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WINTER SWIMMING
- HEALTH OR HAZARD?
Hanna Krauss
Katedra Fizjologii Uniwersytetu Medycznego im. K. Marcinkowskiego w Poznaniu
THE MOST IMPORTANT PARAMETERS OF THE
INTERNAL ENVIRONMENT OF THE BODY:
BODY TEMPERATURE
pH of blood and body fluids
osmotic pressure
volume of the body fluids
the concentration of chemicals in body fluids
arterial blood pressure
partial pressure of oxygen and carbon dioxide in the blood
The control over these parameters is via receptors (mainly
chemoreceptors) that transmit the information about the specified
parameter values to the connection points where the comparison is made
between​detected value and the constant correct value (set point) or, more
commonly, with its acceptable ranges. If the current parameter is too high
or too low, the centre of the integrating forces effectors to give a response
appropriate to the situation.
THERMOREGULATION
Thanks to the physiological mechanism the human body temperature
is fixed at 37°C ± 0,5 - 0,7°C.
BODY TEMPERATURE
Is it possible to
survive?
Heatstroke
Brain damage
Thermal control
seriously
threatened
Heat therapy
Intensive exercising
Normal
Thermal control
efficient during
febrile diseases,
working, health
Thermal control
threatened
No thermal
control
MECHANISMS TO MAINTAIN THERMAL
HOMEOSTASIS
THERMOREGULATION ELEMENTS:
THERMODETECTORS
THERMORECEPTORS
THERMOREGULATION CENTER
CHEMICAL THERMOREGULATORY
EFFECTORS
PHYSICAL THERMOREGULATORY
EFFECTORS
THERMOREGULATORY CENTRE
 is located in the hypothalamus
the front part is the centre
that’s responsible for the
elimination of the warmth and
regulation of its loss
in the rear there’s a heat preservation centre,
which is responsible for the retention of the heat
in the body and stimulating its production
MECHANISMS ACTIVATED AT LOW
TEMPERATURES:
 GENERATING THE HEAT
 CHILLS
  INCREASED METABOLISM
  INCREASED PHYSICAL ACTIVITY

 INCREASE IN THE ACTIVITY OF THE
ENDOCRINE SYSTEM
(T3, T4, CATECHOLAMINES, GLUCAGON)
 HEAT LOSS
 CUTANEOUS VASOCONSTRICTION
 RELOCATION OF THE BLOOD INTO INTERNAL
ORGANS
 GOOSEBUMPS
 SLOWING OF THE BLOOD CIRCULATION
WHERE DOES THE HEAT COME FROM?
 muscles work
 shivering
 intensification of
metabolic processes in
tissues
(input of adrenaline,
noradrenaline, thyroid
hormones)
WHERE DOES THE HEAT COME FROM?
 When body is subjected to low temperatures, skeletal
muscles tremor, and increased tonicity becomes a source
of heat.
 Muscle tremor is directly related to the breakdown of ATP
(adenosine triphosphate) to ADP (adenosine
diphosphate) and inorganic phosphate.
 ADP accelerates the oxidation of substrates in the
mitochondria. This is accompanied by energy loss in the
form of heat.
 The main source of energy for shrinking muscles are
carbohydrates and lipids.
Effects of hypothermia on the body
TYPES OF HYPOTHERMIA:
PRIMARY - there is a decrease in body temperature due to the
impact of physical factors such as when the body is in cold water
during the cold snowy blizzard, with no warm or waterproof
clothing.
SECONDARY -caused by cardiovascular and vasodilators agents
lowering blood pressure, febrifuges, neuroleptic medications and
drugs. Medications can alter body temperature in a specific way:
-by acting on the thermoregulatory centres or non-specifically
- acting on other nerve centres or neural pathways
t
3 STAGES OF HYPOTHERMIA
(according to clinical criteria)
MILD 32-35°C
MODERATE 28-35°C
-amnesia,
-apathy,
-mental confusion,peripheral
vasoconstriction,
-increased heart rate,chills
-EEG disturbances,
-hallucinations,
-loss of consciousnessdecrease in heart rate and
cardiac output,
-cardiac arrhythmias,
-prolonged heart
contraction,-partial
reflexes,
-stiffness,
-no chills
SEVERE <28°C
-coma,
-decreased brain
electrical activity,-ABPdrop,
-decrease in heart rate,
-bradycardia,
-no radial pulse,ventricular fibrillation or
asystole,-apnoea,
-lack of reflexes
PHYSIOLOGICAL ZERO
 The limit of temperature for the tissue, below which
physiological functions while retaining the ability of tissue to
return to normal.
 31C is the highest value of the physiological zero for the
cerebral cortex, 27C-28C for the brain stem and 24C for
the spinal cord.
WHEN CAN IT OCCUR?
 Hypothermia is often accompanied by illnesses such as diabetic
coma, hypoglycemia, hypothyroidism, massive bleeding or
severe burns.
 Lowering of the body temperature can be observed in the
following states such as anorexia nervosa and obesity.
 Slowly progressing lowering of the body temperature, even at
room temperature, can be observed in the elderly,
malnourished, with injuries to the central nervous system,
autonomic or motor dysfunction of the nervous system.
 Hypothermia in the course of some infectious diseases
(cholera, diphtheria, smallpox) is the result of toxic damage of
organs involved in thermoregulation.
BODY'S REACTION TO COLD
 When running cold, the body launches a number of
adaptive responses. They occur when the internal
temperature of the body drops below 36.5°C.
Generally they can be divided into behavioral and
autonomic.
 Organ and metabolic responses are the result of:




exposure time and intensity with which cold works on the body,
neural and humoral response to stress,
speed of depletion of energy reserves,
remaining conscious.
THE RESPONSE TO LOW
TEMPERATURES
-To temporary setback of the temperature
our body reacts with goosebumps - vestigal
ruffled hair mechanism - so called pilomotor
reflex.
-At the same time the cutaneous blood flow
through blood vessels is reduced - so that
the body loses less heat.
-Shivering - muscle contractions are known
for releasing large amounts of heat.
-Longer presence in low temperatures,
causes body’s metabolic rate to rise, i.a. due
to increasing the levels of thyroid hormones.
HYPOTHERMIA <35°C
ANIMATION PHASE
34°C-32°C
CENTRES REDUCED
ACTIVITY PHASE
32°C-27°C
HEBETUDE
PHASE
<27°C-26
ADAPTIVE MECHANISMS
- animation phase
 Stimulation of peripheral thermoreceptors starts stress response.
The result is a stimulation of the adrenergic system, as well as
secretion of the hormones of the adrenal medulla.
Catecholamines stimulate the respiratory center and
cardiovascular center in the medulla. Intensified work of heart and
respiratory system is accompanied by increased heat production.
At the same time, thermoregulatory center stimulates the α motor
neurons, what leads to an increase in skeletal muscle tonicity,
which, in turn, increases heat production by about 50%.
 If the amount of heat supplied in this way is insufficient - shivering
thermogenesis is activated. ATP hydrolysis releases heat, and cell
respiratory chain reactions running at the same time produce
additional quantities. The result is an increase in metabolism and
heat production by up to 500%.
ADAPTIVE MECHANISMS
 As the cooling of the body advances, there’s secretion of
both TSH and thyroid hormones, resulting in an increased
metabolism (non-shivering thermogenesis) and heat
production.
 Increase in heat production is accompanied by reduction
of its loss, which occurs by constriction of the blood
vessels of the skin and subcutaneous tissue
(centralization of the blood flow) and the abolition of sweat
gland activity.
 During this phase a characteristic blood flow, through the
blood vessels of peripheral parts of the body occurs - the
so-called Lewis reaction.
 If cooling is of significant degree, then periodic dilation
appears and the blood flow increases. This mechanism is
designed to protect the body against frostbite.
 If the temperature of these areas is further reduced, blood
flow ceases completely vulnerable areas.
REDUCED ACTIVITY OF THE CENTRES
OF THE MEDULLA OBLONGATA
 When the body temperature drops below 34°C, there
occurs progressive cardiac release - the impact of
cold blood stimulus-conducting system of the heart.
 At temperatures below 28°C blocks appear in the
heart; in the case of anesthesia and surgical
ventricular fibrillation can occur.
 Coronary blood-flow during deep hypothermia is
significantly reduced (to 40% of baseline), but
proportionally greater than in other tissues and
organs where it reaches values ​lower than 20% of
the rate at the start.
 This is due to redistribution of the blood and selfregulation of coronary blood flow, the effect is
proportional to the oxygen consumption by the heart.
LESION
 Cold inhibits the activity of the respiratory center.
 Both the dead anatomical and physiological space increases as well as
residual blood in the lungs.
 Typical of hypothermia is to increase the affinity of hemoglobin with
oxygen (dissociation curve shifts to the left).
 In kidneys, proportionally to the decrease in temperature the feedback resorption in
renal tubules reduces. It is particularly important to reduce the resorption of sodium
ions. Increased loss of sodium ions, although filtration is reduced, causes the
amount of urine to increase - at a temperature of 32°C twice or even three times at
30°C.
 Loss of the body water is the cause of increasing blood viscosity.
 There is reduction in K + ions concentration as a result of their displacement to the
intracellular space. However, increase in the concentration of potassium in the
extracellular fluid, reflects a deep acidosis, cell lysis, and the withering away of
tissue.
 Acidosis is growing due to increased CO2 retention, caused by impaired
microcirculation. Due to increased viscosity of the blood increases blood pressure.
Only lowering the temperature of the organism below 32°C causes a decrease in
blood pressure, mainly due to worsening heart failure. At a temperature of 25℃ left
ventricular systolic pressure is reduced by more than 50%.
LESION
 Lowering the body temperature is accompanied by decrease in
cerebral blood flow by 6-7% for each 1°C.
 At the same time excitability of the cortical centres disappears.
In humans, even at body temperature of 35°C, life-threatening
psychiatric symptoms consisting mainly of a lack of willingness
to fight for survival, confusion, inability to articulate speech can
be observed.
 At 30°C, there is a loss of consciousness and inability to
perform voluntary movements.
 The gastrointestinal tract reduces peristalsis. At lower
temperatures up to 34°C, ileus can occur.
 Blood flow in the liver is reduced, although this decrease is
smaller than in other organs; stagnation of blood increases and
the fluids move into the extracellular space. Detoxifying abilities
of the liver are reduced, the secretion of bile is decreasing.
Pancreas’ exocrine function is inhibited.
HEBETUDE
letarg
 Symptoms similar to the symptoms of clinical death develop,
i.e. cooling of the body and pale skin, no pulse at the periphery,
no neurological reflexes and muscle stiffness. Cardiovascular
activity and respiration is almost inconceivable.
 In deep stage of hypothermia reduction of neurosecretion
within the hypothalamic-pituitary axis can be observed, and
reduced secretion of thyroid hormones. The secretion of
catecholamines is reduced, which at temperatures below 20°C
stops completely, peripheral effects of adrenaline are also
abolished. In this phase, thermoregulation activities are still
preserved which is reflected in shivering and increased oxygen
consumption during the heating of the system. If effects of cold
on the system are long-termed-changes are similar then, but
after a few hours death occurs, as a result of exhaustion of
energy reserves of the system.
BRAIN FUNCTIONS IN HYPOTHERMIA
 32oC – first changes in EEG
 31oC –inhibiting activity of
the cerebral cortex
 loss of consciousness
 < 25oC – loss of brain and
spinal reflexes
 20o-18oC – electric silence in
EEG
ACCLIMATIZATION TO COLD
The increase in
thermal insulation
properties of the
coatings
development of subcutaneous
adipose tissue
ntensity of metabolic
processes
The role of the
brown adipose
tissue
WINTER SWIMMING
Clubs of walruses around the
world
Ideas of winter
swimming:> health
>energy
>extreme sport
THE EFFECTS OF SWIMMING IN
COLD WATER
psychological
metabolic
endocrinal
cardiovascular
HAZARD
or
HEALTH
>Usually the walruses immerse themselves in water for a very short time - about 10-20
seconds, though there are some who do it up to a few minutes, even though it’s not too
safe.>Some plunge their heads, but most people enter only deep enough for the water
to reach their neck. The icy water stimulates the whole body, starting with the skin
receptors.
>Danger signals activate the nervous, endocrinal and immune system etc.
The production of heat dramatically rises, followed by dermic vasoconstriction which
prevents heat loss.The body warms up, the internal temperature rises, the skin cools.
HAZARD?
Source/Quelle: Massachusettsmike
H
A
Z
A
R
D
?
In the United Kingdom, each year, from 400 to 1,000 people die from
hypothermia during swimming in cold water
(including fatal accidents, ships and boats).
The causes of death are usually myocardial infarction and heart failure,
abnormal blood flow in the brain and heart rhythm disturbances, caused
by the autonomic nervous system.
Tipton M., Eglin C., Gennser M., Golden F. Lancet 1999, 354, 626-629
HAZARD?
>Concentration of stress hormones in the blood increases rapidly,
in order to stimulate the production of heat by generating the
chills. Chills begin very quickly to generate more heat through
muscle work.
This leads to increased muscle tension, chills and muscle fatigue
in less experienced swimmers, resulting in a dramatic
deterioration of swimming skills.
>If panic adds up, we can expect higher risk of drowning. If the
person does not drown, then the low temperature will lead to
hypothermia, which may also lead to death.
Tipton M., Eglin C., Gennser M., Golden F. Lancet 1999, 354, 626-629
HAZARD?
RESPONSE TO COLD WATER:
-Uncontrolled, very quick and rapid breathing, followed
by hyperventilation.
-Heart attack, which can occur when the temperature of
the blood returning to the heart is suddenly reduced.
This can cause atrial fibrillation.-Drowning and cardiac
arrest are the most common causes of demise, although
it is the low temperature and hypothermia that are
commonly believed to be responsible for the death.
Kolettis TM et al. Medical Hypotheses, 2003, 61, 654-656
HEALTH?
Bathing in an air-hole
causes change in
walruses psyche.
The increase in the secretion
of endorphins
-mild euphoria,
-tide of vitality
-peace of mind
HEALTH?
Human body has a very high
potential to adapt to operating in
difficult environments. Taking a
cold shower (10 degrees
Centigrade) for about 3 minutes
reduces the stress caused by the
cold by about 20-30%.
REGULAR EXPOSURE TO COLD
Stimulation of tolerance to low temperatures:
thermogenesis:
-non-shivering
-shivering
circulatory
system
WALRUSES THERMOGENESIS
The mechanism of non-shivering thermogenesis:
-β-adrenergic receptors more
sensitive to catecholamines
-adrenergic stimulation of muscle
tissue and / or fat
Simeckova M. et al. J. Therm Biol 2000, 25, 437-442
Simonsen L. et al. Int.J.Obes.Relat.Metabol.Disord.1993, 17 (suppl.3), S47-S51
POSITIVE EFFECTS OF REGULAR
WINTER SWIMMING
-Improved insulin tolerance in
patients with type II diabetes
-Reduction of endothelial
dysfunction vascular
-Inhibition of atherosclerosis
Hermanussen M et al. Archic Med. Res 1995, 54, 45-51
Dugue B et al. Clin Physiol 2000, 20, 114-121
POSITIVE EFFECTS OF REGULAR
WINTER SWIMMING
-The increase in white blood
cells, IL-6
-Strengthen the immune
response
-Reduction (by 40%) in the
number of cases of respiratory
diseases
Arcaro G et al. Circulation, 2002, 105, 576-582
Brenke R Therapeutikon 1990, 4,466-472
POSITIVE EFFECTS OF REGULAR
WINTER SWIMMING
Improved antioxidant protection:
-increase in the activity of
antioxidant enzymes-increase in
plasmas antioxidant capacityshielding tissues from damage
caused by free radicals
Siems W G et al. QJMed 1999, 92, 193-198
Siems W G et al. Free Rad Biol Med. 1994, 16, 299-305
Kloner R A et al. Circulation 2001, 104, 2981-2989