Ok science nerds, in my quest to wholly understand VO2 consumption, I read an interesting article the other day. It basically stated that through endurance training, the majority of change in tolerance to exercise (in athletes) takes place systemically, rather than centrally. Instead of changing lung function, the body increases the amount of mitochondria in your cells, as well as the density of your capillary beds. Increased mitochondria production leads to faster, more efficient oxygen uptake (requiring less energy for the same amount of glycolysis or ATP production). Increased density at the capillary beds apparently has a few effects. First, it allows blood to pass through slower, which increases the amount of time for oxygen/nutrient transfer. And second, it provides a larger surface contact area, which also allows for a greater uptake of nutrients.
Another interesting point of the article stated that after a significant endurance training program, vasoconstriction (and the subsequent shunting of blood) to organs such as the liver, kidneys, stomach, and GI tract lessens. Thus allowing for a greater removal of cellular waste products, delaying the build up of lactic acid in the system. It is also theorized that the reduction of build up and stress in these areas lessens the activity of baroreceptors that trigger the sympathetic nervous system in regards to HR, BP, respiration, etc.
The studies were illustrated by training an athlete's 2 legs separately. When excercised, the better conditioned leg provoked less stress on the body (less sympathetic response) than the less conditioned leg, using the same testing criteria.
It's a very interesting study that is worth reading (if you're into that sort of thing). I have it in pdf form, but can't figure out how to upload it to the blog, so if you know how, contact me, and let me know!
