Ch 24 - Exercise at Medium & High Altitude

Question 1

What is the main physiological challenge does high altitude pose?

Answer 1

The direct problem of altitude on human physiology is the decrease of ambient PO2

Not the reduction of barometric pressure per se or and change in relative concentrations (%) of gases in inspired ambient air

Question 2

What is ambient air PO2?

Answer 2

20.93 or 21%

Question 3

Air density decreases when…

Answer 3

one ascends above sea level

Question 4

What is the barometric pressure to sea level?

Answer 4

Pb = 760 mm Hg

Question 5

T of F: PO2 of air decreases directly with the fall in barometric pressure

Answer 5

True: PO2 = 0.2093 x Pb

Question 6

Stress of Altitude at sea level vs mt. Everest

Answer 6

Ambient PO2 at seal level = 159 mm Hg
Mt. Everest PO2 = 50 mm Hg
This is 30% of the O2 available at sea level

Question 7

Acclimatization

Answer 7

the adaptations produced by a change in the natural enviroment

Question 8

Acclimation

Answer 8

The adaptation produced in a controlled lab environment as in chambers the can simulate high altitude

Question 9

Reduction in PO2 and accompanying arterial hypoxia

Answer 9

Speeds up the immediate physiologic adjustments to altitude and longer-term acclimatization

Question 10

What can cause a shift in OxyHb dissociation curve?

Answer 10

Varibles that effect curve = Temp, pH, CO2, 2,3 BPG
Shift to the RIGHT = decrease pH, increase in CO2 and temperature

Shift to the LEFT = increase in pH, decrease in CO2 and temperature

Question 11

What can cause a shift in OxyHb dissociation curve?

Answer 11

Varibles that effect curve = Temp, pH, CO2, 2,3 DPG
Shift to the RIGHT = decrease pH, increase in CO2 and temperature

Shift to the LEFT = increase in pH, decrease in CO2 and temperature

Question 12

What is 2,3 DPG?

Answer 12

Biphophoglycerate, which is a byproduct of glycolyisi in RBC. Production increase during hypoxia. Binds to deoxygenated forms of Hb and assists in unloading O2 from Hb

Question 13

Moderate altitude does not decrease short-term anaerobic performance or sprints, Why? What is the primary energy system?

Answer 13

anaerobic performance does not utilize O2 to functionast less than 2 minutes of activity. Utilizes phosophe creatine (0-10 sec), glycolysis (45 sec - 2/2.5 min) Myocondrial respiration is aerobic respiration anaerobic respiration and glycolysis.

Question 14

Can sprinting times or anaerobic power event improve at altitude?

Answer 14

Think about air density, is it high or low? What does this do to air resistance or drag?

Less resistance or drag occurs at high altitude

Question 15

In the transition from moderate to hight altitude arterial PO2 values are on what part of the OxyHb dissociation curve?

Answer 15

The steep part of the curve

Question 16

How does high elevation effect oxygen loading?

Answer 16

O2 loading of Hb decreases and physical activity becomes difficult to sustain

Question 17

How is mild aerobic activities effected by moderate to high altitude changes?

Answer 17

This change in altitude negatively effects Hb oxygenation and O2 transport capacity

Question 18

Sudden exposure to 4300 m would cause a…

Answer 18

32% reduction in aerobic capacity compared to sea level values

Question 19

At what elevation is supplemental O2 typically required?

Answer 19

At altitudes above 5200m / 1700 ft

Question 20

What happened at 5500m/1800ft?

Answer 20

Arterial PO2 averages 38 mm Hg

Hb maintains only 73% O2 saturation

Question 21

What is the PO2 and arterial blood O2 saturation at Mt Everest summit

Answer 21

arterial PO2 = 25 mm Hg

blood O2 saturation = 58%

Question 22

What would happen to an unacclimatized person is they were placed on mt. Everest summit?

Answer 22

Unconscious within 30 sec

Question 23

what is the simulated summit acclimatized man?

Answer 23

average male VO2max decreases by 70% form 4.13 L/min to 1.17 L/min.

This is equivalent to sedentary male 80 you or a female cardiac patient

Question 24

Pugh et al (1964) VO2max in relation to terrestrial elevation

Answer 24

VO2max decreased from seal level upward and declined steeply above 6000 m to reach an average of 1.42 L/min @ 7440 m

Question 25

Respiratory exchange ratio during graded exercise at sea level and 5800m

Answer 25

Shows a tendency for a higher respiratory exchange ratio (RER) at all exercise levels at 5800 m than at sea level RER increased vertically at 5800m This is indicative of hyperventilation and increased La- at high altitude

Question 26

Altitude acclimatization

Answer 26

adaptive responses in physiology to high altitude. Metabolism that improve tolerance to altitude hypoxia. Corrective responses to altitude occurs almost immediately while other adaptions take weeks or even months.

Question 27

How long can someone retain the benefits of altitude acclimatization?

Answer 27

Many of the beneficial submaximal exercise responses associated with 16 days of acclimatization at 4300m

Question 28

Immediate and longer-term adjustments to altitude hypoxia - PULMONARY ACID-BASE

Answer 28

Immediate Hyperventilation Bodily fluids become more alkaline due to reduction in CO2 (H2CO3) with hyperventilation Longer-Term Hyperventilation Excretion of base (HCO3-) via the kidneys and concomitant reduction in alkaline reserves

Question 29

Immediate and longer-term adjustments to altitude hypoxia - PULMONARY ACID-BASE

Answer 29

Immediate Hyperventilation Bodily fluids become more alkaline due to reduction in CO2 (H2CO3) with hyperventilation Longer-Term Hyperventilation Excretion of base (HCO3-) via the kidneys and concomitant reduction in alkaline reserves

Question 30

Immediate and longer-term adjustments to altitude hypoxia - CARDIOVASCULAR

Answer 30

Immediate Increase in sub maximal heart rate Increase in sum maximal cardiac output Strike volume remains the same or decreases slightly Maximum cardiac output remains the same or decreases slightly ``` Longer-term Submaximal heart rate remains elevated Submaximal cardiac output falls to or below sea-level values Stroke volume decreases Maximum cardiac output decreases ```

Question 31

Immediate and longer-term adjustments to altitude hypoxia -HEMATOLOGIC

Answer 31

No immediate effects ``` Longer-Term Decreased plasma volume Increased hematocrit increased hemoglobin concentration Increased total number or RBC ```

Question 32

Immediate and longer-term adjustments to altitude hypoxia -LOCAL SYSTEMS

Answer 32

``` Possible increased capillarization of skeletal muscle Increased RBG, 2,3-DPG Increased mitochondrial density Increased aerobic enzymes in muscles loss of body weight and lean body mass ```

Question 33

At an elevation of 2300 m (2546 ft) & higher how doe the moody immediately reacts to altitude

Answer 33

At 2300 m the body needs to adapt to thinner air and decreased PO2 1. increase in the respiratory drive to produce hyperventilation 2. Increase in blood flow during rest & submaximal exercise

Question 34

Hyperventilation in response to altitude changes

Answer 34

Hyperventilation is the first line of defense against high altitude Peripheral Chemoreceptors sense low PO2 levels. Receptors signal an increase of alveolar ventilation by hyperventilation. Hyperventilation increased O2 loading in the lungs

Question 35

Cardiovascular response to High Altitude

Answer 35

Increase resting BP submit HR and Q increase as much as 50% SV remains unchanged Increased submit exercise blood flow at altitude compensates for arterial desaturation

Question 36

Comparison of oxygen cost and relative strenuousness of submacimal exercise at seal level and high altitude

Answer 36

While O2 cost of submax exercise at 100 W of power output at sea level & high altitude remains unchanged at about 2.0 L/min, the relative strenuousness of the effort increases at altitude Submax exercise representing 50% of sea level VO2max = 70% of VO2 max at 4300 m

Question 37

Comparison of oxygen cost and relative strenuousness of submacimal exercise at seal level and high altitude

Answer 37

While O2 cost of submax exercise at 100 W of power output at sea level & high altitude remains unchanged at about 2.0 L/min, the relative strenuousness of the effort increases at altitude Submax exercise representing 50% of sea level VO2max = 70% of VO2 max at 4300 m

Question 38

Catecholamine Response to Altitude

Answer 38

NE activity progressively increases over time during rest and exercise with altitude *Increased HR/BP at altitude coincide with a steady rise in plasma level of NE

Question 39

NE levels peak after what day of high altitude exposure?

Answer 39

NE levels peak after day 4 and then remain stable

Question 40

NE levels peak after what day of high altitude exposure?

Answer 40

NE levels peak after day 4 and then remain stable

Question 41

How does the body compensate for the blood's decreased O2 content?

Answer 41

By increasing Blood flow (Q)

Question 42

How doe the body increase blood flow (Q)?

Answer 42

In high altitude the body increases blood flow (Q) by increasing HR, SV remains the same

Question 43

What is the difference between Sea level & altitude submax exercise O2 consumption?

Answer 43

Due to the increase of blood flow (Q) O2 consumption remains basically the same between seal level and altitude

Question 44

What happens to arterial O2 saturation during high altitude submaz exercise?

Answer 44

Arterial O2 saturation decreases from 96% at sea level to 70% at altitude during all exercise intensities

Question 45

What happens during max effort at a short-term altitude exposure (<7days)

Answer 45

Ventilatory and circulatory adjustments fail to compensate for the depressed arterial O2 content

Question 46

What happens after each 1000 m increase in altitude?

Answer 46

For each 1000 m increase in altitude there is a proportionate increase in exercise ventilation volume

Question 47

What happens when exercise O2 consumption exceeds 2.0 L/min?

Answer 47

When O2 levels exceed 2.0 L/min, pulmonary ventilation increased disproportionately at progressively higher elevation

Question 48

What are the complication of body water evaporation due to the ambient air of the mountainous regions?

Answer 48

With the mountainous regions remain cool and dry the considerable body water evaporates as inspired air becomes warmed and moistened in the respiratory passages, This loss of body water can lead to moderate dehydration - symptoms of dryness of the lips, mouth, and throat.