Exercise and Altitude W8 Flashcards
What are the long-term effects of altitude on aerobic performance?
Lower PO2 results in poorer aerobic performance
(dependent on oxygen delivery to muscle)
What are the short-term effects of altitude on anaerobic performance?
Lower air resistance may improve performance
Lower PO2 at altitude should have no effect of performance
What happens to atmospheric pressure at higher altitude?
It decreases
What is Boyle’s Law?
Gas volume inversely proportional to it’s pressure
What is altitude?
Lower air density at higher altitude (air pressure)
What is hypoxia?
Low PO2 (altitude)
What is normoxia?
Normal PO2 (sea level)
What is hyperoxia?
High PO2
What is hypoxaemia?
Low levels of oxygen in the blood
What are the short-term ventilation changes to altitude?
Hyperventilation (chemoreceptors)
Raises alveolar O2
Lowers alveolar CO2
Alkalosis
What are the short-term cardiovascular changes to altitude?
Increased resting heart rate and cardiac output
What are the physiological responses to exercise after being at high altitude?
Reduced partial pressure of O2
Reduced VO2max
Reduced maximal heart rate
Reduced a-VO2 difference
Increased heart rate and cardiac output
Increased ventilation
How is VO2max calculated?
FICK’S EQUATION
VO2=CO x a-VO2 difference
Why does ventilation increase during altitude exercise?
Due to reduction in number of O2 molecules per litre of air while PaO2 falls
Why does heart rate and cardiac output get higher during sub-maximal workloads at altitude?
Due to lower oxygen content of arterial blood
Why does maximal heart rate become lower after altitude exposure?
Due to parasympathetic (vagal) activation
What are the blood changes to altitude?
Polycythaemia
Decreased plasma volume
What is polycythaemia?
Increased production of red blood cells
Why does red blood cell volume increase at altitude?
Hypoxia stimulates the synthesis and resynthesis of erythropoietin (EPO)
What are the vascular/cellular changes to altitude?
Increased capillarisation
Increased myoglobin in muscles
Increased aerobic enzymes
Increase lactate consumption and oxidation by active muscles
What are the long-term pulmonary acid-base adjustments to hypoxia?
Hyperventilation
Excretion of base (HCO3) via kidneys
What are the long-term cardiovascular adjustments to hypoxia?
Heart rate increased
Stroke volume decreased
Cardiac output unchanged or slightly decreased
Maximal cardiac output decreased
What are the long-term haematologic adjustments to hypoxia?
Decreased plasma volume
Increased:
- Haematocrit
- Haemoglobin
- Red Blood Cell number
What are the long-term localised adjustments to hypoxia?
Increased skeletal muscle capillarization
Increased RBC 2,3-DPG
Increased oxidative enzyme activity
Loss of body weight and lean body mass
