L34 Altitude

Question 1

Explain the relationship between barometric pressure, altitude and the partial pressure of oxygen (PO2

Answer 1

At altitude there is a reduced barometric pressure an therefore a reduced partial pressure of oxygen even though the concentrations are the same for all the gas.
Hypoxia at altitude

Question 2

Explain the physiological challenges to work and exercise at high altitude

Answer 2

• Light-headedness, headache
• Insomnia, nausea, vomiting, pulmonary
• Dyspnoea, anorexia, GI disturbances
• Lethargy

Question 3

Explain the relationship between VO2max (cardiac output, a-vO2 diff) and altitude, and describe how this may be altered following acclimatisation

Answer 3

At Everest your vo2 max would expect to fall by 70%. It will begin to increase however as you got more and more used to working at altitude

Question 4

Describe the short and long-term effects of altitude on ventilation and the cardiovascular system (e.g., heart rate, stroke volume, cardiac output)

Answer 4

SHORT TERM
Ventilation changes → hyperventilation (chemoreceptors)… Raises alveolar O2… Lowers alveolar Co2… Causes alkalosis and diuresis (HCO3)
-Cardiovascular changes → increased in resting heart and cardiac output

LONG TERM

• Cardiac output and stroke volume is lower. Oxygen consumption is the same. So Co is lower but to have the same O2 consumption, the A-vO2 difference must be the same.
• Minute ventilation increases after 4 days by more, the higher altitude you are.

Question 5

List the vascular and cellular changes which occur in the blood and circulation at high altitude

Answer 5

• Increased capillarisation
• Increased myoglobin in muscles
• Increased aerobic enzymes
• Muscle mitochondrial density does not increase
• A-vo2 difference during exercise, falls with short term exposure but widens following acclimatization.
• Increases lactate consumption and oxidation by active muscle

Question 6

Describe the effect of 2,3-DPG on the oxygen-haemoglobin dissociation curve

Answer 6

• Hyperventilation causes alkalosis which shifts oxygen dissociation curve to the left. BUT an increase in 2,3 DPG in red blood cells shifts the curve to the right and causes increased Bohr shift.

Question 7

Outline the “live high, train low” concept

Answer 7

Live at high altitude
- may elicit and increase in red blood cell mass via PEO = Increase in VO2 max
- 22hr or more at 2000-2500 m required or stimulated altitude of 2500 - 3000 for 12-16 hours per day
- Intermittent hypobaric hypoxia - like 3 hours a day 5 day a week at 4000-500m
Train at low altitude
- Maintain high interval training velocity