Exercise and altitude Flashcards
Do high speed movements benefit from high altitude?
Yes - The lower air density at altitude offers less resistance to high-speed
movement, and sprint performances are either not affected or are improved.
Does endurance performance benefit from high altitude?
No - performance demands that is more dependent on O2 delivery to muscle
What does Boyle’s Law tell us?
Gas volume inversely proportional to its pressure
e.g., at higher pressure, air starts to spread out (still same pressure of O2)
What does hypoxia mean?
Low PO2
What does normoxia mean?
Normal PO2
What does hyperoxia mean?
High PO2
What does hypoxaemia mean?
Low levels of blood O2
What is the effect of altitude on environmental and physiological variables?
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
Short-term adjustments to altitude - ventilation changes?
- Hyperventilation (chemoreceptors)
- Raises alveolar O2
- Lowers alveolar CO2
- Causes alkalosis and diuresis (HCO3-)
Short-term adjustments to altitude - CV changes?
Increased resting HR and Cardiac Output
Cold/dry air (reduced humidity), dehydration, UV light (sunstroke, blindness)
What is the immediate physiological response to altitude ?
Get in more O2 molecules
What happens to VO2max with increasing altitude?
Aerobic power is extremely reduced at high altitudes
What is the effect of high altitude on the HR response to maximal exercise?
- Cardiac strain is reduced
Lactate production also isn’t higher at altitude at max effort (lactate paradox) - Max HR response to exercise is attenuated at altitude
- Evidence that activation of parasympathetic nervous system limits maximal heart rate response to exercise at altitude.
What is the effect of altitude on the ventilatory response to sub-maximal exercise?
Increased ventilation for same workload
What is the difference in minute ventilation between acute and longer term response to altitude?
Minute ventilation increases more as a longer term response to altitude
Altitude acclimatisation - why does CO fall if HR stays roughly the same?
Fick equation: VO2 = cardiac output x a-vO2 difference.
More O2 in the blood improves O2
extraction capacity = less reliance of
central delivery (i.e. less cardiac strain).
What hormone typically increases O2 carrying capacity of blood cells?
EPO
What effect does a decrease in plasma volume have?
Helps concentrate haemoglobin (Hb)
In terms of a timeline, what order do events happen when spending time at altitude?
- Reduction in plasma volume occurs very quickly upon exposure to high altitude
- This increase O2 carrying capacity of blood by concentrating existing RBC
- This = increase Hematocrit
- Hypoxia stimulates synthesis + resynthesis of EPO from kidneys, which = true increase in RBC volume during more prolonged altitude acclimatization.
Name some vascular/cellular changes to high altitude training?
- Increased capillarisation
- Increased myoglobin in muscles
- Increased aerobic enzymes (citrate synthase)
- However, muscle mitochondrial density probably does not increase
- a-vO2 difference during exercise, falls with short-term exposure, but widens following acclimatisation
- Increased lactate consumption and oxidation by active muscle
What are the benefits of high altitude training?
Blood changes (red blood cell mass), some cellular changes, some circulatory changes.
What are the detriments to high altitude training?
- blood changes (viscosity)
- CV changes
- Loss of training intensity (detraining)
- Reduced muscle mass
- Increased ventilatory response
What is the solution to the detriments high altitude training can cause?
Live high, train low? Tents (hypoxicators) believed by many to be an effective performance enhancer.
What does the ‘live high, train low’ method involve?
Live at high altitude (may cause increase in RBC mass - via EPO).
- >22hr/day at 2000-2500m required
- Intermittent hypobaric hypoxia (3hr/day, 5 days/wk at 4-5k m)
- Train at low altitude (maintain high interval training velocity)
What are things to consider when doing altitude training?
- Depends on individual (low vs high responder, individual differences may be due to training state before arriving at altitude)
- Pre-testing to determine likelihood of an effect?
- Think about what’s best for athlete (benefit or summer from camp?)
