The iliopsoas muscle (pronounced with the "p" silent) is made of three muscles: the iliacus, psoas major and psoas minor. Together these muscles work to flex the hip, rotate the hip outward, bend the spine laterally, and stabilize the spine. These muscles have deep attachments at the torso, with the iliacus attaching on the front of the pelvic bone, and the psoas muscles attaching on the front of the spine, and they attach to the front of the femur just below the hip joint.
Types of Exercises
The iliopsoas muscles could be exercised either in isolation or in multi-joint exercises. Isolation exercises are those that challenge the muscles in their primary action only, in this case hip flexion, with no other joint movements occurring. Multi-joint exercises are those where movement is occurring at more than one joint simultaneously. Multi-joint exercises tend to be more similar to real-life movements than isolation exercises. Your selection of exercises may depend on muscle strength and balance of the iliopsoas and other muscles that attach to the pelvis.
Performing a leg lift is a simple way to isolate the hip flexors. Lie down on the floor with arms at your sides and legs straight. Lift your right leg until the hip is at a 90-degree angle, slowly lower down to the starting position. If more than 15 repetitions can be completed easily, weight may be added with an ankle weight. This exercise can also be progressed by performing the same movement in a standing position. Stand on your right foot, use a bar or wall for balance if necessary. Hold the left leg straight and lift as high as you can while maintaining tall posture, slowly lower back to the starting position. Perform an equal number of repetitions on both sides.
A multi-joint exercises that challenges the iliopsoas muscle is the side plank. Lie on your side with your elbow on the floor directly under your shoulder and both knees bent to 90 degrees. Lift your hips off the floor until your body is straight from your shoulders to you knees. Slowly lower your hips down to lightly touch the floor and lift back up. When 15 repetitions can be easily performed, progress to performing the exercise with the top leg straight, then to both legs straight. To target the hip flexors more, slightly rotate the front of your body towards the ground. Be sure to complete the same number of repetitions on each side.
Spinal Stability Function of the Iliopsoas
Because the iliopsoas attaches to the spine, pelvis, and femur, it will function to cause movement or stabilize of all of these bones. For this reason, many exercises such as full situps, all types of leg lifts, plank and side plank, and lateral spinal flexion rely heavily on the strength of the iliopsoas as well as abdominal muscles. The benefit to this is many muscles may be trained simultaneously in a few multi-joint exercises. The downside is that occasionally, stronger muscles dominate over weaker ones which leads to even greater imbalance. It is important to be conscious of the muscles you are attempting to train in a particular exercise and be sure those are the ones you feel doing the most work.