Originally Posted by Richard Cranium
If I was going to make wise cracks about where and how muscle-mass is gained or lost - I'd point to the nature of blood vessels surrounding the fibers and the tremendous changes in volume that blood and glycogen produce. Too bad no pictures can depict this "swelling" and shrinking of a muscle produced by these factors, I'm sure they count for something. In this pic, glycogen doesn't look like it is taking up much space........
I agree that swelling due to any factor be it water, glycogen, fat droplets etc may effect measured mitochondrial function in that the distance fuel and waste must diffuse will be increased with swelling. We know that the degree of capillarization is one of the most important factors determining exercise performance and fatigue resistance. So losing a small amount of contractile protein may increase mitochondrial function just by the fact that the mitochondria and capillaries are closer together.
Fortunately, that study not only measured total mitochondrial function but also mitochondrial gene expression/concentration. They concluded that the mitochondrial mtDNA did not change significantly (up or down); suggesting that the mitochondria were basically “ignorant” to any whole muscle changes occurring and that functional improvement was likely due to what I mentioned above.
“Also, muscle mtDNA content did not change significantly [1665 (213) vs. 1874 (214) mtDNA/nuclear DNA], denoting functional improvement rather than proliferation of mitochondria as the principal mechanism of enhanced ETC activity.”
I am by no means saying I have all the answers and would love to hear others opinions on this very interesting subject. Could muscle mass “cycling” be a way to increase mitochondrial density?
For example if I gain a large amount of muscle mass, followed by endurance training and hypocaloric wasting will that lead to a greater MT density than just endurance training a “small” muscle? Assume that in the final state both the “cycled muscle” and the “always small” muscle are the same size. Discuss.