The iliacus muscle is often grouped in with the psoas major muscle and called the iliopsoas. The Sports Injury Clinic notes that the muscle is located on the outside of the hip and it is responsible for hip flexion, hip rotation and flexing the torso. A few different stretches are available to work the iliacus muscle.
Kneeling Hip Flexor
The Sports Injury Clinic notes that the kneeling hip flexor stretch is a common and effective move used to stretch the muscles at the front of the hip. Kneel on the floor, step one foot forward, knee bent at a 90-degree angle. Curl the toes of the back leg under and square your hips to feel the stretch in the back-leg hip. Hold the stretch for at least 15 seconds and then switch legs and repeat.
Butterfly, No Bouncing
Sit on the ground, imagining a string pulling you straight up from your tailbone to the crown of your head. Bend both knees and bring the soles of your feet together. Grasp your feet with both hands and rest your elbows on your knees, hinging forward slightly at the hips. Gradually press down on your knees with your elbows to feel the stretch in your hips. Hold the pose for 15 to 30 seconds without bouncing your knees. Repeat butterfly three times.
Lying Hip Stretch
Lie on your back, knees bent and feet flat on the floor. Cross your right ankle over your left knee so the inside of your right ankle is facing you. Then pull your left leg to your chest with both hands under your thigh to feel the stretch in the hip of the right, crossed leg. Hold for at least 15 seconds and then repeat with the left leg crossed over the right knee.
Standing Hip Flexor
The standing hip flexor stretch is a dynamic stretch -- a motion exercise that can be used as part of a warm-up. Start by placing one foot on a low step or platform approximately the length of your leg in front of you. Your front knee should be flexed at about 90 degrees. Lunge forward slowly, keeping the heel of the back, extended leg on the floor. Keep your chest high, torso upright and hips square to feel the stretch in the hip of the extended leg. Hold the stretch for 15 to 30 seconds and then change legs.