To fully stretch the rectus femoris, you must include hip extension (opening across the front of the hip) as well as knee flexion. The classic yoga pose that does this is Supta Virasana (Reclining Hero Pose). Unfortunately, many people with tight quads feel either knee pain or lower back pain—or both—in this pose. This can be due to poor alignment, so you might want to have an experienced teacher check your knee and back position and perhaps recommend props, like a bolster or folded blankets, to raise your torso higher than your knees. It's also a good idea to stretch the rectus femoris of each leg separately, because stretching them together can cause a strong forward pull on the pelvis, causing excessive lower back arching and pain. You can do this by practicing Ardha Supta Virasana (Half Reclining Hero Pose); place one leg in Virasana position while bending the other leg at the knee and placing the sole of the foot on the floor.
You can also stretch each rectus femoris separately in a modified version of Bhekasana (Frog Pose). Lie on your stomach and pull one heel toward your outer hip, using the hand on the same side so you don't pull your heel in toward your tailbone. Make sure to keep both knees within a few inches of each other, and keep the front of the hip on the stretching side on the floor. If the front of the hip comes off the floor, that hip is starting to flex, the rectus femoris is avoiding the stretch, and your lower back ends up overarching. To avoid all of these unwanted actions, make your tailbone heavy, press your pubic bone into the floor, and ground the front of your hip. Then gently pull the heel toward the outer buttock; visualize the quadriceps lengthening as you hold the stretch for a minute or more.
This pose can also serve as a check of quad flexibility: If your heel is several inches from your buttock, you have a lot of practice ahead to restore your full range of motion. But then, isn't that one reason we do yoga? Because it provides us with a lifetime practice in which we can work every day toward greater ease of movement, health, and freedom.
A licensed physical therapist and certified Iyengar Yoga teacher, Julie Gudmestad runs a private physical therapy practice and yoga studio in Portland, Oregon. She regrets that she cannot respond to inquiries requesting personal health advice.