
degree C) and drier (15-25%) atmosphere of
the Turkish bath, where moisture on your
body is often merely condensation. The length
of time spent in the sauna differs from time
spent in other types of sweat baths. In this
section, results peculiar to the sauna are
noted.]
When you lounge in a sweat bath, heat sensitive
nerve endings produce acetylcholine, a chemical
which alerts the 2.3 million sweat glands
embedded in the skin. But not all of them
respond. The aprocine sweat glands, located
in the pubic and arm pit areas, are activated
only by emotional stimuli. They carry a faint
scent whose purpose is believed to arouse
the sex drive.
Nevertheless, the eccrine sweat glands,
by far the most abundant, respond to heat.
During a 15-minute sauna, about one liter
of sweat is excreted, depending upon the
individual. (Normal daily rate ranges from
.5 to 1.5 liters.) Eccrine sweat is clear
and odorless; any odor is only created by
the presence of bacteria. One of its chief
functions is to cool the body by evaporation,
although there are also eccrine glands on
the palms of your hands and soles of your
feet which react to emotional stimuli. Like
the baseball batter who wets his hands for
a better grip, it is believed these sweat
glands were intended to provide us with a
good grip on clubs, rocks or vines when our
survival often depended upon them. Sweat
glands on the feet provided greater traction
when it came time to run.
A third kind of sweat, called insensible
perspiration, originates inside and works
its way through blood and other cells to
the surface of the skin. Even without a sweat
bath, approximately a liter of insensible
perspiration evaporates each day.
A modified type of sweat gland is the milk-producing
mammary gland. Some mothers in Finland believe
the sauna encourages the breast's ability
to produce milk, although this hasn't been
established scientifically.
Sweat also has the function of being a
judicious garbage collector. During a 15-minute
sauna, sweating can perform the heavy metal
excretion that would take the kidneys 24
working hours. Ninety-nine percent of what
sweat brings to the surface of the skin is
water, but the remaining one percent is mostly
undesirable wastes. Excessive salt carried
by sweat is generally believed to be beneficial
for cases of mild hypertension. Some mental
hospitals use saunas in their rehabilitation
programs to pacify patients.
A metabolic by-product, urea, if not disposed
of regularly, can cause headaches, nausea
and, in extreme cases, vomiting, coma and
even death. Sweating is such an effective
de-toxifier that some physicians recommend
home saunas to supplement kidney machines.
Sweat also draws out lactic acid which causes
stiff muscles and contributes to general
fatigue. Sweat flushes out toxic metals such
as copper, lead, zinc and mercury which the
body absorbs in polluted environments.
Skin
Because it eliminates, the skin is sometimes
called the "third kidney." It is
far more complex than the kidney or any other
organ except the brain. It is composed of
blood vessels, nerve endings, vessels for
carrying Iymph, pigmentation, oil glands,
hair follicles, cells that waterproof and
deny entry to bacteria and, of course, the
tubular, coiled sweat glands. It is so important
that death by accumulated poisons occurs
in a matter of hours if the skin, and its
sweat passages, are smothered.
A Finnish doctor wrote: "The best-dressed
of foreigners can come into a doctor's office,
and when his skin is examined, it is found
to be rough as bark. On the other hand, as
a result of the sauna, the skin of any Finnish
worker is supple and healthy." Properly
cared for skin is better able to resist eczema,
athlete's foot, pimples and blackheads.
Furthermore, combining sweat bathing and
brushing with a loofa or rough brush removes
flakes of dried skin cells that accumulate
on the epidermis. If allowed to remain, they
can clog sweat pores and oil passages and
result in dry, flaky skin.
In conjunction with the sweat bath exercise,
supplemental dosages of vitamins B2 and E
help keep skin fresh. Cayenne pepper, ginger,
peppermint are notable herbs which, when
taken internally, promote sweating and healthy
skin.
(An interesting note: the ability of lizards
and snakes to shed old skins has fascinated
many primitive societies. Some believe that
if they could shed their old skins and acquire
new ones, they could renew their youth. During
some ceremonies, participants don the skins
of animals or other human beings in a symbolic
gesture of eternal youth.)
Heating and Cooling the Inner Body
Marvelous things happen beneath the skin
in the heat of the sweat bath. The capillaries
dilate permitting increased flow of blood
to the skin in an attempt to draw heat from
the surface and disperse it inside the body.
The bather's skin becomes cherry red. The
heart is pressed into a faster pace to keep
up with the additional demands for blood.
Impurities in the liver, kidneys, stomach,
muscles, brain, and most other organs are
flushed out by the faster flow of juices.
The skin and kidneys filter the wastes, excreting
them in sweat and urine.
Some researchers claim that the rapid flexing
of the heart and blood vessels in the heat
of the sweat bath is a healthy exercise that
puts little more strain on the heart than
strolling on level ground. The increased
capillary volume, they say, keeps blood pressure
normal. Other medical people, however, qualify
their commendations. One Finnish study observed
that whereas blood pressure of healthy persons
remains approximately normal in a sweat bath,
there occurs a marked reduction of pressure
in persons suffering from high blood pressure.
However, this effect is only transient, and
the original condition returns soon after
the sweat bath.
American doctors commonly recommend that
elderly people and persons with heart problems
should avoid sweat bathing. Finnish and German
doctors feel otherwise. Perhaps this difference
of opinion arises from the fact that the
Germans and especially the Finns are more
familiar with sweat bathing.
While the surface temperature of the skin
may rise as much as 1O degrees C, inner temperature
increases up to 3 degrees C. This is the "fever" that
Hippocrates and generations of medical people
after him sought, and is created as one reclines
in a sweat bath! Of course it is unlikely
that "every disease" can be cured
by fever, but it is common knowledge that
many bacterial and viral agents do not survive
well at temperatures higher than normal body
temperature. It is also possible that damaged
cells repair themselves quicker in fever
conditions due to the increased metabolic
rate. Recovery from illness then comes easier
and quicker.
The inner temperature rise also affects
the function of important endocrine glands,
the pituitary in particular. Located in the
bottom center of the brain, the pituitary
is known as the master gland because its
hormones regulate both metabolism and the
activity of other glands such as the thyroid,
adrenal, ovaries and testes. Urged by the
heat, the pituitary accelerates the body's
metabolism and affects the interplay of several
of the body's hormones. Some people have
gone as far to say that sex drive is increased
and growth stimulated in the sauna bath.
The oxygen needs of the body increase by about 2O percent so the lungs, another
important eliminator of body wastes, join in the body's quickened pace. (The
lungs' rapid exchange of carbon dioxide for oxygen is hindered in some sweat
baths. In high humidity water condenses on the tiny alveoli where this exchange
takes place and breathing may be slightly more difficult. On the other hand,
if the air is too dry, as occurs in many American saunas, mucous membranes
may become dry and damaged.) Clogged respiratory passages are opened by heat,
giving relief from colds and other minor respiratory problems. Sweat bathing
is not recommended for those suffering from pneumonia or other acute respiratory
diseases.
When the bocly is slowly cooled, the effects
of heat are reversed--the heart calms, sweat
pores close, dilated blood vessels contract
and body temperature returns to normal. (The
German Sauna Society recommends a warm foot
bath to re-open closed blood vessels.) On
the other hand, abrupt cooling brought on
by a plunge into snow or icy water creates
a more dramatic effect. For this reason,
people with weak constitutions should avoid
rapid cooling. Vessels near the skin's surface
contract, but since the skin's metabolism
returns to normal slower than the circulatory
system, wastes accumulate that are normally
washed out by the blood. Local vasodilators
are then stimulated and blood rushes back
to the skin's surface. The heart continues
to beat vigorously and you may experience
psychedelic flashes bouncing across your
retina from the increased adrenal activity--an
unforgettable experience! Goose bumps sometimes
appear, a phenomenon reminiscent of the time
when our prehistoric ancestors possessed
a shaggy pelt of hair. Goose bumps extended
the hair, making it thicker and giving more
insulating power against cold or protection
from attack. The swift transition from hot
to cold stimulates the kidneys and usually
creates the desire to urinate.
The typical body is 6O% water by weight
and any pounds lost at this point will be
promptly regained. (However, sweat baths
have an indirect effect on weight loss--see
appendix.) As you can imagine, the combination
of sweat bathing and cooling conditions the
body, and a well-tuned body is more resistant
to colds, disease and infection. In cold
weather, the warm glowing feeling lingers
for hours, while in hot climates the body
seems cooler than before the sweat bath.
(See chapter 3.)
Positive Effects of Negative Ions
Physiologically, the presence of negative
ions in a sweat bath is as important as the
heat. The discovery of negative ions in certain
types of saunas a few years ago became headline
news in Finland. Until then, the healing
power of the sauna was attributed to relaxation
and increased circulation. Now, negative
ions add startling new possibilities.
Since the early 1950s scientists have suspected
that ions play an important role in how the
body functions and, consequently, in how
we feel. Research has shown that an abundance
of negative ions ln the air we breathe is
highly beneficial, while a lack of ions or
a higher ratio of positive to negative can
cause physical harm. The role played by ions
in everyday life has become intensely topical
among researchers in the medical profession.
An ion is simply a molecule with an electric
charge, either positive or negative. Ionization,
or ion formation, occurs when enough energy
acts on a molecule to cause it to discharge
an electron. Because electrons carry a negative
charge, the molecule stripped of an electron
has a greater positive charge and becomes
a positive ion. The lost electron scoots
around loose until it attaches itself to
another molecule which causes the new molecule
to become negatively charged--a negative
ion.
Radioactive substances in the earth's crust
and cosmic rays cause most ionization. But
fire, crashing water (like water falls and
surf), and plants during photosynthesis can
produce negative ions as well. Europeans
take ion depletions seriously and simple
negative ion generators have been installed
in many businesses, banks, hospitals, and
passenger cars and even airliner cockpits.
Furthermore, in this country, Europe and
the Soviet Union, negative ion therapy has
been used in treatments to help burn victims
heal faster, to cure respiratory diseases,
to rid the body of general infections, and
even to check the spread of some cancers.
Conversely, scientists have found that
if the air is charged with too few negative
ions and too many positives, we become anxious,
fatigued and tense. This condition is known
as "pos-ion poisoning," and often
occurs as the result of weather disturbances,
central air conditioning, smog, and driving
too long within the confines of an automobile.
Pos-ion poisoning has, in fact, been linked
to heart attacks, aggravated asthma, migraine
headaches, insomnia, rheumatism, arthritis,
hay fever, and most allergies.
The effect of negative ions on sweat bathing
was discovered when researchers were trying
to account for the tremendous popularity
of sauna wood burning stoves over electric
stoves. Subjective reasons, such as the fragrance
of burned wood, did not fully explain why
Finns felt so refreshed after time in a wood
heated sauna and quite dulled, from certain
electrically heated saunas. Tests showed
that the practice of splashing water on super-heated
rocks produced an abundance of negative ions.
Many electric stoves, it turned out, were
not getting the rocks hot enough and the
glowing metal heating coils were spurting
more positive ions in the air. Researchers
learned that if the rocks were properly heated
in electric stoves, the positive ions, being
larger and less mobile, would ground out
on the hot stones. The buying habits of the
Finns, perhaps the most sophisticated of
sweat bathers, has forced many Finnish electric
stove companies to pay particular attention
to their sauna stove design. Researchers
also cited poor ventilation in modern saunas
as a cause of positive ion buildup; but,
for a discussion of the proper climatic conditions
for a sauna please refer to the appendix
material on construction and use. A more
detailed study regarding ions and saunas
can be found in Sauna Studies, published
by the Sauna Society of Finland, 1977.
Although tests have not been conducted
on other sweat baths, it is likely similar
negative ion production occurs in any sweat
bath that converts water to vapor quickly.
The Native American Indian sweat lodge comes
to mind.
Excerpted from Sweat, by Mikkel Aaland
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