Pulling exercises and correct body posture

I just want to know what is the propper posture to perform pull ups/chin ups. Its seems natural to me to arch a little my back but I dont know if its correct. Thanks

I'd say hollow. Upper back rounded, chest in versus chest out. This somewhat depends on what grip you're in. Not really the biggest deal and depends on what you are trying to do with it.

For pushups, we want a flat back if not rounded in shoulders. " Hollow. " We don't want the lumbar to sag.

Arching let's you recruit (well, rather emphasize) some more of the musculature in your back because you're fatiguing. This is similar in nature to arching during handstand pushups because it recruits more of the chest to help flex the humerus as the shoulders get tired.

Try to do them with a neutral body IMO.

I,ve been doing them in a swiss ladder to keep a hollow body and finded them waaay harder, also my abs skin dont like the swiss ladder too much Thanks both