Lecture 13 - Maximal oxygen uptake: determinants and limits Flashcards
there is a linear relationship between the oxygen uptake and the
power output
what happens to VO2 max with ageing?
tends to go down
part is due to a genuine response to aging but most is reduced physical activity levels
what is the frailty threshold?
15-16 ml/kg/min
below here, you’re starting to get in areas where its hard to do daily activities
What is the heritability of VO2 max?
shown to be a close correlation in monozygotic twinsthe
max heritability has been estimated at 51%
half genetics, half dependent on how physically active you are
What are the potential limitations to maximal VO2?
respiration
central circulation - haem concentation, CO
peripheral blood flow - peripheral density, vascularity
metabolism
- substrate delivery
muscle mass
[mitochondria]
In the leg, it has been shown that VO2 max can be limited by…
oxygen delivery
Muscle mitochondrial capacity exceeds _____ delivery in humans
oxygen
If you want to increase your VO2max via oxygen delivery, what can you do?
blood dope - take erythropoid and increase Haem mass
Increase CO Max - by doing endurance training
When may the respiratory system be a limiting factor for VO2max?
if you go to altitude, if you have pulmonary disease,
if you’re a highly trained athlete that has high pulmonary blood flow it creates a diffusion limitation
but in most healthy subject pulmonary will not be a limiting factor
As you approach VO2max the ___ delivery does become limiting
oxygen delivery
What is acute hypervolemia?
increased maximal SV and CO
achieved by expanding blood volume in untrained.
not as effective in trained subjects as their blood volume is already expanded
people who have high VO2MAX, there are differences in not only stroke volume, but..
blood volume
inceraased albumen synthesis among genetics factors that can increase blood volume
For a small muscle mass, if you exercise it you can increase the CO enough to give it all the blood it wants.
But as soon as you increase the muscle mass you have to constrain the blood flow, why?
as you can’t afford to give all the blood to the contracting muscle - you’d faint
the maximal cardiac output is a maximal value
Yes, you can increase it with training but its a maximal value that limits your capacity to..
deliver blood to contracting muscles
VO2 MAX
If the pericardium is cut, what happens?
higher CO and VO2Max
found in dog studies
