the body during flashbacks

wondering if anyone knows if this is a normal experience/has had something similar occur- when i have physical or extreme flashbacks, my body always moves to the same position i was in during the event, and certain body parts feel unable to move. my arms and hands feel weighed down and frozen, where even if i try to move them, i'm not able to. my legs move to a certain position and either feel frozen or i feel as though i'm not "allowed" to move them, so even if i physically can, i'm not able to for that reason. i have heard about other people freezing up, but never about the body mirroring the same position it was in during assault- is this all in my head?