As a trainer, it is quite common to hear polarising expectations when people walk into the gym. On one hand you have “bro, I wanna get jacked” and on the other you have “I don’t wanna get buff and look like a freakshow”. In either case, people equate lifting weights to becoming a herculean demigod. This article talks what the what, when and how of muscle growth, and the various routes to destination Swoletown.
What is muscle growth?
Famous French bodybuilder Rene Descarbs once said “I trick, therefore I am”. This cryptic statement simply alludes to the gullibility of the human body. Should you ask your body to lift weights over and over again, it thinks it needs to get better at doing that in order to survive. One such adaptation is the increase in muscle size. Muscles are made up of several thousand fibres that are shaped like thin, long cylindrical columns. Given its shape, an increase in size can occur by an increase in its length and/or width, which ultimately increases its volume. This increase in muscle fibre volume is called hypertrophy.
What causes muscle growth?
If contracting a muscle is all it took to grow it, then all of us would walk around looking like swole doge. This suggests that not every contraction and weight lifted is going to trick the body into growing bigger muscles. While the body is gullible, it is also adaptable. Much like a con artist chasing ever-increasing stakes, you need to impose progressively harder stimuli to dupe the body into growing muscle; more like Robert De Niro in The Score and less like George Clooney in Ocean’s 11.
The reason we need a stimulus of sufficient magnitude is because muscles respond to effort. Think of effort as a regulator and not a switch. It has to be dialled up a couple of notches for the body to sense the need to adapt in size. In other words, the amount of effort detected by muscle fibres has to cross a certain threshold for the process of muscle growth to occur. Once this occurs, a cascade of chemical events follow that eventually leads to more protein being added to muscle tissue. This initial stimulus that muscles respond to is called mechanical tension and is the primary reason for muscle growth.
What happens when we exert effort?
The following flowchart is an attempt to illustrate how muscles respond to different types of effort.
Effort can be manifested in various ways and typically boils down to the force required to be produced. There are numerous ways in which a muscle might be called upon to produce force. If you read my previous article, remember that regardless of the way force is displayed, it is primarily affected by contraction speed. To understand why contraction speed plays such a key role and to help clarify the above flowchart, it helps to think of a muscle as an army of a thousand muscle fibres. In the face of any battle, a muscle has to answer two questions:
How many men (muscle fibres) does it need to send out?
How hard must each man work (force produced) to get the job done?
Let’s look at how muscles go about answering these questions, starting with slow contraction speeds. There are only three ways in which a muscle can work at slow speeds.
A light weight lifted with a deliberately slow tempo. Example - getting up from a chair at a snails pace. Since this is quite a simple and effortless task, the muscle decides that it’s not worth sending all of its men. However, the few that are sent out realise that gravity and inertia are a force to reckon with, and have to work quite hard to get the job done. Therefore, only the few good men that go to battle experience a challenging enough stimulus and adapt in size. To win the war on muscle growth, this isn’t a battle worth fighting. Grab something heavier.
The weight lifted is light-moderate and you’re fatigued. When you’re fatigued, lifting light weights no longer feels like a walk in the park. Lifting now requires a lot more effort and therefore a lot more men are called upon. As you know, an army has infantry and artillery divisions. In muscles, infantry is always sent first and the higher powered artillery follow. In this uphill battle, infantry is no match for fatigue and the artillery steps in to pick up the slack and get the job done. In this case quite a few men, if not all, have something to write home about and grow in size as a result of their valiant effort.
The weight lifted is extremely heavy. Example - lifting as much weight over your head as possible for one repetition. This battle requires maximum effort and therefore the entire army is put to test. Even the biggest and strongest men (artillery) are made to prove their worth. All muscle fibres experience significant mechanical tension and so adapt by increasing in size. While this might seem like the way to go, it doesn’t make sense to have all your men work as hard as they can all the time. This is a battle worth fighting once in a while.
In contrast, there is only one way in which a muscle can produce force at fast speeds, and that is if the external resistance (weight lifted) is light (since acceleration is inversely related to mass). However, the force produced is fairly high as force is directly related to acceleration. This means that even though the weight is light, a lot of effort goes into moving it. Example - throwing a ball, springing up from a chair, etc. In continuing with our muscle army analogy, this is less like a battle and more like an ambush against a hapless enemy. Even though every man is involved, each has little to do. Therefore, despite high enough forces, each individual muscle fibre isn’t made to sweat and doesn’t grow bigger as a result.
Conclusion:
Muscles discriminate between different kinds of effort based on contraction speed as this is what dictates how hard its divisions need to work. To ask a muscle to adapt, its stronger artillery has to be put to test. This is possible only if the weight is heavy enough to begin with or feels heavier than it is as a result of fatigue. Hypertrophy is one of the many adaptations to strength training, and up to a point, an extremely desirable one for everyone and every goal.