When referring to AAS, we commonly use the term testosterone and testosterone derivatives. Testosterone is the basis of all AAS and is also a kind of AAS. So how does testosterone build muscle?
The most common understanding of how testosterone stimulates muscle growth is that it activates and increases the number of muscle fiber precursor cells. Muscle fiber progenitor cells also call satellite cells. Once activated, these precursors may blend into existing muscle fibers, making them larger, or satellite cells may fuse together to form new muscle fibers.
In addition to activating and increasing satellite cells, testosterone also increases the number of muscle nuclei and thus the number of available androgen receptors to which testosterone can bind in muscle. When combined with training, which increases the sensitivity of androgen receptors and depletes amino acids necessary to support protein synthesis, testosterone has an increased impact on muscle and performance.
Testosterone is also anti-catabolic because it blocks the ability of catabolic hormones, such as cortisol, to bind to their main receptors.
Therefore, testosterone is both an anabolic and anticatabolic steroid that builds and maintains muscle mass and helps with rapid recovery after exercise.
Testosterone has also been shown to increase the energy of muscle contractions by increasing the amount of calcium released within cells, thus providing strength gains and explosive power during training.
Testosterone also stimulates red blood cell development. More red blood cells in the blood give the muscles better oxygen-carrying capacity, which improves endurance during training and helps bodybuilder train for longer.
In addition to gaining muscle mass, Bodybuilder also helps boost endogenous testosterone levels.
Testosterone is the most basic AAS. Synthetic AAS are derive from testosterone and have similar anabolic and anticatabolic effects as testosterone, and they stimulate muscle growth in the same way.