The Science Behind Muscle Growth
Building muscle is hard, but one key principle can change everything
Humans have never been particularly muscular. We survived periods of scarcity because our genome allows us to catabolize unused muscle, thus reducing our caloric requirements. Our virtue has always been endurance rather than raw strength.
Nowadays, however, there is an increasing appreciation for more musculature bodies. We have gyms, bodybuilding competitions, social media influencers flexing their muscles and showing off their abs, extremely fit and athletic movie stars… I mean, what guy wouldn’t want Zack Efron’s physique in Baywatch? The image of muscular and athletic frames is spread all across the world. Men desire a big chest and arms just as women desire big glutes and legs.
However, building muscle is an extremely long and strenuous journey for most people. You can’t just sit in your desk all day and expect your muscles to magically grow. Besides, most people have no clue about the biological mechanisms behind muscle growth. Don’t get me wrong, you don’t need a PhD in biochemistry in order to develop your muscles, but some knowledge in the subject will most likely benefit you.
There are no magic pills, but perhaps this post might help you achieve your dream physique.
Common misconceptions:
A common idea is that muscle grows as a consequence of muscle damage. At first glance, it does make sense. The muscle gets damaged and the body repairs it, causing it to grow.
However, scientific research has shown that muscle damage doesn’t correlate with muscle growth. It is just an unavoidable collateral effect of resistance training.
No pain, no gain. This motto echoes through the walls of every gym.
First, if you feel pain doing an exercise, stop it. Risking an injury is never worth it.
Yes, it is important to train hard. You will never stimulate your muscles to grow if you don’t put enough effort into the workout. However, working out like a maniac isn’t beneficial to you either. To much muscle damage can actually be detrimental to muscle growth since it will take you longer to recover. Longer recovery time means that instead of working out that muscle twice a week you will only be able to work it once, which then translates to less gains. Bottom line is, if you lost the ability to use or feel a muscle after working out, you probably over-did it. Muscle soreness doesn’t translate to growth, it’s just a clue that you worked that muscle.
Another incorrect belief is that muscle grows primarily due to metabolic stress, such as the accumulation of lactic acid during exercise. Again, this is incorrect. Marathoners drown in lactic acid every time they run, yet their muscles aren't very developed. One could argue that lactic acid triggers some growth response, which might be optimal for muscle growth. Nonetheless, it has been proved that metabolic stress is not the primary cause of muscle growth.
Mechanical tension is king:
Muscle fibers grow as an adaptation to stress, a stimulus. This stimulus is mechanical tension.
You already know that our body evolved to survive. For that reason, it will always try to save the fast-twitch fibers, a more powerful and energy-demanding type of muscle fiber, exclusively to when they are strictly necessary. The body tries to avoid superfluous expenditures of energy at all costs. This is where mechanical tension becomes important. More tension across the muscle will force the body to recruit more muscle fibers, especially the fast-twitch ones. That's why you should always train legs. Walking and running don't bring enough intensity to the game. Hence, the body only engages the slow-twitch fibers, which yield very little growth potential.
Now, with mechanical tension in our mind, we are now able to plan our workouts in order to effectively build muscle over the long run. We have to do it in a way so that we can progressively increase the tension placed in our muscles. This is called progressive overload. Progressive overload implies that you keep gradually increasing the stress placed upon the muscles.
You can do it by increasing the weight, by choosing a different exercise or by developing a better mind-muscle connection with a certain muscle, which will allow you to recruit more of its fibers.
There are a plethora of ways to achieve progressive overload, but it is extremely important that you do so.
A biochemical view:
Muscle growth is decided by the balance between muscle protein synthesis and muscle protein breakdown. In order to grow muscle tissue, we must increase muscle protein synthesis.
During resistance training, when the muscle contracts under a tension, there are two processes occurring. The body will block the inhibition of a molecule called Rheb, which in turn will activate another molecule, mTOR. At the same time, a lipid molecule called phosphatidic acid (PA) will also activate mTOR by binding to it.
The molecule mTOR is a protein kinase that regulates protein synthesis. Being highly anabolic, the mTOR will then stimulate protein synthesis and cellular growth.
Such molecule is activated by amino acid intake (especially leucine), growth factors, such as insulin and growth hormone, and anabolic steroids. However, it is also highly activated by the eccentric part of an exercise under heavy weight. For instance, when lowering the dumbbell during a bicep curl. Again, mechanical tension.
How you can apply it:
We have already established that in order to continuously build muscle one must follow the principle of progressive overload. However, being familiar with the concept isn’t enough. You must know how to apply it to your own workouts. That’s the issue I’ll tackle now.
Whether you lift weights or you work with your own body weight, your objective is to keep increasing the tension placed on the muscles.
Let’s first imagine an ordinary person going to the gym. I will assume it’s a man, although the procedure remains the same regardless of the person’s gender. He has been following a workout plan for sometime and is now comfortable with it. The problem is, if he keeps doing the same workout week after week without changing it, he will stop building new muscle. Why? Because his body has already adapted to that stress, having no need to grow new energy-demanding muscle tissue. The body will only build muscle if it has no other option. The solution? Increase the mechanical tension. The easiest way is to just lift heavier weights. Lifting gradually heavier weights will allow you to increase both muscle mass and strength. Other options include increasing the training volume ( doing more sets and reps or going one extra day to the gym) and upgrading your exercise selection. If you want to build your chest, choosing an exercise that provides higher chest activation is obviously a good choice.
But maybe you prefer working out with only your body weight. If that’s the case, you might have to adopt a different strategy. Since your body weight stays nearly the same, your best option is to do harder progressions of one exercise. For example, you can progress from regular push-ups to declined push-ups and then to archer push-ups. Squats can turn into Bulgarian split squats and into pistol squats. Unilateral training is going to help you tremendously if you only do body weight exercises. When you become comfortable with an exercise you must always think of ways to make that exercise harder. Your goal is to increase the stress placed on your muscles. That’s why doing 200 push-ups a day for a month doesn’t work, it’s too easy for your body to adapt. You will never grow if everything stays constant, you need change.
Wrap-Up
The main conclusion that you can take from me is that, in order to keep growing your muscles, you need to gradually increase the tension exerted on them, assuming you are not starving yourself of energy or protein.
If you are relatively healthy, your main concern must be mechanical tension and progressive overload. Forget all the others minor details.
