When you train your quads, the big front muscle (rectus femoris) grows more than the side muscles (vastii), even when you do the same total amount of work.

After resistance training, the thickening of the vastus lateralis muscle in young men is not the same along its length: the part closer to the knee grows more than the part closer to the hip.

When performing resistance training, training to muscle failure may lead to slightly more growth in the vastus lateralis muscle, while training with 1-2 reps left in reserve may lead to slightly more growth in the rectus femoris muscle.

If you're a guy who's already lifting weights, doing 4 workouts a week for 8 weeks will noticeably grow your thigh muscles — and it doesn’t matter whether you stick to the same routine or mix it up every time.

This study only looked at the front and side of the thigh—so we don’t know if doing more sets helps your front thigh or hamstrings grow more.

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.