Have you ever heard of Golgi apparatus? Well, it is the thing in your cells that is responsible for estimating how much stress it can take (roughly speaking).

Have you ever heard of Golgi apparatus? Well, it is the thing in your cells that is responsible for estimating how much stress it can take (roughly speaking). Human strength is limited not by the muscles but by the tendons and nerve signals. Here is an explanation. When you try to lift something your body knows instantly whether it is able to do it or not. If you do not believe me, go try and deadlift an impossible weight. As soon as you start lifting it after setting up, your body will relax and will not let you. It is a protective mechanism. Now, it the weight is close to what you can handle it will let you fight the weight and attempt the lift. Similarly, there are many occurrences where a mother will lift (with ease) concrete blocks of several hundred kilograms to save herself and her child. Perhaps the more famous one was of a man who was stuck under a huge boulder after an accident in the mountains. As far as I recall, the boulder was about 600kg. He threw it off with ease. You know what happened with him? He tore every single muscle off his bones while doing that. I am giving these examples to illustrate why such protective mechanisms exist. If they did not, we would be tearing muscles off bones daily. Now, when it comes to powerlifters, they use low repetition and high weight precisely to increase the limits of their tendons and the power of their nerve pulses. In addition they are working the creatine-phosphate (ATF) energy capacity of their body that is responsible for very short-term work. This has nothing to do with protein. I assure you that any person is physically capable (speaking of muscles) to lift huge weights. It is just that your body will not let you. When it comes to bodybuilders, they train their strength (tendons and bones) as well, but as a side-effect to trying to bloat their muscles.