Week 8 - Exercise and altitude Flashcards
Whats Boyles Law
Gas volume is inversely proportional to its pressure
What is the impact on barometric pressure and altitude
Same percentages of o2, co2 and n2 in the air.
Lower partial pressure of o2, co2 and n2
Whats hypoxia
Low PO2 (altitude)
Whats Normoxia
Normal PO2 (sea level)
Whats Hyperoxia
High PO2
Whats hypoxemia
Low levels of oxygen in the blood
Whats the impact of exposure to hypoxia
Results in a reduction of arterial oxygen pressure (Pao2). This disruption in homeostasis triggers neuroendocrine responses that help regulate important adjustments in key physiological systems
Explain the oxygen transport cascade
Ambient air -> lungs -> hemoglobin-> cardiac output ->muscle blood flow -> oxygen extraction -> cellular metabolism
Whats an immediate response to altitude
More o2 molecules recruited
What are the ventilation changes to altitude
Hyperventilation (chemoreceptors)
Raises alveolar o2
Lowers alveolar co2
causes alkalosis and diuresis (HCO3)
What are the cardiovascular changes to altitude
Increased resting heart rate and cardiac output
What are some other effects of being at altitude
Cold / dry air means reduced humidity
Dehydration
UV light (sunstroke, blindness)
Whats the effect of altitude on the ventilatory response to sub maximal exercise
Increased ventilation for same workload
Whats the effect of acute exposure to altitude on the cardiovascular response to sub maximal exercise
Heart rate increased during submaximal exercise - lower oxygen content and increased SNA
Whats the effect of high altitude on the heart response to maximal exercise
At max cardiac strain is reduced.
Lactate production is also isnt higher at altitude at maximal intensity
Maximal heart rate response to exercise is attenuated at altitude
Evidence that activation of PNS limits maximal heart rate response to exercise at altitude
Parasympathetic blockade (glycopyrrolate) restores maximal heart rate response to exercise (closed triangles)
Whats the effect of altitude acclimatisation on the cardiovasucular response to sub maximal response
More o2 in the blood improves o2 extraction capacity = less reliance of central delivery
What are the blood changes due to high altitude
(ON SHEET)
Polycythemia due to increased erythoprotein (EPO)
Decreased plasma volume
Hyperventilation causes alkalosis which shifts the oxyhaemoglobin disocciation curve to the left, but increase in 2,3 diphosphoglycerate in RBC’s shifts ODC ro right and causes increased Bohr shift
What are the vascular / cellular changes to high altitude
increased capilarization - largely due to reduction in muscle mass
Increased myoglobin in muscles
Increased aerobic enzymes (citrate synthase)
However muscle mitochindrial density does not increase
A-VO2 difference during exercise, falls with short-term exposure but widens following acclimatisation
Increased lactate accumulation and oxidation by active muscle
What are the benefits to high altitude training
Blood changes (red cells mass) some ceullular changes, some circulatory changes
What are the detriments to altitude training
Blood changes (viscosity), cardiovascular changes, loss of training intensity, reduced muscle mass, increased ventilatory response
Whats a solution to the detriments of altitude training
Live high, train low? Tents (hypoxicators) believed by many to be an effective performance enhancer
Whats the effect of live high train low
May elicit an increase in red blood cell mass via EPO leads to increases VO2 max
>22hr/day at 2,000-2,500m required or stimulated altitude of 2,500-3,000m for 12-16hr/day
Intermittent hypobaric hypoxia. E.g 3hr/day, 5 days/wk at 4,000-5,000m
Train at low altitude. Maintain high interval velocity
