The hip flexors are the group of muscles that allow you to lift your knees toward your chest and bend forward from the hips. What is collectively referred to as the hip flexors is actually a group of muscles that includes the iliopsoas, the thigh muscles (rectus femoris, Sartorius and tensor fasciae latae), and the inner thigh muscles (adductor longus and brevis, pectineus and gracilis).
Starting in a seated position, place your bent right knee on top of your bent left knee. Try to have your knees perfectly stacked, one on top of the other, and to have your feet flexed to protect your knees. Both of your sit bones should be pressing into the ground. If this is not possible, then prop your hips up onto a blanket or pillow to allow equal and even weight on both sit bones.
Grade II (moderate): A larger tear in your muscle that makes it difficult to move and causes a moderate amount of pain, especially when you move the affected muscle, swelling, and tenderness. You may have 5 percent to 50 percent loss of function and you may be limping. You can't go back to sporting activities until the tear is completely healed. These injuries can take anywhere from a couple weeks to a few months to heal, depending on how bad they are.