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).
Before discussing different strength and mobility exercises, we should first look at activation exercises for your Gluteus Maximus (referred to as the glutes) muscles. The reason for needing to activate your glutes is simple—as a population, we spend way too much time sitting, and as a result, what happens is what noted spinal researcher Stuart McGill terms gluteal amnesia—your glute muscles can "go to sleep" and not function properly.
Loop a resistance band either above your knees (least resistance), below your knees (medium resistance), or around your ankles (greatest resistance). Bend knees slightly with your feet hip-width apart. Step to the side until the band provides resistance, then slide your other foot over to re-create your original stance. Repeat this sidestepping movement for 10 to 15 feet in one direction (or as far as you can), and then cover the same distance in the other direction.
Your hip flexors and psoas muscles help drive your legs up when you are running. To stretch these muscles, kneel on the floor and then step out forward with your left leg so that your left foot is on the floor. With your back straight, lean forward so that your weight is on the front foot and you feel a stretch in the hip of the back leg. Perform the stretch on both sides.
Sacroiliitis is an inflammation of one or both of the sacroiliac joints, the spot where the lower spine connects to the pelvis. Sacroiliitis can cause pain in the buttocks, lower back, and may even extend down one or both legs. The pain can worsen with prolonged standing or climbing stairs. Sacroiliitis can be caused by arthritis, injury, pregnancy, or infection.
How to do it: Put a 20- to 36-inch box behind you. With your feet hip-width apart, lift your leg and place the instep of your rear foot on the bench. Lower your hips toward the floor so your rear knee comes close to the floor, keeping your back straight. As you descend, make sure you don’t bend the torso excessively forward and your front knee does not pass your front toes. Pause when your rear knee is close to the floor and your front quad is parallel with the floor, then drive through your front heel to return to the start position. Repeat this movement, alternating sides each time.
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.