The first reason that rest is so important is that that is when your muscle actually grows. When you are training in the gym, what you are actually doing is tearing your muscle fibre, that is to say that the neurons in your arms are actually being ripped in half in what are called micro tears. Returning to train these muscles in this state then would mean you were relatively ineffective, and would mean you actually made yourself less likely to grow as you kept doing damage. What you need to do instead then is to rest the muscles so that they have a chance of recovering and building themselves back up to full size meaning you could eventually do permanent damage. And of course the harder you push your muscles, the more you need to rest them. This is why professional bodybuilders and serious amateurs will not train their whole body in a single session, but will instead train each body part on a set day of the week. This way each body part can have an entire session to work it meaning it is trained as hard as possible – but that it then has a whole week to recover. If you train this way you can also avoid training every day of the week and make do with just four days or five days. Stallone to be in the shape he was in for Expendables or Rambo still didn't train every day of the week, but instead allows himself the time he needed to recover.
Another technique some bodybuilders use is to take a whole week off every couple of months. This is something they do in order to shock their body out of a plateau, but also to give their muscle and their body a chance to recover. While not every bodybuilder does it, many swear by it, and you will find that if you take a week off of your training you tend to actually grow rather than slimming down as you might expect.
Taking rests like this also helps to prevent something that every bodybuilder fears – overtraining. This is something that is very much how it sounds, and describes occasions when you train yourself too much and end up tired and achy and with many of the symptoms of a flu. This happens simply because you have pushed yourself too hard and it will result in your inability to train as much as you should be subsequently as you have to wait for your body to recover before you can put effort back into your workouts. In this sense taking time out is an investment as it allows you to put more time in the rest of time.
Sleep is also important when you are bodybuilding as it is your most 'anabolic' state. An anabolic state is any point in which you are building muscle rather than burning it, and when you are repairing wounds etc. This is seemingly one of the main purposes of sleep – to heal and recover after the day's events, and during this stage your body produces large amounts of growth hormone, which cause your body to burn fat, build muscle, heal wounds and generally make repairs and alterations – which is of course crucial after you have done a workout. Lots of healthy sleep will also give you the energy you need to be able to put lots of zest into your workouts.
There are ways that you can make your resting periods more effective, for example by eating lots of protein and amino acids, as this is what your body will use to make its repairs. Similarly you can increase your growth hormone with supplements such as GABBA or with hot baths, and naturally with hot showers. In short though any type of rest will help and it is time to stop thinking of it as slacking off, and instead as a crucial technique for improving in size and definition.
