Ch 24 - Exercise at Medium & High Altitude Flashcards
What is the main physiological challenge does high altitude pose?
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
What is ambient air PO2?
20.93 or 21%
Air density decreases when…
one ascends above sea level
What is the barometric pressure to sea level?
Pb = 760 mm Hg
T of F: PO2 of air decreases directly with the fall in barometric pressure
True: PO2 = 0.2093 x Pb
Stress of Altitude at sea level vs mt. Everest
Ambient PO2 at seal level = 159 mm Hg
Mt. Everest PO2 = 50 mm Hg
This is 30% of the O2 available at sea level
Acclimatization
the adaptations produced by a change in the natural enviroment
Acclimation
The adaptation produced in a controlled lab environment as in chambers the can simulate high altitude
Reduction in PO2 and accompanying arterial hypoxia
Speeds up the immediate physiologic adjustments to altitude and longer-term acclimatization
What can cause a shift in OxyHb dissociation curve?
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
What can cause a shift in OxyHb dissociation curve?
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
What is 2,3 DPG?
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
Moderate altitude does not decrease short-term anaerobic performance or sprints, Why? What is the primary energy system?
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.
Can sprinting times or anaerobic power event improve at altitude?
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
In the transition from moderate to hight altitude arterial PO2 values are on what part of the OxyHb dissociation curve?
The steep part of the curve
How does high elevation effect oxygen loading?
O2 loading of Hb decreases and physical activity becomes difficult to sustain
How is mild aerobic activities effected by moderate to high altitude changes?
This change in altitude negatively effects Hb oxygenation and O2 transport capacity
Sudden exposure to 4300 m would cause a…
32% reduction in aerobic capacity compared to sea level values
At what elevation is supplemental O2 typically required?
At altitudes above 5200m / 1700 ft