Should you do aerobics or weight training to get a better shaped butt? Should you do both or emphasize on other? This depends really much on your goals, but if you are aiming to get a bigger butt the answer is quite clear. This depends of course on the current state of your body. Have you been eating really unhealthy life and have gathered a fat storage around the body. If the case is so the best option is then of course to emphasize on aerobics.
Cardio workouts and aerobics are mainly aimed to burn fat. Depending much on what aerobics you do, but in general your muscles will get more toned and maybe slightly bigger and you will lose that excess fat around your body. Aerobics will give you that slim, toned look. You have to exercise 3 – 4 times a week to get any real results with aerobics method. So if you are after bigger butt, the aerobics might not be your thing.
Then why is it important to get bigger butt muscles to get bigger butt? It is because, the bigger your butt muscles are the bigger your butt will be and look. Butt muscles in good condition will shape your behind to a rounder and bigger look. So the obvious answer to the question, aerobic or weightlifting is weightlifting. If you want to have bigger butt and bigger butt muscles you need to stimulate the muscles to grow and only really effective way to do it is by exercising your butt with weights. Aerobics or cardio exercising is something I recommend to do on the side. It will make your butt stand out more if your body fat percentage is lower.
So to get bigger butt you need to do different big butt exercises and perhaps some cardio exercising on the side.