Muscles don’t grow evenly — some parts get bigger than others, and different muscles in the thigh respond differently to the same exercise.

Muscles don’t grow evenly—when you train your thigh, the top and middle parts of the front muscle grow more than the bottom, and the side muscle grows the same everywhere.

Different leg exercises make different parts of your thigh muscles bigger — leg extensions grow the front part, squats grow the lower outer part.

If you do leg extensions while leaning back, it might build more muscle in the top part of your front thigh compared to doing them upright.

Doing leg extensions with drop sets (going to failure, then lowering the weight and going again) makes the front part of your thigh muscle bigger in the upper and middle areas, but not the bottom part or the side muscle.

If you want to grow the front part of your thigh muscle (rectus femoris), doing leg extensions might work better than doing leg presses.