"Hip flexor" is one of those terms that has kind of lost its meaning. Most of us know that our hip flexor is a group of muscles that allow us to lift our knees and flex our hips to bend at the waist. Found deep in the abdominal cavity, they are some of the strongest muscles in the body. Where things get confused is the actual anatomy of the hip flexors, which influences the hip flexor strengthening exercises we recommend for athletes.
The hip flexors are comprised of five muscles: the tensor fascia latae, the rectus femoris (often only associated with the quads), the iliacus, the sartorius and the psoas.
Ideally, we would stop referring to them as the hip flexors and speak only about the individual muscles. But this probably isn't going to happen, unless you're taking an anatomy class and don't mind people giving you funny looks when you mention one of these strange sounding muscles.
Deficiencies in the hip flexor group are most typically found in the psoas and illiacus—often referred to as the iliopsoas. This is especially true if you cannot hold your hip in a flexed position above 90 degrees while maintaining proper posture. The psoas and iliacus are the only two flexors that assist this degree of flexion. When you lack strength in them, you have to compensate, which is usually done by loading the lower back or the other three flexors. This makes a weak iliopsoas a prime suspect for low-back pain, strains or a poorly aligned pelvis.
Understanding the differences among the hip flexor five muscles can help you prevent or alleviate back pain and strains in the flexors and quads. It can also help determine the type of hip flexor strengthening exercises you need in your program.
You can see how important this is for athletic performance, because low back pain and strains are serious problems. Let's discuss the differences among the five muscles.
Knee to Chest & Release
This is a way to assess strength in the psoas and iliacus, to determine whether an athlete passes or fails the test of strength in this area. Stand in a normal stance with your feet under your hips. Flex your hip and wrap your hands around one knee, pulling it all the way up to your chest, then release your leg. The goal is to hold your knee above 90 degrees with no hands, using only the strength of your psoas and iliacus.
A couple things indicate failing the test: any type of leaning or tilt in the back or pelvis; and feeling cramping or tightness in the hip area. Sometimes when an athlete releases his or her knee, it drops straight back down to ninety degrees and locks up. Check the video below for a demonstration of the test. You be the judge. Pass? Or Fail?
Strengthening A Weak Hip Flexor Group
When strengthening the hip flexors, application becomes very simple. There is nothing pretty or flashy about the exercises that strengthen this muscle group.
I like this exercise for a couple reasons: it confers additional benefits by working your lower abdominals; and it can be loaded with extra resistance via a med ball or a weight plate. I'm sure everyone is familiar with this exercise. Using a decline bench, keep your back straight while you sit all the way up and then lower back down slowly.
This is a another simple exercise, which is typically used as part of dynamic flexibility warm-up or for hip mobility. Again, I like it because you get more bang for your buck. You get a deep stretch in the flexors, and if you perform it correctly, you also reap benefits in the glutes. Start standing straight up with your feet together. Take a lunge step forward and drop the same-side arm down. Try to place your elbow inside your foot, as close to the ground as possible, without your back knee touching the ground.