What is the science behind building muscle? Here’s the quick overview:
Our muscle tissue is actually comprised of two different types of fiber; slow-twitch and fast-twitch. Slow-twitch fiber is all about endurance, as it is dense with blood vessels and able to carry a lot of oxygen. This makes this type of muscle ideal for distance runners, cyclists and other endurance athletes. Fast-twitch fiber is all about shorter, more concentrated bursts of energy and raw power, so it’s ideal for weightlifters, sprinters and other athletes requiring explosive strength. This fast-twitch fiber is also the type that actually grows.
How does this muscular growth occur? Simple. As you engage in some form of resistance training and overload your muscles, minute tears called microtrauma occur in the muscle fiber. Then, as the body sets out to repair the “damage” during your recovery time, the muscles in question actually grow back slightly bigger and stronger due either to an increase in muscle cells, or through a process called hypertrophy, which is the growth of existing muscle cells. This process is basically your body’s way of creating more muscle so that the risk of repeat “damage” is minimized. The tangible result is bigger, stronger muscles.
With this in mind, understand that each person’s total capacity for muscularity revolves to some degree around how these two types of fiber are distributed throughout their body. This is why some folks are naturally great marathon runners, destined to be lean for life (even if they take up weight training), while others are naturally great bodybuilders or strength athletes, seemingly able to grow muscle just by looking at a squat rack. In either case, anyone can reap benefits from resistance training with the right program.