Squats, lunges and how to build a butt out of nothing My butt is about the only part of my body that does not have an ounce of fat on it. I have been trying to build up the muscles but it does not appear to be working. What I think is happening is that I am using my thigh muscles for all the exercises. I am not asking for vanity reasons. It gets pretty darn uncomfortable to ride a bike or sit on a hard chair. There is very little padding back there. Is it possible to target those muscles without using the thigh muscles? My legs do NOT need to get any more muscle.