Week 8 - Exercise and Altitude Flashcards
What is altitude?
distance above sea level
At high altitude, what happens to air density?
lower air density
What is the effect of lower air density at altitude on high-speed movement and sprint performance?
offers less resistance to high-speed movement, and sprint performances are either not affected or improved
1964 Tokyo Olympics –> 1968 Mexico Olympics
How does altitude influence short-term anaerobic performance?
- Lower air resistance may improve performance
- Lower PO2 at altitude should have no effect on performance (oxygen transport to muscle doesn’t limit performance)
How does altitude influence long-term aerobic performance?
- Lower PO2 results in poorer aerobic performance as its dependent on oxygen delivery to the muscle.
What is the relationship between atmospheric pressure and altitude?
Atmospheric pressure decreases at higher altitude
Boyle’s law of - gas volume and pressure
gas volume inversely proportional to its pressure
At high altitude we get the … percentages of O2, CO2, N2 in the air but we get a … partial pressure of O2, CO2, N2.
Same + Lower
Why is the partial pressure of inspired oxygen (PO2) decreased at higher altitudes?
due to lower barometric pressure
Hypoxia
low PO2 (low partial pressure of oxygen - occurs at high altitude)
Normoxia
normal PO2 (sea level)
Hyperoxia
High PO2
Hypoxaemia
Low levels of oxygen in the blood
Exposure to hypoxia results in a reduction in what? What does this disruption in homeostasis trigger?
Exposure to hypoxia directly results in a reduction in arterial oxygen pressure (PaO2). This disruption in homeostasis triggers neuroendocrine responses that help regulate important adjustments in key physiological systems.
What is the time of useful consciousness at altitude?
60 seconds
Identify the ventilatory and CV short-term adjustments to altitude.
Immediate response is to get in more O2 molecules!
Ventilation changes
* Hyperventilation (chemoreceptors)
* Raises alveolar O2
* Lowers alveolar CO2
* Causes alkalosis and diuresis (HCO3-)
Cardiovascular changes
* Increased resting heart rate and cardiac output
What are the changes in V02max with increasing altitude?
As altitude increases, VO2max is reduced (less able to uptake oxygen and utilise it)
What is the effect of altitude on the ventilatory response to sub-maximal exercise?
Increases ventilation at the same workload due to reduction in number of O2 molecules per litre of air, but Pao2 falls.
What is the effect of acute exposure to altitude on the CV response to sub-maximal exercise?
HR and cardiac output increases during submaximal exercise as there is a lower oxygen content of arterial blood and increased SNA.
What is the effect of high altitude on the HR response to maximal exercise?
Maximal HR response to exercise is attenuated at attitude due to the activation of the parasympathetic NS - act as cardioprotective?
What is the short-term effect of altitude on a-vO2 difference?
decreased
What happens to lactate production during maximal efforts at high altitude?
Lactate production isn’t higher at altitude during maximal effort (Lactate paradox)
What is the beneficial effect of acclimatization?
Prolonged exposure to altitude increases oxygen uptake at sea level.
Describe the CV long-term adjustments to altitude hypoxia.
– Heart rate increased (increased sympathetic
nerve activity)
– Stroke volume decreased
– Cardiac output unchanged or slightly decreased
– Maximal cardiac output decreased
Describe the Vascular/cellular (local) long-term adjustments to altitude hypoxia.
– Increased skeletal muscle capillarization
– Increased RBC 2,3-DPG
– Increased myoglobin in the muscle
- Increased mitochondrial density
- greater a-vO2
– Increased oxidative enzyme activity
– Loss of body weight and lean body mass
Explain the haemotologic (blood) long-term adjustments to altitude hypoxia.
– Decreased plasma volume
– Increased haematocrit, haemoglobin and RBC
number
- Increased Bohr shift
Explain the pulmonary acid-base long-term adjustments to altitude hypoxia.
– Hyperventilation
– Excretion of base (HCO3-) via kidneys
Purpose of high altitude training
perform better at sea level
Benefits of high-altitude training
- Increased RBC mass
- Increased skeletal muscle capillarization
- Increased oxidative enzyme activity
- HR increased, SV decreased
Detriments of high-altitude training
- Increased blood viscosity
- Loss of training intensity (detraining effect?)
- Reduced muscle mass
- Increased ventilatory response
What is a solution to the detriments of high altitude training?
Live high, train low concept
e.g. tents (hypoxicators) believed to be an effective performance enhanced.
Describe the “Live high, train low” concept.
- Live at high altitude may elicit an increased in RBC mass via EPO (erythropoietin - important hormone in making RBC) and this may lead to an increased V02max.
- Train at low altitude maintains high interval training velocity.
Compared to the heart rate value measured at sea level, when a subject works at the same work rate (e.g., 150 watts) at 3,000 meters altitude, what happens to heart rate?
its higher
