Altitude Flashcards
In 1978 what was the estimated VO2 max on Everest thought to be and why?
15 ml/kg/min due to miscalculation of barometric pressure at the Everest summit.
Why do successful climbers have a better capacity for hyperventilation?
To drive down PCO2 and H+ in the blood allowing for more O2 to bind with hemoglobin at the same PO2
What are the effects of climbers having to contend with loss of appetite?
Weight loss and reduction of both type 1 and 2 muscle fiber diameter
What happens to the percentage of oxygen in the air as altitude increases?
The % of O2 in the air does not change
What happens to the partial pressure of oxygen in the air as altitude increases
The partial pressure of oxygen decreases as altitude increases
What happens to barometric pressure as altitude increases?
Barometric pressure decreases
What happens to the diffusion gradient in the tissues at altitude?
Diffusion gradient at the tissues is much lower making it harder for the muscle to receive oxygen as quickly
What effect does altitude have on the hemoglobin oxygen dissociation curve?
Low PO2 Hypoxia causes shift to the left; Easier unloading
What three components make up arterial oxygen content
- Saturation
- Hemoglobin concentration
- Partial pressure of Oxygen in the arteries
What happens to VO2 max at higher altitudes?
Decrease in VO2 max
Higher altitude changes to oxygen
Lower partial pressure of oxygen in air means less oxygen in the alveoli, less oxygen in the arteries, carrying less oxygen and ultimately less oxygen being delivered to the muscles
Why do trained individuals have a larger decline in % VO2 max
At altitude there is a lower partial pressure of oxygen in the alveoli but trained individuals have a higher stroke volume and shorter Pulmonary capillary transit time so they will have less oxygen sent to the tissues
What can protect VO2 max decline
Higher Hb-O2 affinity
What is the Intrapulmonary arteriovenous anastomoses
Blood is redirected through this shunt and blood wont be oxygenated but the pressure is decreased
Patent foramen ovale
Foramen ovale remains open after birth when it is supposed to close
Risks of having PFO at altitude
More at risk for venous blood to pass to the atrium and bypassing the lungs
What happens to heart rate during submaximal exercise at altitude
Heart rate increases due to lower PO2 triggering increases in epinephrine causing vasodilation in the peripheries and vasoconstriction in the lungs
What happens to ventilation at submaximal exercise in altitude
Ventilation increases as peripheral chemoreceptors sense lower PO2
How does altitude affect short term anaerobic performance?
Lower PO2 at altitude doesn’t effect performance because O2 transport to the muscles does not limit performance in these events (non-oxidative sources)
What is the benefit of short-term anaerobic performance at altitude?
Lower air resistance may improve performance
Altitude impact on long-term aerobic performance
Lower PO2 decreases performance as muscles are dependent on oxygen being delivered to function
What happens to plasma volume upon initial arrival to altitude?
There is a decrease in SV leading to a decrease in plasma volume due to respiratory water loss and increased urine production; leads to increased hematocrit
What happens to plasma volume after a few weeks at altitude?
Plasma volume will return to normal if adequate fluid is ingested.
What three things happen to acclimatize to high altitude?
- Production of more red blood cells
- Greater oxygen saturation
- Hyperventilation
