These are dense knots that form help to make it a hardship on the muscle to raise your energy. Is usually also possible to injure hip and gluteal muscles, in particular when you fall on your bottom. https://evernote.com/shard/s499/sh/745c682d-c710-f5a1-c9a4-070ed871d7cf/GmxK7PeCtCl7-0qF7nHHhMCZGkv26EmELvFgH2VjZFW4rTtCRFF91Ys2Ng