A lot of people focus on muscle groups they can actually see, says celeb personal trainer Monica Nelson . For example, people might focus on their quads but not their hamstrings, or on their arms but not their back , because they cant see those muscles when they look in the mirror.

While were not knocking on the chiseling power of routine squats and lunges -which mostly target your quadriceps and glutes-those techniques alone arent enough to significantly develop your hammies. And if youre constantly showering certain leg muscles with attention and forgetting to invite your hamstrings to the party, that could spell trouble.

The hamstring muscles are extraordinarily important in any activity that involves standing, walking or running , [as well as knee flexion and hip extension], says Janet Hamilton, C.S.C.S., exercise physiologist and lead running coach for Running Strong in Atlanta. If the hamstrings arent doing their job, someone else is going to have to chip in extra hard. These muscle imbalances can result in injuries [like knee damage, pulled hamstrings or lower-back pain].

Not to mention that your gams will look a heck of a lot better in your favorite mini-dress if theyre evenly toned in the front and back. Plus, if youre hoping to lift your booty, honing in on your hammies will surely help you get there. To find out how to get sleek and sexy hamstrings, we asked a handful of trainers for their go-to moves. These are the techniques they recommended that women add to their leg routine two to three times a week:

Dumbbell Goodmorning How to: Stand with your feet shoulder-width apart. Hold two dumbbells in your hands, bend your arms, and place them behind your shoulders. Keeping your knees slightly bent and your torso straight, slowly bend from your hips until your upper body is parallel to the floor. Hold for a moment, then return to start. That's one rep.