Exercise at Altitude
(where the air is rare)
Who performs better at a
bike race in San Francisco…
the athlete who trains at
altitude, or the athlete who
trains sea level?
Why?
How high is high? (Dude)
Moderate = <12,000 ft
 High = 12,000 to 18,000 ft
 Very High = >20,000 ft
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Stress of Altitude
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The 4 “H”s
Hypoxia
 Hypothermia
 Hypoglycemia
 Hypohydration
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Additionally
• Suppressed Immune System
• Suppressed Emotional State
Stress of Altitude (Hypoxia)
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O2 % at sea level = 21%
O2 % at 22,000 ft = 21%
So why do we not assimilate as much
O2 at altitude as at sea level?
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Decreased PO2 results in Hypoxia.
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What is PO2?
How does O2 diffuse into blood and tissues?
How does PO2 effect this?
Acclimatization
(adaptation to the new natural environment)
IMMEDIATE
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Respiratory
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Hyperventilation
Body Fluids become more base as a result of
reduction in CO2 w/hyperventilation
Cardiac
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Increased heart rate at rest and at submax
work = increased cardiac output
Stroke Volume remains the same or decreases
Max VO-2 remains the same
Acclimatization
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LONGER TERM (day to weeks)
Respiratory
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Hyperventilation
Excretion of base via kidneys and concomitant
reduction in alkaline reserve
Cardiac
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Increased Sub-max Heart Rate
Sub-max cardiac output falls
Stroke volume decreases (Startlings Law)
Max VO-2 Decreases (decreased max HR and
stroke volume)
Acclimatization
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Hematological
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Decreased plasma volume
Increased hematocrit (?)
Increased hemoglobin
Increased # of RBCs
Possible increase in capillary beds (?)
Increased 2,3 DPG
Increased mitochondrial density
Increased aerobic enzymes in muscle
Acclimatization

Catecholamine Response

Nor-epinephrine
• Regulates HR, BP, SV, Vasc Resistance and
substrate use.
• Increases for 7 days and then stabilizes.

Epinephrine shows little to no increase
Acclimatization
(Acid Base Balance)
Hyperventilation leads to a decrease
in carbon-dioxide thus increasing pH
of all body fluids. This blunts
respiratory control.
 Body begins to excrete base through
renal tubules to normalize pH
 This increases resp. sensitivity and
allows for greater hyperventilation.

Acclimatization
(Acid Base Balance)
This decrease in “base” creates a
loss of the absolute alkaline reserve
inhibiting the bodies acid buffering
ability.
 This is made up for by a decrease in
acid production as a result of
reduced CNS drive, a decrease in
intracellular ADP and a reduction in
epinephrine output.
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Acclimatization Schedule
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Rapid ascent 0 to 7,500 ft 2 weeks to
adjust.
then 1 week per 2,000 ft up to 15,000 ft.
Riiiiight!
Climb to camp altitude
Active acclimatization
Move to next camp
Repeat as necessary
Summit
Get outta Dodge
Altitude Related Illnesses

All are exacerbated by:
Speed of ascent
 Altitude
 Health of Individual
 General susceptibility of individual
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Altitude Related Illnesses

Slow Ascent Symptoms
Diminished exercise capacity
 Shortness of breath
 Elevated HR
 Cheyne-Stokes (irregular nighttime breathing)
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Altitude Related Illnesses
Rapid Ascent
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Acute Mountain Sickness (AMS)
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Most common alt disorder
Can appear within 2 hours of ascent
Headache
Insomnia
Irritability
Weakness
Vomiting
Tachycardia
Breathing problems
Altitude Related Illnesses
Rapid Ascent

High Altitude Pulmonary Edema
(HAPE)
12 to 96 hours of ascent
 Can be treated on site but reduction in
elevation is best

Altitude Related Illnesses
Rapid Ascent
High Altitude Cerebral Edema
(HACE)
 Results from vasodilatation,
increased capillary hydrostatic
pressure.
 Must descend to accurately diagnose
and treat.
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Altitude Related Illnesses
Rapid Ascent
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Chronic Mountain Sickness (CMS
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Can occur after months or years at
altitude.
• Polycythemia
• Genetically linked EPO response to stress.
Altitude Related Illnesses
Rapid Ascent

High Altitude Retinal Hemorrhage
(HARH)
All climbers experience over 21,000 ft
 Hemorrhage of the macula results in
vision loss.
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NOTE – Eye Surgery
Body Composition and
Nutrition
Muscle Atrophy and weight loss occur at
altitude.
Depressed appetite
Dehydration
Increase BMR
Increased energy output
EAT, DRINK AND BE MERRY.
Body Composition and
Nutrition

Hypohydration
Increased respirations = dehydration
 Low Relative Humidity at altitude
 Greater loss in fecal matter
 Less absorption in gut
 Inadequate fluid intake
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• Low desire
• Pain in the butt to obtain
Physical Performance at
Altitude
Max strength is unaffected
 Capacity for repeated contractions is
progressively impaired
 Endurance is initially decreased but
improves with acclimatization.
 Decrease motor skills
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Why are track and field records broken
at altitude?
Mental Performance at
Altitude (Dumb and Dumber)
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Decreased short term memory
• Where did I park my car?
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Mental Acuity
• Let’s see it’s “I” before “E” except after no
wait it’s…
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Judgment/Decision making
• What in the hell are you thinking?
Summary
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As we gain alt the PO2 drops resulting in
inadequate hemoglobin saturation and a
decrease in aerobic capabilities
Ability to perform high intensity short
duration (sprint) physical activity is not
affected.
Reduced PO2 results in physiologic
responses that improve altitude
tolerance.
Summary
Hyperventilation and increased
submax cardiac output via elevated
HR are the primary immediate
responses to altitude.
 Medical problems may emerge as a
result of travel to altitude.
 AMS, HAPE and HACE are the most
common conditions.
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Summary
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Acclimatization entails
Reestablishment of acid-base balance
 Increased synthesis of RBC and
hemoglobin
 Improved local circulation and cellular
metabolism
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Summary
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Rate of acclimatization depends on the
elevation. Major adjustments takes about
2 weeks but may require 4 to 6 weeks at
higher altitudes.
Acclimatization does not fully compensate
for the stress of altitude as a result
vo2max remains depressed.
Training at altitude provides no more
benefit to sea-level performance than
equivalent sea level training.