Answer:
Muscles are not a simple unit. Each muscle is formed by a series of fibers, each of which within its own fascicle, and each innervated by the terminal of a skeletal muscle neuron.
Whenever movement, or force, needs to be exerted by an entire muscle, these fibers, classified now as Type I (slow-twitch fibers) and Type II (A and B) (fast-twitching fibers) will get stimulated by the terminal end of the neuron depending on the purpose, and will initiate contraction.
In the process of muscle activation, it is important to know that essentially slow-twitching fibers (Type I) are the first to be recruited in movement, but they are not the best at fast action and much less at carrying heavy loads.
However, whenever we talk about the correct steps of recruitment, we need to know that stimulation will first be of slow-twitching fibers, who will initiate the process of contraction first, and as the need for more fibers increases, and the load, or speed of movement increases, then Type II A and B fibers will also be stimulated to initiate contraction as well. Today, research has shown, however, that there are instances in which stimulation may be selective of one type of fiber only, depending on the need.
Given what was said before, we can then say the following about the statement: Although it is true that slow-twitching fibers are not able to respond very fast to stimulation, and cannot generate much force, they are the first ones to be recruited, as the correct steps are slow-twitch fiber recruitment and then fast-twitch fiber recruitment if the load and speed require such. Sometimes only the slow-twitch fibers will be recruited, if the load, or the speed required from the muscle, does not exceed a certain level.
