Weight training. That’s right but people still don’t know why weight training stimulates muscle growth. We haven’t identified the signals or the substances that turn on muscle growth. Currently, there are two well researched theories that attempt to explain the process of muscle hypertrophy. The first is called the Muscle Damage Theory. This theory states that muscles are damaged during exercise and this damage turns on several signaling cascades that result in muscle hypertrophy (this appears to be the most widely and supported theory). This is the theory used by our model. The second theory is called the Substrate Accumulation Theory. The basis of this theory is that several substances accumulate during exercise that may turn on muscle hypertrophy directly or indirectly by stimulating the release of anabolic hormones.

Since the model assumes muscle damage theory, only it will be expanded (in other words, Substrate Accumulation Theory won’t be expanded).

Read more about muscle damage theory.