https://physoc.onlinelibrary.wiley.com/doi/10.1113/JP278455
We know that making muscles bigger (muscle hypertrophy) is volume dose dependent, meaning that the more exercise you do the larger your muscles will be. This research paper shows that the reason this happens is that as you exercise you have an increased amount of ribosomes in the cells of the muscle (ribosomal biogenies). Ribosomes are small cells that take RNA (lines of code created by one of the strands of DNA) and turn them in to actual proteins that can be added to the surrounding area. The more ribosomes you have the more proteins that can be made and so the bigger the "thing" will get. Therefore if you have increased ribosomes in the muscle there will be more protein synthesis in the muscle and that will cause the muscle to be bigger; muscle hypertrophy.
