There's OT and NT examples of folks falling prostrate in intense spiritual/heavy Holy Spirit situations.
A service I was in as a teen . . . less than 2 feet from me, a woman was prayed for--lightly touched on the forehead--if that--may have fallen before actually being touched--and her body, including head bounced off the hardwood floor at least an inch or 2. I was shocked and thought at the time--she's gonna have a goose egg on her head and some headache.
After lying there a while worshipping God, she got up none the worse for wear in any respects.
I almost tipped over from the heaviness of the Holy Spirit this weekend at a seminar at our church. I didn't but someone was behind me in case I did. It was a powerful time of prayer for me. People who don't understand what's going on are always critical of what God's trying to do in these end times. Sigh.