What is a “hip flexor”?
The term “hip flexor” is often used as if it describes one muscle, when in fact there are multiple muscles that do the job of hip flexion (bringing the knee towards the chest). Tightness in the front of the hips is a massively common complaint, and it’s much easier to address if you know which of your hip flexors are tight.
Like GI Joe said, knowing is half the battle…
This blog and video are a quick introduction to the 6 primary hip flexors, where they are, how they work, and how they affect your hip mobility. I’m not going to hide my un-secret agenda to promote better awareness of the iliopsoas (the deep hip flexors)!
The most important thing is to gain greater understanding of how your hips work so that you can work with them in a way that is optimal for your body.
So here are the main players in the hip flexor game:
The IlioPsoas (Psoas and Iliacus)
Let’s start with the big dogs… the Illiopsoas is a combo of the psoas and the iliacus. These are both hip flexors that attach to your upper inner thigh right in the groin area. They are your biggest, most effective hip flexors but they have some challenges.
The iliacus attaches to the upper inside of the back of the pelvic bone. The psoas attaches all along the inside of the lumbar spine. These attachment points are higher up on the body than any of the other hip flexors, giving these muscles better leverage to lift your leg, especially if you want it to go higher than your hip (hello dancers, aerialists, gymnasts, yogis and contortionists). Both of these muscles are deep in the body, making it hard to find them with your hands or brain.
Fun fact: the psoas is the only muscle that bridges the upper and lower body.
The psoas is affects and is affected by posture. If you sit a lot, or if you have an exaggerated bend in your lower back (check out the Bendy Back Tight Hips post) then your psoas can be chronically compressed into a scrunchy, tight, weak state where it is no longer effective either as a postural muscle or as a hip flexor. The illiacus right along with it!
Check out my upcoming series on core muscles and the psoas for some exercises and info to start to transform that predicament, if that sounds familiar to you.
In the meantime, let’s meet some more hip flexor friends.
This little guy attaches to the base of the pelvis and has a short journey down to the inside of the thigh bone. It is definitely an adductor (squeezes the legs together) as well as a hip flexor and you can see just by looking at it that it isn’t as big or as well-positioned as the iliopsoas for hip flexion. That wont stop it from trying to help out though, and if it gets over worked you can find yourself with some tight, grouchy inner thighs!
The Tensor Fasciae Latae (TFL)
This outer hip muscle is so important it got its own TFL blog post. This muscle attaches to the front outside of the pelvis and runs down the outer front hip, attaching to the famous IT band. Often tightness in the IT band can be traced back to a tight, overworked TFL. And it is easy to overwork the TFL because it can do so many different things: hip internal rotation, hip abduction (lifting the leg out to the side), and hip flexion. Like many competent beings, it can get stuck picking up the slack for under-performing friends.
A tight, weak, sad TFL can show up as outer hip pain, lower back pain, sciatica, and even knee and ankle pain.
The sartorius is one of the two hip flexors that crosses both the hip and the knee. This elegant, swooping muscle runs from the front outside of the pelvis down across the thigh to attach on the inside of the lower leg. That means it can help to straighten the knee, externally rotate the hip, and flex the hip. It is most effective at hip flexion when the leg is turned out, as in a ballet passé. In fact, this muscle is usually super strong on ballet dancers! It just isn’t as effective if you are trying to lift your leg straight out in front of you.
The Rectus Femoris
So many dancers, circus performers, and other athletes I have worked with over the years are very familiar with the rectus femoris. This is the biggest of your quadriceps muscles, crossing both the knee and the hip, right up the front of the leg. You can feel the big tendon in the front of the hip, just inside the hip bone, where this muscle attaches to the pelvis. Many people experience that tendon as being tight, tender, and possibly even inflamed due to overworking in the rectus femoris.
This muscle is the primary go-to for people who have difficulty accessing the illiopsoas, which can make the rectus femoris super cranky and tight. It can also create hypertrophy in that muscle so it gets really big and bulky (at the studio we fondly refer to that as femoris enormous or quadrisaurus rex). This is frequently an indication that the iliopsoas needs some love and encouragement.
Because the rectus femoris is both a knee extensor and a hip flexor, and because it attaches much lower on the body, it will never be as good at hip flexion as the iliopsoas. But it tries its best, bless its heart.
My hope in writing this article is that you now have a better sense of what is going on in your hips in order to tailor your workouts and your stretches to the muscles that need them most. If you suffer from chronically tight, painful hips and stretching isn’t helping, it’s likely due to an imbalance between these muscles where someone on the team isn’t pulling their weight, and other team members are having to play overtime and are getting resentful.
For the second half of the battle, check out the hip and core workouts on YouTube or the full length workouts on Video Club for some exercises and stretches that I have found useful to deal with hip challenges in both my own body and with my clients. I particularly recommend the next blog post on lunge variations to target specific hip flexors.
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