I have trained with a good amount of bodybuilders like I think like a yard train with them and one of the things that they really said to was always squeeze and use your heels when you're really focused on the glutes so whenever you feel some glutes really use your heels a lot and then if you're doing a machine you have to squeeze and make sure that like your body is like on your body but your glutes are mainly the ones holding the weight and not any other part of your Body