ADAPTATIONS TO HIGH ALTITUDE

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ADAPTATIONS TO HIGH ALTITUDE
2

• VENTILATION
• BICARBONATE IONS
• 2,3-DIPHOSPHOGLYCERATE (2,3-DPG)
• RED BLOOD CELL (RBC) AND HEMOGLOBIN (Hb)
  CONCENTRATION
• CAPILLARIZATION AND CELLULAR ADAPTATIONS
• SUBMAXIMAL AND MAXIMAL EXERCISE RESPONSES
• BODY FLUIDS
• BODY COMPOSITION
• METABOLISM
• NEUROHORMONAL ADAPTATIONS
• PERCEPTUAL AND PSYCHOMOTOR FUNCTIONS
• ALTITUDE TRAINING AND COMPETITION
• GENDER DFFERENES

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• ABBREVIATIONS
• VE EXPIRED VENTILATION RATE
• VO2 OXYGEN UPTAKE RATE
• VO2MAX MAXIMAL OXYGEN UPTAKE RATE
• Q CARDIAC OUTPUT
• SV STROKE VOLUME
• HR HEART RATE
• Hb HEMOGLOBIN
• RBC RED BLOOD CELLS
• OCC OR O.C.C OXYGEN CARRYING CAPACITY OF BLOOD
• A - V O2 DIFF ARTERIAL - VENOUS OXYGEN
  DIFFERENCE (I.E., OXYGEN EXTRACTION)
• O2 OXYGEN
• CO2 CARBON DIOXIDE
• PO2 PARTIAL PRESSURE OF OXYGEN
• PCO2 PARTIAL PRESSURE OF CARBON DIOXIDE
• H HYDROGEN IONS
• PIO2 PARTIAL PRESSURE OF INSPIRED OXYGEN
• PICO2 PARTIAL PRESSURE OF INSPIRED CARBON
  DIOXIDE

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RESTING VENTILATION (VE)

• VE INCREASES WITHIN A FEW HOURS AFTER ARRIVING
  AT HIGH ALTITUDE (FIG 13-1)
• THE INCREASED VE WILL
• - INCREASE PAO2 AND HENCE SaO2
• - DECREASE PACO2 AND PaCO2
• - INCREASE pH

5

• THUS, AFTER ACCLIMATION FOR A GIVEN PI02, PAO2 IS
  HIGHER AND PACO2 IS LOWER
• (FIG 13-2)

6

• ALSO, NATIVE HIGHLANDERS HAVE AN INCREASED
  PULMONARY DIFFUSION CAPACITY (PDC) DUE TO
  FUNCTIONAL AND STRUCTURAL CHANGES (E.G., HIGHER
  PULMONARY CAPILLARY BLOOD FLOW AND SMALLER DEAD
  SPACE) THAT TEND TO OCCUR PRIMARILY DURING THE
  DEVELOPMENTAL YEARS
• NON-NATIVE HIGHLANDERS (ACCLIMATED LOWLANDERS)
  SHOW NO CHANGE IN PDC DURING REST OR EXERCISE

7

• THE INCREASE IN RESTING VE IS DUE TO MECHANISMS
  RELATED TO HYPOXIA AND HYPOXIC INDUCED
  HYPERCAPNIA AND REDUCED BLOOD pH
• BOTH CENTRAL (MEDULLA OBLONGATA) AND PERIPHERAL
  (CAROTID BODIES AND AORTIC ARCH) CHEMORECEPTORS
  ARE INVOLVED IN THE VENTILATORY ADAPTATION
• IN ADDITION, HYPOXIA (DECREASED CaO2) INCREASES
  BRAIN TISSUE LACTATE PRODUCTION RESULTING IN
  ACIDOTIC CEREBRAL INTERSTITIAL FLUID, WHICH
  STIMULATES MEDULLARY CHEMORECEPTORS

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• DETERMINANTS OF VENTILATORY RESPONSE
• GENETICS
• MAGNITUDE OR SEVERITY OF HYPOXIA
• YEARS OF ALTITUDE EXPOSURE
• AGE AT ARRIVAL TO ALTITUDE (FIG 13-3 VE OF
  NON-NATIVE HIGHLANDERS ARE INTERMEDIATE TO
  LOWLANDERS AND NATIVE HIGHLANDERS)
• PHYSICAL ACTIVITY OR EXERCISE PATTERNS

9

• VENTILATORY ADAPTATION PROGRESSES THROUGH AN
  INTERMEDIATE HYPERVENTILATORY PHASE TO A PHASE
  WHERE HYPOXIC SENSITIVITY IS DECREASED THIS
  REPRESENTS A HABITUATION RESPONSE
• NATIVE HIGHLANDERS HAVE LOWER VENTILATION THAN
  LOWLANDERS OR NON-NATIVE HIGHLANDERS

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• INCREASE IN THE SEVERITY OF HIGH ALTITUDE
  EXPOSURE AND/OR YEARS OF ALTITUDE EXPOSURE, AS IN
  NATIVE HIGHLANDERS, WILL
• 1. INCREASE PaCO2 SET POINT OR THRESHOLD FOR
  THE ONSET OF VE
• 2. LOWER PaO2 SET POINT OR THRESHOLD FOR THE
  ONSET OF VE

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EXERCISE VENTILATION RATE

• DURING SUBMAXIMAL EXERCISE, AN ACUTE RESPONSE TO
  HIGH ALTITUDE IS AN ELEVATED VENTILATORY RATE
  OVER AND ABOVE NORMOXIC CONDITIONS

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• INITIAL STAGES OF ADAPTATION TO HIGH ALTITUDE
  FURTHER INCREASES THE VE DURING EXERCISE
• (FIG 13-4)

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• AS INDICATED IN FIGURE 13-5, BOTH NATIVE
  HIGHLANDERS AND NON-NATIVE HIGHLANDERS
  (ACCLIMATED LOWLANDERS) SHOW A SIMILAR
  HYPER-VENTILATORY RESPONSE TO ALTITUDE DURING
  EXERCISE

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BICARBONATE IONS

• DURING THE FIRST FEW DAYS AT HIGH ALTITUDE, THE
  INCREASE VE REDUCES THE HYDROGEN CONCENTRATION IN
  THE BLOOD AND HENCE, THE pH OF THE BLOOD
  INCREASES THE INCREASE IN pH SHIFTS THE Hb-O2
  DISSOCIATION CURVE TO THE LEFT INCREASING THE
  AFFINITY OF Hb FOR O2 AND HENCE, REDUCING THE
  BOHR EFFECT OR RELEASE OF OXYGEN TO MUSCLE TISSUE
• HOWEVER, WITHIN SEVERAL DAYS THE pH OF THE BLOOD
  IS STABILIZED NEAR NORMAL LEVELS DUE TO AN
  INCREASE IN THE ELIMINATION OF BICARBONATE IONS
  IN THE URINE THE KIDNEYS INCREASE BICARBONATE
  ION EXCRETION TO NORMALIZE pH

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ALTITUDE INCREASES CARBON DIOXIDE AND LACTATE
PRODUCTION
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2,3-DIPHOSPHOGLYCERATE(2,3-DPG)
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• THE INCREASED VE DURING THE FIRST FEW DAYS OF
  HIGH ALTITUDE EXPOSURE ALSO STIMULATES RBC
  GLYCOLYSIS AND ALONG WITH THE DECREASE IN PO2
  WHICH STIMULATES DPG MUTASE, 2,3-DPG LEVELS
  INCREASE

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• THE INCREASE IN
• 2,3-DPG LEVELS SHIFTS THE Hb-02 DISSOCIATION
  CURVE TO THE RIGHT
• THE SHIFT OF THE CURVE TO THE RIGHT DOES NOT
  AFFECT 02 LOADING IN THE LUNGS, BUT INCREASES O2
  AVAILABILITY (UNLOADING) TO THE MUSCLE TISSUE BY
  26-FOLD

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THIS MAJOR ADAPTATION OCCURS WITHIN 48 HOURS OF
HIGH ALTITUDE EXPOSURE
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• NOTE EXERCISE DECREASES pH AND INCREASES
  TEMPERATURE AND PC02 THEREBY SHIFTING THE CURVE
  TO THE RIGHT, WHICH INCREASES OXYGEN
• AVAILABILITY TO THE MUSCLE TISSUE

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PHYSICAL WORK CAPACITY (PWC) AT ALTITUDE
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• PHYSICAL WORK CAPACITY (PWC) IS INCREASED WITHIN
  2-3 WEEKS OF HIGH ALTITUDE EXPOSURE
• REASONS FOR THE INCREASE IN PWC
• 1. INCREASED RBC AND Hb CONCENTRATIONS
• - INCREASED OXYGEN CARRYING CAPACITY OF THE
  BLOOD
• - INCREASED SaO2

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• NOTE HYPOXEMIA (LOW PO2 IN THE BLOOD)
  STIMULATES THE RELEASE OF ERYTHROPOIETIN FROM THE
  KIDNEYS THAT INCREASES RBC PRODUCTION IN THE RED
  BONE MARROW
• NOTE LONG-TERM RESIDENTS AT 3,100 M SHOW AN
  INCREASE IN BLOOD VOLUME DUE TO BOTH AN INCREASE
  IN PLASMA VOLUME AND RBC LEVEL WITH NO CHANGE IN
  HEMATOCRIT SINCE VASCULAR ANATOMY PROVIDES THE
  UPPER LIMIT FOR ANY INCREASE IN TOTAL BLOOD
  VOLUME, RESIDENTS AT 4,300 M SHOW AN INCREASE IN
  BLOOD VOLUME AND RBC LEVEL, BUT A DECREASE IN
  PLASMA VOLUME RESULTING IN AN INCREASE IN
  HEMATOCRIT AND BLOOD VISCOSITY

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• REASONS FOR INCREASD PWC (CONTINUED)
• 2. INCREASED CONTRIBUTION OF FAT METABOLISM
  TO ENERGY PRODUCTION
• RESULTING IN GLYCOGEN SPARING AND LOWER
  LACTATE LEVELS FOR A GIVEN WORKLOAD
• 3. DECREASE IN RELATIVE SUBMAXIMAL EXERCISE
  INTENSITY DUE TO THE
• INCREASE IN MAXIMAL OXYGEN UPTAKE RATE
  (VO2MAX)???
• - NO CHANGE IN SUBMAXIMAL OXYGEN UPTAKE RATE
  (VO2)
• - INCREASE IN VO2MAX

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EFFECTS OF HIGH ALTITUDE ON MAXIMAL OXYGEN UPTAKE
RATE (V02MAX)

• ALTITUDE INITIALLY DECREASES VO2MAX WHICH
  INCREASES THE RELATIVE EXERCISE INTENSITY OF AN
  ABSOLUTE SUBMAXIMAL WORKLOAD

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• WIDE INDIVIDUAL VARIABILITY EXISTS IN THE ACUTE
  DECREASE IN VO2MAX AT ALTITUDE

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EFFECTS OF HIGH ALTITUDE ON MAXIMAL OXYGEN UPTAKE
(V02MAX) (CONTINUED)

• 2. LONG-TERM EXPOSURE DOES NOT FURTHER DECREASE
  VO2MAX IF PHYSICAL ACTIVITY IS MAINTAINED
• 3. DETRAINING MAY BE ACCELERATED AT HIGH
  ALTITUDE DUE TO
• - DECREASE IN LEAN BODY WEIGHT (LBW)
• - DEVELOPMENT OF PULMONARY OR CEREBRAL
  EDEMA AT ELEVATIONS
• gt 12,500 FEET
• - MOUNTAIN SICKNESS (HEADACHE, NAUSEA,
  VOMITING, ANOREXIA,
• INDIGESTION, FLATUS, CONSTIPATION, AND SLEEP
  DISTURBANCES)

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4. ALTITUDE'S ABILITY TO DECREASE VO2MAX MAY OR
MAY BE NOT ALTERED BY SHORT-TERM ALTITUDE
ACCLIMATION OF 3-5 WEEKS
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NOTE THE TWO BEST STUDIES REPORT CONFLICTING
RESULTS (HORSTMAN REPORTED AN INCREASE WHEN
EXPRESSED IN ML/KG/MIN YOUNG REPORTED NO CHANGE
WHEN EXPRESSED IN L/MIN)
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• IF VO2MAX IS INCREASED, IT IS PROBABLY DUE TO A
  DECREASE IN BODY WEIGHT, PRIMARILY FROM A
  DECREASE IN FAT WEIGHT OR DIURESIS (DECREASE IN
  TOTAL BODY WATER) AS A DECREASE IN LEAN BODY
  WEIGHT WOULD DECREASE VO2MAX IF LEAN BODY WEIGHT
  IS DECREASED, APPARENTLY AN INCREASE RBC AND Hb
  LEVELS OFFSET THE POTENTIAL LOSS OF OXIDATIVE
  CAPABILITIES THAT MAY BE ASSOCIATED WITH THE
  DECREASE IN LBM

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SYSTEMATIC O2 TRANSPORT AND DELIVERYFICK
EQUATION VO2 Q X O2 EXTRACTION OR VO2 SV
X HR X A - V O2 DIFFERENCE

• ACUTE EXPOSURE
• DECREASE IN SaO2 AND CaO2 WILL STIMULATE SNS
  WHICH INCREASES HR AND HENCE Q AT A GIVEN
  SUBMAXIMAL WORKLOAD CONSEQUENTLY VO2 AT AN
  ABSOLUTE WORKLOAD IS MAINTAINED
• INCREASED CARDIAC OUTPUT (Q) DUE TO INCREASED HR
  TO MAINTAIN VO2 AT A GIVEN SUBMAXIMAL WORKLOAD

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HIGH ALTITUDE ADAPTATION

• RELATED TO
• CHANGES IN CARDIAC OUTPUT
• (SV X HR)
• CHANGES IN OXYGEN EXTRACTION (I.E., ARTERIAL -
  VENOUS OXYGEN DIFFERENCE)

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HIGH ALTITUDE ADPATATION

• DECREASED CARDIAC OUTPUT (FIG 13-8) DUE TO A
  DECREASE IN STROKE VOLUME
• DECREASE IN Q APPEARS AFTER 48 HOURS AND
  CONTINUES TO DECREASE FOR 8-9 DAYS

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• NATIVE HIGHLANDERS (NH) AND ACCLIMATED
  LOWLANDERS (AL) BOTH HAVE A SIMILARLY REDUCED Q

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• DECREASE IN CARDIAC OUTPUT IS DUE TO
• DECREASE IN RESTING, SUBMAXIMAL, AND MAXIMAL SV
• DURING FIRST TWO WEEKS OF ALTITUDE ADAPTATION,
  PLASMA VOLUME DECREASES BECAUSE OF THE INCREASE
  IN RBC LEVELS AND THE DECREASE IN PLASMA VOLUME,
  HEMATOCRIT AND BLOOD VISCOSITY INCREASES THIS
  WOULD POTENTIALLY DECREASE CARDIAC OUTPUT DUE TO
  AN INCREASE IN PERIPHERAL RESISTANCE (Q P/R)

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• REASONS FOR A DECREASE IN SV
• DECREASED CARDIAC FILLING (I.E., EDV), POSSIBLY
  DUE TO TACHYCARDIA, INCREASED VENTILATION RATE,
  DECREASED PLASMA VOLUME, AND/OR INCREASED BLOOD
  VISCOSITY THE INCREASED VISCOSITY AND DECREASED
  PLASMA VOLUME MAY DECREASE VENOUS RETURN OF BLOOD
  FLOW TO THE HEART
• INCREASED ESV DUE TO DECREASED MYOCARDIAL
  CONTRACTILITY (FRANK-STARLING LAW

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• NOTE NATIVE HIGHLANDERS (NH) AND ACCLIMATED
  LOWLANDERS (AL) BOTH
• HAVE A SIMILARLY REDUCED Q AS SHOWN PREVIOUSLY
  IN FIG 13-9
• - NATIVE HIGHLANDERS HAVE GREATER
  SV AND LOWER HR THAN THE ACCLIMATED LOWLANDERS
• - ACCLIMATED LOWLANDERS HAVE A HIGHER HR AND
  LOWER SV THAN THE NATIVE HIGHLANDERS

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• ARTERIAL - VENOUS OXYGEN DIFFERENCE (I.E., OXYGEN
  EXTRACTION)
• MAXIMAL EXERCISE A -V O2 DIFFERENCE IS THE SAME
  OR SLIGHTLY GREATER IF TISSUE ADAPTATIONS HAVE
  OCCURRED

40

• TISSUE ADAPTATIONS OF LONG-TERM RESIDENTS AT HIGH
  ALTITUDE, WHICH WOULD INCREASE SUBMAXIMAL AND
  MAXIMAL OXYGEN EXTRACTION CAPABILITIES, INCLUDE
• INCREASED CAPILLARIZATION
• INCREASED MYOGLOBIN CONCENTRATION
• INCREASED MITOCHONDRIAL DENSITY
• INCREASED OXIDATIVE ENZYME LEVELS

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• THEREFORE, IF VO2MAX CONTINUES TO BE REDUCED
  AFTER ADAPTATION TO ALTITUDE, IT IS PROBABLY DUE
  TO A DECREASE IN Q THAT IS GREATER THAN THE
  INCREASE IN OXYGEN EXTRACTION

42

• A - V O2 DIFF IS INCREASED DURING SUBMAXIMAL
  EXERCISE AT THE SAME ABSOLUTE WORKLOAD THEREBY
  OFFSETTING THE SUBMAXIMAL EXERCISE DECREASE IN Q
  HENCE, SUBMAXIMAL VO2 WHEN PERFORMING THE SAME
  ABSOLUTE SUBMAXIMAL WORKLOAD IS UNCHANGED

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• REASONS FOR THE INCREASE IN SUBMAXIMAL A - V 02
  DIFFERENCE
• INCREASE IN VE
• INCREASE IN 2,3-DPG LEVELS
• INCREASE IN RBC AND Hb LEVELS
• LONG-TERM TISSUE ADAPTATIONS

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BODY FLUIDS

• ADAPTATIONS TO HIGH ALTITUDE DURING THE FIRST TWO
  WEEKS INCLUDE
• NO CHANGE IN TOTAL BODY WATER
• DECREASE IN PLASMA VOLUME
• DECREASE IN EXTRACELLULAR AND INTERSTITIAL
  VOLUMES
• INCREASE IN INTRACELLULAR VOLUME
• INCREASE IN BLOOD HEMATOCRIT AND BLOOD VISCOSITY
  DUE TO THE DECREASE IN PLASMA VOLUME AND INCREASE
  IN RBC
• REVIEW FIG 13-11 AND TABLE 5-2

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• LONG-TERM ADAPTATION TO HIGH ALTITUDE
• LONG-TERM RESIDENTS AT 3,100 M SHOW AN INCREASE
  IN PLASMA VOLUME AND RBC LEVEL WITH NO CHANGE IN
  HEMATOCRIT
• SINCE VASCULAR ANATOMY PROVIDES THE UPPER LIMIT
  FOR ANY INCREASE IN TOTAL BLOOD VOLUME,
• LONG-TERM RESIDENTS AT 4,300 M SHOW AN INCREASE
  IN BLOOD VOLUME AND RBC LEVEL, BUT A DECREASE IN
  PLASMA VOLUME RESULTING IN AN INCREASE IN
  HEMATOCRIT AND BLOOD VISCOSITY THE INCREASE IN
  BLOOD VISCOSITY WILL DECREASE CARDIAC OUTPUT AS
  CARDIAC OUTPUT IS EQUAL TO THE PRESSURE GRADIENT
  (I.E., MEAN ARTERIAL BLOOD PRESSURE) DIVIDED BY
  THE RESISTANCE TO BLOOD FLOW

48
BODY COMPOSITION

• DECREASE IN BODY WEIGHT DUE TO A DECREASE IN BOTH
  LEAN BODY WEIGHT AND FAT WEIGHT WEIGHT LOSS
  APPEARS TO BE INVERSELY RELATED TO FAT WEIGHT AS
  LEANER SUBJECTS SHOW A GREATER WEIGHT LOSS THAN
  HEAVIER, MORE FAT SUBJECTS
• DECREASE IN LEAN BODY WEIGHT (LBW)
• DECREASE POTENTIALLY IN FAT WEIGHT (FW)
• INCREASE IN PERCENT BODY FAT AS THE DECREASE IN
  LEAN BODY WEIGHT TENDS TO BE GREATER THAN THE
  DECREASE IN FAT WEIGHT

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• THE DECREASE IN BODY WEIGHT, LEAN BODY WEIGHT,
  AND FAT WEIGHT ARE DUE INPART TO A DECREASE IN
  CALORIC INTAKE AS APPETITE TENDS TO BE SUPPRESSED
  DURING THE INITIAL STAGES OF ALTITUDE ACCLIMATION

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METABOLISM

• INCREASED RESTING PLASMA FFA CONCENTRATION AFTER
  14-18 DAYS AT
• 4,300 METERS INDICATES INCREASED FAT METABOLISM
• INCREASED FFA METABOLISM TENDS TO INCREASE PWC
  AND ENDURANCE TIME TO EXHAUSTION DUE TO GLYCOGEN
  SPARING AS EVIDENCED BY
• - DECREASED BLOOD LACTATE
• - BETTER MAINTENANCE OF MUSCLE GLYCOGEN
  LEVELS
• REVIEW FIGURE 13-12

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• MECHANISMS FOR DECREASED MUSCLE GLYCOGENOLYSIS
  AND INCREASED LIPOLYSIS
• LOW CHO AND/OR HYPOCALORIC DIET INCREASES FAT
  METABOLISM
• SNS STIMULATION INCREASES CIRCULATING
  NOREPRINEPHRINE (NEPI) LEVELS THEREBY INCREASING
  FAT MOBILIZATION AND LIPOLYSIS

54

• THE BREAKDOWN OF CARBOHYDRATES SLOWS DOWN DUE
  TO DECREASED PFK ENZYME ACTIVITY
  (PHOSPHOFRUCTOKINASE IS THE RATE LIMITING ENZYME
  OF GLYCOLYSIS) PYRUVATE THAT IS FORMED FROM
  GLYCOGENOLYSIS IS CONVERTED INTO ACETYL CoA AND
  ENTERS THE KREBS CYCLE RATHER THAN INTO LACTIC
  ACID
• DECREASED BLOOD LACTIC LEVELS WHICH INCREASES FAT
  MOBILIZATION, AS INCREASED BLOOD LACTATE LEVELS
  INHIBITS FAT MOBILIZATION

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NEUROHORMONAL RESPONSES

• INCREASED SYMPATHETIC NERVOUS SYSTEM (SNS)
  STIMULATION AND HENCE CIRCULATING NOREPINEPHRINE
  (NEPI) LEVELS WITHIN 3-5 DAYS WHICH TEND TO
  PLATEAU AFTER ONE WEEK SNS ACTIVITY TENDS TO
  DIMINISH AFTER 1 MONTH DUE TO A DECREASE IN
  RECEPTORS AT THE BETA ADRENERGIC SITES INCREASED
  NOREPINEPHRINE LEVELS WILL
• A. INCREASE EXPIRED VENTILATION RATE
• B. INCREASE LIPOLYSIS
• C. INCREASE HEART RATE
• REVIEW FIGURE 13-13

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• ADAPTATION HAS NO EFFECT ON PARASYMPATHERIC
  NERVOUS SYSTEM (PNS) ACTIVITY
• TRANSIENT INCREASE IN THYROXIN DURING FIRST FEW
  DAYS WHICH MAY INCREASE BASAL VO2 AND WEIGHT LOSS
• LONG-TERM RESIDENTS HAVE HIGHER PLASMA INSULIN
  LEVELS AND/OR
• INCREASED INSULIN SENSITIVITY AS THEY HAVE
  FASTER GLUCOSE CLEARANCE AND HENCE, BETTER
  GLUCOSE TOLERANCE

58

• INCREASED CIRCULATING CORTISOL LEVELS DURING THE
  FIRST WEEK OF HIGH ALTITUDE WHICH EVENTUALLY
  RETURN BACK TOWARD BASELINE
• A. THE INCREASED CORTISOL LEVELS WILL HAVE A
  CATABOLIC EFFECT ON TISSUES TO PROVIDE AMINO
  ACIDS FOR GLUCONEOGENESIS, WHICH MAY CONTRIBUTE
  TO THE DECREASE IN LEAN BODY WEIGHT
• B. ALSO IN CONJUNCTION WITH NOREPINEPHRINE,
  CORTISOL STIMULATES LIPOLYSIS

59

• LONG-TERM RESIDENTS HAVE HIGHER PLASMA GROWTH
  HORMONE (GH) LEVELS DURING EXERCISE DUE TO A
  HIGHER SET POINT FOR GROWTH HORMONE LEVELS IN THE
  HYPOTHALAMUS AND HENCE, DECREASED HEPATIC
  CLEARANCE THE HIGHER CIRCULATING GROWTH HORMONE
  LEVELS
• A. MAY HAVE AN ANABOLIC EFFECT THAT MAY OFFSET
  THE DECREASE IN LEAN BODY WEIGHT OBSERVED DURING
  THE EARLY STAGES OF ADAPTATION
• B. WILL STIMULATE FAT MOBILIZATION AND
  LIPOLYSIS THEREBY INCREASING AEROBIC METABOLISM
  AND REDUCING OXYGEN DEFICIT AND LACTATE
  ACCUMULATION

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• DECREASED CIRCULATING ALDOSTERONE LEVELS MAY
  CONTRIBUTE TO THE OBSERVED DECREASES IN PLASMA
  VOLUME DURING THE INITIAL STAGES OF ADAPTATION AS
  ALDOSTERONE INCREASES WATER RETENTION BY THE
  KIDNEYS

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PERCEPTUAL AND PSYCHOMOTOR FUNCTIONS

• AFFECTS OF ALTITUDE ACCLIMATION ON CNS FUNCTION
  IS UNCLEAR AND NEEDS MORE RESEARCH

62

• DURING SUBMAXIMAL EXERCISE (85 OF VO2MAX), LOCAL
  FACTORS DOMINANT THE RPE AT SEA LEVEL AND ACUTE
  HIGH ALTITUDE WHEREAS CENTRAL FACTORS DOMINANT
  RPE AT CHRONIC ALTITUDE AS LACTATE LEVELS TEND TO
  BE LOWER

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TRAINING AND COMPETITION AT HIGH ALTITUDE
64

• TRAINING AT HIGH ALTITUDE MAY BE DETRIMENTAL TO
  COMPETITION AT SEA LEVEL AS ABSOLUTE TRAINING
  INTENSITY IS LOWERED AS VO2MAX IS DECREASED
  MOTOR UNIT SPECIFICITY IS COMPRISED
• INTERVAL TRAINING IS NOT DETRIMENTALLY AFFECTED
  BY HIGH ALTITUDE AND MAY EVEN BE ENHANCED DURING
  THE EARLY STAGES OF ACCLIMATION INTERVAL TRAINING
  MAY ALSO HELP MAINTAIN MUSCLE POWER AND HELP
  OFFSET REDUCTIONS IN ENDURANCE PERFORMANCE

65

• FOR COMPETITION AT HIGH ALTITUDE, LOWLANDERS
  SHOULD ALLOW 3 WEEKS TO ADAPT
• ALTHOUGH ACCLIMATED LOWLANDERS (AL) MAY HAVE AN
  EDGE OVER UNACCLIMATED LOWLANDERS (UL) AT
  ALTITUDE COMPETITIONS, THIS APPEARS TO BE
  ELIMINATED AT SEA LEVEL COMPETITIONS AS
• A. AL AND UL EXPERIENCE SIMILAR INCREASES IN
  VO2MAX WHEN COMING DOWN TO SEA LEVEL
• B. AL HAVE MORE ERYTHROCYTES AND OXYGEN
  CARRYING CAPACITY (WHICH DECREASE WITHIN 10
  DAYS), UL HAVE HAVE A HIGHER CARDIAC OUTPUT

66

• HOWEVER, NATIVE HIGHLANDERS WHO HAVE
  EXPERIENCED LONG-TERM
• ADAPTATIONS SUCH AS INCREASED CAPILLARIZATION,
  INCREASED PLASMA VOLUME, AND SUBCELLUAR TISSUE
  CHANGES (E.G., INCREASED MYOGLOBIN, MITOCHODRIA,
  AND OXIDATIVE ENZYME LEVELS) MAY HAVE AN
  ADVANTAGE IN SEA LEVEL COMPETITIONS AS WELL AS
  COMPETITIONS AT HIGH ALTITUDE

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• LIVE HIGH (2,000-2,700 M/6,560-8,855 FT) -TRAIN
  LOW (lt 1,000 M/3,280 FT)!
• LIVING HIGH
• INCREASES RBC MASS AND
• HEMOGLOBIN CONCENTRATION
• TRAINING LOW
• TRAINING CAN BE AT SEA LEVEL TRAINING
  INTENSITY/VELOCITY THEREBY INDUCING PERIPHERAL
  AND NEUROMUSCULAR ADAPTATIONS

68

• LIVE HIGH (2,000-2,700 M/6,560-8,855 FT) -TRAIN
  LOW (lt 1,000 M/3,280 FT)!
• IMPROVES SEA LEVEL MAXIMAL OXYGEN UPTAKE RATE
  AND ENDURANCE PERFORMANCE
• BENEFITS MAY LAST UP TO 3-WEEKS, PERHAPS
  LONGER, WHEN RETURNING TO SEA LEVEL LIVING AND
  TRAINING

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ALTERNATIVE STRATEGIES TO LIVE HIGH, TRAIN LOW

• SIMULATES HIGH ALTITUDE WHEN LIVING AND TRAINING
  AT LOW ALTITUDE
• NORMOBARIC HYPOXIA VIA NITROGEN DILUTION
  (NITROGREN APARTMENTS)
• HYPOXIC SLEEPING UNITS/TENTS
• MAY NOT HAVE THE SAME EFFECTS AS A HYPOBARIC
  ENVIRONMENT
• SIMULTATES SEA LEVEL TRAINING WHEN LIVING AND
  TRAINING AT HIGH ALTITUDE
• OXYGEN SUPPLEMENTATION

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GENDER DIFFERENCES IN HIGH ALTITUDE ADAPTATIONS
71

• NO MAJOR GENDER DIFFERENCES EXIST IN THE
  ADAPTATIVE PROCESSES AT HIGH ALTITUDE
• HOWEVER WHEN RETURNING TO SEA LEVEL, MEN TEND TO
  RETAIN INCREASED RBC CONCENTRATIONS LONGER
  (ERYTHROPOIETIC RESPONSE) THAN WOMEN AS MEN'S RBC
  LEVELS RETURN TO NORMAL SEA LEVEL VALUES MORE
  SLOWLY EVEN THOUGH THEIR PLASMA VOLUME RETURNS TO
  NORMAL SEA LEVEL VALUES MORE RAPIDLY THAN WOMEN
• THEREFORE, CHANGES IN BLOOD VISCOSITY FOLLOW A
  SIMILAR TREND IN MEN AND WOMEN WHEN RETURNING TO
  SEA LEVEL FROM HIGH ALTITUDE

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QUESTIONS??