Exercising at High Altitude

Question 1

How does high altitude effect PO2 in ambient air?

Answer 1

PO2 is decreased, % of O2 is decreased

Question 2

How does high altitude effect O2 saturation of Hb in pulmonary capillaries?

Answer 2

decreases as you go higher in altitude
- small changes until at 3048m
- from mod to high altitude, Hb’s oxygenation dramatically decreases & negatively effects mild-intensity aerobic exercise

Question 3

How does high altitude effect VO2 max?

Answer 3

decreases it to about 2.8L/min compared to 4L/min at sea level

Question 4

Explain the oxygen cascade at sea level & 4300m

Answer 4

@Sea level:
PO2 =
149 mmHg (inspired air)
103 mmHg (alveolar air)
100 mmHg (arterial blood)
40 mmHg (mixed-venous blood)

@4300m:
96 mmHg (inspired air)
46 mmHg (alveolar air)
42 mmHg (arterial blood)
27 mmHg (mixed-venous blood)

Question 5

What are the immediate physiological adjustments to exercise at high altitude?

Answer 5

Immediate:
1. Pulmonary acid-base (most important)
= hyperventilation - increase in respiratory drive
(result of reduced PaO2)
- fluids become alkaline

2. increase in blood flow during rest & sub-maximal exercise
   - HR & Q increase
   - SV stays the same
   - Max Q stays the same or decrease slightly

Question 6

Symptoms, causes, & treatment for acute mountain sickness

Question 7

Symptoms, causes, & treatment for high-altitude pulmonary edema

Question 8

Symptoms, causes, & treatment for high-altitude cerebral edema

Question 9

Describe the lactate paradox & possible causes

Answer 9

initially, greater lactate accumulation for a given exercise compared to sea-level values (due to anaerobic metabolism & altitude hypoxia).
after weeks, there is lower blood lactate levels when doing the same exercise.

Why?
1. reduced output of epinephrine during exercise
(reduced glucose mobilization from liver reduced lactate formation)

2. overall reduced CNS drive, = reduced capacity for all-out effort

Question 10

What factors affect the time course for altitude acclimatization

Answer 10

1. depends on elevation
2. takes 2 weeks to adapt to 2300m, every 610m after needs an additional week

(you never fully acclimatize)

Question 11

graph the relationship between increasing altitude exposure & decrease in VO2 max

Answer 11

small decline until 589m, then 7-9% decrease per 1000m until 6300m. then declines rapidly
- @7000m, VO2 max is half of sea level

so, as elevation increases, VO2 decreases

Question 12

What impacts circulatory function that offset the benefits of altitude acclimatization on O2 transport capacity

Answer 12

Low VO2max
- lower max HR
- lower SV offsets hematologic benefits

Question 13

Does altitude training produce greater improvements than sea-level training on sea-level exercise performance

Answer 13

No, because VO2 is important factor and it never gets improved at altitude

Question 14

What does “live high train low” mean?

Question 15

Define Acclimatization

Answer 15

adaptations produced by changes in the natural environment (either through change in season or place of residence)

Question 16

Acclimation

Answer 16

adaptations produced in a controlled laboratory environment

Question 17

Define altitude acclimatization

Answer 17

adaptive responses in physiology & metabolism that improve tolerance to altitude hypoxia

Question 18

What is increased altitudes impact on the body & its systems?

Answer 18

Long term:
1. Cardiovascular response
- resting BP increases in early stages
- submaximal HR & Q = 50x more than sea level
- SV does not change
- increased blood flow to make up for arterial desaturation

2. Catecholamine response
   - increase of sympathoadrenal activity (@rest & exercise)
   - epinephrine rates & plasma levels rise –> increased BP & HR
   - norepinephrine increases greatly at altitude (@day4), way more than epinephrine
3. Fluid Loss
   - cool/dry air evaporates, body water evaporates
   - leads to mod dehydration, dryness of lips/mouth/throat
   - critical during exercise because of large daily total sweat loss & ventilation
4. Sensory Functions
   - after 3048m, the following decrease:
   25% light sensitivity/attention/pursuit tracking/reaction time/coding, 30% visual activity, 33% postural instability, 20% recall, 15% cognition

Question 19

What are the longer-term physiological adjustments to exercise at high altitude?

Answer 19

1. pulmonary acid-base = hyperventilation (increases PaO2, but makes body alkaline)
2. cardiovascular
   = elevated submaximal HR
   =Q falls to or below sea-level
   = SV decreases
3. Hematologic
   = decreased plasma volume (so, o2 content increases in arterial blood)
   = increased Hb, hematocrit, & total #RBC
4. Local
   = increase in RBC 2,3-DPG, mitochondrial density, aerobic enzymes in muscle, loss of body weight & lean body mass
   = oxygen dissociation curve right-shift

Question 20

Small exercise improvements at altitude

Answer 20

1. increased minute ventilation
2. increased arterial oxygen saturation & cellular aerobic functions
3. lower blood lactate response