Your gracilis is a long, slender muscle that runs down the inside of each thigh. It crosses from the lower end of your pelvis to the top of your tibia, the larger of the two bones in your lower leg. Because it crosses multiple joints, your gracilis performs multiple actions. It is primarily a hip adductor, but also assists with knee flexion. In order to stretch your gracilis, you must reverse both motions, straightening your knee and abducting your hips.
A standing stretch is ideal if you're not very flexible. Just spread your feet apart, legs straight, until you feel a stretch in your inner thighs. As you build flexibility, you can bend one knee, sinking into a side lunge to intensify the stretch on the other side. Spend an equal amount of time stretching both sides of your body. Avoid the temptation to sink all the way down into the side splits because it's hard to control your body weight in that position, and unless you're extremely flexible, you could end up hurting yourself.
For a somewhat easier-to-control gracilis stretch, sit down and spread your straight legs apart. Scoot your hips slowly forward until you feel tension in your inner thigh, then lean forward from the hips, keeping your back flat. With this stretch, it's important to remember to stretch to the point of tension, not pain, and to hold a static stretch instead of bouncing. Leaning slightly to one side intensifies the stretch on the other side of your body.
One of the easiest ways to stretch your gracilis is by lying on your back and scooting your butt as close as possible to a wall. Extend your legs straight up along the wall, then let gravity draw them down and apart. This is an ideal stretch if you're very flexible, but it might be painful and hard to control for the inflexible. You can use two exercise balls, one positioned beneath each leg, to help you control the stretch.
To get the most out of your gracilis stretches, follow basic best practices for stretching: Stretch after your muscles are already warm, either after your workout, after a few minutes of brisk cardio or after soaking in a hot bath; stay relaxed and breathe normally throughout the stretch; hold each stretch for 15 to 30 seconds, without bouncing; repeat each stretch three to five times per side; and try to stretch at least once or twice a week.
Your Other Hip Adductors
Not all of your hip adductors, or inner thigh muscles, cross the knee. The shorter adductor muscles might not stretch fully during straight-leg stretches, so consider doing bent-knee versions of the same exercises, like "butterfly" sits and squatting on your heels with your knees spread apart.