Hip Flexors vs Ab Muscles - How to Balance Them?

Are Your Hip Flexors Taking Over Your Ab Exercises?

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If you take Pilates classes or fitness class you might hear the phrase, "stay out of your hip flexors." What does that mean? And can you do it?

What Are the Hip Flexors and What Do They Do?

The hip flexors are a group of muscles that bring the thigh and trunk of the body closer together. You use your hip flexors in many daily activities like walking, stepping up, and bending over.

Technically, the hip flexors are the illiacus, psoas major, pectineus, rectus femoris, and sartorius muscles.

Obviously, we need our hip flexors. But we usually don't need them as much as we use them in ab exercises.

Hip Flexors Take Over Ab Workouts If You're Not Careful

Here is the problem: When we exercise to target the abs, as we do in Pilates, we do exercises that decrease the distance between our thigh and trunk - think sit ups, roll-up, leg lifts. The hip flexors are a strong group of muscles, and they try to take over. We end up working our hip flexors more than our abdominal muscles! This is one of the ways that you can do 500 sit ups and not have a single one of them truly target your abs.

You know the kind of sit ups where you put your feet under something that holds them down and do a whole bunch of sit ups with an almost flat back? Guess what? Mostly hip flexors. Pilates people run the same risk with the many flexions (forward bending) exercises we do.

How do I Get Out of my Hip Flexors?

The answer isn't simple.

A lot of us have to work on the hip flexor habit constantly. For one thing, you can't really leave the hip flexors entirely out of most ab exercises. They are still an important part of the picture. The idea is to get the abs involved as much as you can and to keep the hip flexors from taking over.

Our first line of defense is always awareness. When you do Pilates or other ab focused work, put your attention on your abdominal muscles. Start to figure out for yourself what feels like abs and what feels like hip flexors. It might help to familiarize yourself with the abdominal muscles and their functions. Work also with being aware of how over tucking the pelvis can bring the hip flexors into play.

Trouble Signs for Strong Hip Flexors and Weak Abs

Low back pain and soreness in the groin area may be signs that you are weak in the abs and over-using your hip flexors. Another clue is not being able to keep your feet and legs down when you do a sit up or roll up. Do you see the logic in that one? What's happening there is that the abs aren't strong enough to do their up-and-over contraction, but we've told the body to get the trunk and thigh closer together, so the hip flexors take over, and the feet fly up. (Tight hamstrings play a role too)

The other side of hip flexion is hip extension.

It is important to have the muscles of hip flexion and hip extension work together in a balanced way, and many of us have weak hip extensors. That discussion is in this article: The Basics of Hip extension.

4 Pilates Exercises to Increase Awareness and Balance Ab and Hip Flexor Use

These basic Pilates exercises can help increase awareness and set the foundation for abdominal strength and body mechanics that balance ab and hip flexor use:

  • Knee Folds: In knee folds, we use the abdominal muscles to stabilize the pelvis so that we can feel the subtleties of the hip flexors at work. In knee folds, we also try to keep our big muscles, like the quadriceps of the thigh, out of the exercise as much as possible.
  • Chest Lift: Chest lift engages all the abs, but it feels more like an upper ab exercise. In it, we stabilize the pelvis in a neutral position and move just the upper body in isolation. Your hips and legs should stay still and do not grip. If the hip flexors start to get over-involved, you might have a sense that your knees want to pull toward your chest, or tightness in the groin and thigh.
  • Supported Roll Back: This exercise invites a deep abdominal scoop. Right, there you feel those abs. As you begin to roll back, You might sense a point where the hip flexors want to grab the movement. You can feel that at the crease of your thigh. As you roll down, the hip flexors will have to do some stabilizing, but try to maintain a focus on rolling down and controlling with the abs. Thinking of getting some space between the top of the thigh and the lower abs can help.
  • The Hundred Modified: The full hundred calls for the legs to be extended. The hip flexors often see that as a call to over-action. Work with the hundred in a modified position with your knees bent and feet flat on the floor, or legs in table top. That way you can focus on using the abdominals.

As you work on increasing your awareness of the relationship between the abs and the hip flexors, you will discover that there is reciprocity in terms of one set of muscles doing the stabilizing of the trunk or pelvis while the other set moves. What we want to achieve is muscular balance, better functionality, and ultimately more choices about how we move.

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