A: The muscle you’re referring to is the rectus femoris, and it is certainly true that unless you’re at single-digit bodyfat, you have little chance of seeing it—even if you’re flexing at full intensity.
That said, there are two exercises I have found to be particularly effective at targeting the rectus femoris, and doing them regularly will help to thicken it significantly. The first movement I recommend is the old-school sissy squats. They’re a much underutilized exercise, in my opinion, as they really add detail to the fronts of the thighs—and they’re anything but for sissies. Done correctly and with proper effort they can cause a searing burn in your quads that’s so painful, you may end up crying like a sissy. Here is a link to a Web page that shows you how to properly perform this movement: http://www.exrx.net/WeightExercises/Quadriceps/WTSissySquat.html.
A second exercise you can add is leg extensions performed with your feet pointed straight ahead, rather than flexed. To hit the rectus femoris even more intensely, put the seat back far enough that your torso is leaning back a bit.
Oh, and if you’re especially brave, try supersetting the two. Ouch!
Editor’s note: Eric Broser’s new DVD “Power/Rep Range/Shock Max-Mass Training System” is available at Home-Gym.com. His e-books, Power/Rep Range/Shock Workout and The FD/FS Mass-Shock Workout, which include complete printable workout templates and Q&A sections, are available at X-Workouts.com.