I am a former Assemblies of God pentecostal, and I can say that pentecostals believe very much in posture – although posture is left to personal discretion.
You stand when you worship – sitting would be disrespectful for whatever reason.
You raise your hands when you worship, if you feel comfortbale (though there is a high emphasis to do so). This posture can indicate many things: raising your heart to God, reaching out for God, lifting up your burdens to the Lord, and so on.
Kneeling/bowing. This is rarely – if ever – done in a pentecostal church. This is a pose reserved for those moments when you feel the spirit has led you to do so. It is the most holy and intimate places you can be. Generally, people on their knees have experienced the Holy Spirit in such a way that they are floored by it, or they are in such despair that all they can do is bend down and cry “Abba! Father!”
The only pose dictated is standing during worship. You don’t worship on your fanny! Everything else is left up to your discretion. There are variations as well. For example, you can raise one hand, both hands, place a hand on your heart, close your eyes, leave them open and so on. Each is welcome, and all are seen as a personal expression of worship.
I am actually very grateful for my experience as a pentecostal before becoming catholic. When you mix the “theology” of the poses in with the mass, it gives the mass a real “pop” as it were. You notice how we kneel during the most holy of times - the eucharist. First time I did so as a catholic I was near tears since being on my knees – as a former pentecostal – meant that I should have been so overwhelmed with God that I couldn’t stand, and indeed I was! I think this every time I go to mass now. I have even taken to sitting in the “cry room” or the very back of the church so I can raise my hands or close my eyes during the gloria or other hymns.