Lecture 13

Question 1

Gaseous pressure in space vs sea level

Answer 1

Space: ~0mmHG
Sea level: 760mmHG

Question 2

How are lung O2 pressures affected when exercising at altitude

Answer 2

Lung PO2 decreases, decreasing O2 available for the body’s tissues

Question 3

Pressure changes from ambient air to lung

Answer 3

Usual ambient air= 160mmHG, Lung=100mmHG
-Air is humidified in the respiratory tract, and
water vapour has a low partial pressure
-Even lower at altitude

Question 4

How does altitude affect the OxyHb saturation?

Answer 4

After a certain altitude, OxyHb saturation drops rapidly

Question 5

Threshold at altitude formula

Answer 5

VO2 max at altitude x Threshold % at altitude
Ex: VO2 max at altitude=42mlO2/kg/min
Threshold at altitude=65% of max
Therefore: 42 x 65% = 27.3mlO2/kg/min

Question 5

Effect of altitude on VO2 max threshold and sustainable work formulas

Answer 5

VO2 max= 45mlO2/kg/min
Mass: 75kg
Max at peak: 70% of max
Threshold at peak: 60% of max at peak
VO2 at rest: 263mls

Therefore:
Absolute VO2 at sea level = 45 x 75kg = 3375mls
Max at peak = 3375 x 70% = 2362.5mls
Threshold at peak = 2362.5 x 60% = 1417.5mls
Watts available at peak = (1417.5-263)/10= 115W