Now I have done benchpress 100 times  every day for 30 days. Progress has been great but I wonder how long should you rest your chest after benchpress 100 times a day for a month. 

@IsseG You should rest it for about 10 - 14 days! Did you take measurements before so you can take some after your rest days to see if there is a size difference?!

They became 1 inch wider. But can I still do chest exercisers in the 10 days?

@IsseG Damn nice man! You can, but it shouldn't be much. And not every day. I would stick to more accessory movements like maybe some flys here and there, but for the most part you want to rest your chest for a good amount of time before overloading it in any way

Can I train fullbody all the time or is it good for instance change to a push pull legs split to change things att the gym?

@IsseG You can change, but try to avoid changing things up often. I'd stick with one program for a good 6 - 8 weeks minimum before you look at changing. If you follow Full Body Evolution here for 12 weeks, you could then try the PPL program for 12 weeks after that!

https://muscularstrength.com/full-body-evolution

What do you I think I should do?

I have don fullbody for about 8 weeks now. I am thinking that I will do full body for an additional 4 weeks rhen switch to PPL. Will my muscles shrink now that I only train them 2 times a week?

Hey  man!

So if you have been training full body for 8 weeks straight I would do this.

1. Take a FULL 7 - 8 days off.  No lifting or maybe some cardio and abs.  I am not sure if you have been watching all my Nuclei Overload Videos, but "detraining" is the best way to try to spark muscle growth.  Then once the rest period is over you can go back to Full Body training if you want.  You don't need a totally new program (unless you want to try PPL to see if you like that better).

Either way, both programs offer multiple growth periods throughout the week so you can't go wrong!

But you said to train everything within 48 hours to maximize muscle growth so shouldn't it be every 48 hours with full body

Got it thanks, but can I do for instance 30-50 pushups each mornig and night just to keep the muscles stimulated

Even with PPL you're still hitting everything within 48 hours my friend. For example, you train PUSH on Monday, then again on Thursday. So you only have two days in-between before you smash it again!

If you wanted to do maybe some cardio and some abs that would be OK, but apart from that try to just have a rest week. Rest is important for growth as well!

I feel like I lost a little back lower back muscle so is it ok of I continue with full body but I add some back exersices

Yeah you can do that! If you want lower back specific movements, reverse hyper extensions or supermans could be good choices!