In other words, when fueled properly, the muscle that is subjected to overload in the form of very heavy weight, will first experience stress, then recover and finally grow. It adapts to the stress state and overcompensates to ready itself for future muscle stresses. Generally, the more fibers that are activated, the better the growth. During the process of progressive overload, there is a natural increase in the number and type of muscle fibers recruited. For example, light weights lifted for a large number of reps, recruit a majority of slow twitch muscle fibers which have a very minimal capacity to grow.
Heavy weights recruit both the slow twitch fibers and fast twitch fibers.
It is the fast twitch fibers that account for a majority of hypertrophy. As heavier weights are employed, the more fast twitch muscle fibers are recruited and the more the muscle grows. As you can see, the whole process is really very simple. The tricky part is understanding the best way to biomechanically achieve overcompensation, how to fuel the body properly to endure greater stress and how to fuel the muscle for optimal recovery. This is where your English magazines confuse the issues so terribly.