Some people just don’t get it. Some people believe all kind of nonsense about muscle growth, and defend it with the religious zeal of a deranged preacher. For instance, many have it that you don’t grow without a pump – and train and train and train until they get one. (In fact, probably more people than not believe this.)
A pump is nothing but a temporary forced saturation of the muscles with blood due to extreme overwork. And, it’s perfectly possible to get a pump without fully fatiguing the fibres, anyway.
Yes – fatiguing the fibres is what it’s all about… as many of them as you can.
When you train, your time spent in the gym has one purpose only – to work as many of your muscles fibres to fatigue as possible. Each rep and set range coupled with the correct weight is designed to do this as optimally as possible. That’s all there is to it.
A fatigued muscle fibre is one which has been strained beyond its capabilities. A fatigued muscle fibre is therefore one which, by evolution, needs to grow in order to better complete the task next time around. You are basically signalling your body that you need a muscle mass upgrade to perform the task easier next time.
In the gym, basically, all you are trying to do is stimulate growth by fatigue. You are telling your body: ‘Look, this is what I have to do to survive, now help me out and grow.’ – Your body has no idea whether you are wrestling with a 300lb tiger and fighting for survival or you are purposely lifting weights in the comfort of your own home. And it doesn’t care – it has a task to perform, and it upgrades the machine to perform it better. It’s as simple as that.
…but, you’ve got to eat and rest. Stimulating the muscle is useless without having these other two components up to par.
Another factor is the different types of muscle fibres we have in our bodies. By using different rep and set ranges, with higher and lower weight, we can target slow twitch (endurance) and fast twitch (explosive) muscle fibres for more complete muscular fatigue – and inevitably, development.