Why hip flexion isn’t bad (and why stretching isn’t always the answer)

Currently, the fitness industry is on a mission against hip flexion. A quick google search links tight hip flexors to 492,000 hits on squat and hip dysfunction, the best stretches for tight, sore hip flexors, and how stretching your hamstrings and hip flexors will fix your low back pain. (Really? I thought we had moved past the whole “tight hamstrings cause low back pain” statement, but it appears I am mistaken). On the second page, I did find an article on bodybuilding.com titled, “Flex those Flexors,” giving me hope that maybe a few of us are recognizing sitting isn’t make our hip flexors, “tight and weak” like we originally thought. (A search on yoga and hip flexors revealed a similar trend of stretching. However, Yoga Journal offered a pretty good article on how to “lengthen and strengthen your hip flexors.” Suggested poses included boat pose, an isometric hold in a V position, bridge, a hip extension hold, and crow, an arm balance involving deep hip flexion. I was actually impressed by the lack of backbends disguised as lunges).

If we are thinking purely from a sagittal plane perspective, there are two common ways to flex the hip with a bent knee: lift the foot off the floor or squat down. Lifting the knee up flexes the hip in an open chained manner; squatting is a close chained exercise. Both require strength and both have different compensations. Today, we will focus on the action of the lifting the foot up.

Lifting the foot can either be done with a bent knee or a straight leg. For the purpose of this blog, we are going to focus on lifting the foot with a bent knee. Most general population clients will struggle with this movement at first. Keeping the leg straight and lifting the foot feels more challenging. (If you don’t trust me, stand up and try it. Which feels like more work?).

There are several muscles involved in bent knee hip flexion, including the psoas major iliacus, sartorious, tensor fasciae latae, adductors, pectineus, and gracilis (Clippinger, 2006). When you read through this list of muscles, hopefully you recognize most of these muscles do other things. Some externally rotate the hip, others internally rotate the hip. Some flex the spine, others adduct the femur. This means the action of hip flexion can be done many different ways, with several different positions for the femur. How can we help clients and students perform this movement in an efficient way?

To assess standing hip flexion:
I have all of my new clients place their hands on a bar in front of them to remove the balance challenge. (Eventually, I want people to be able to flex their hip without holding on to anything, but in the beginning, I am simply assessing their ability to do this movement). I ask the person to shift his weight to the left so he is strong through his left leg and lift the right foot off the ground. Does he lift his right ASIS up as he lifts his right foot? Does the right hemipelvis move forward or back? Does he grip in his jaw or claw the toes of the standing leg? In my more mobile folks, I check for movement in the spine and/or head as the foot lifts (those dancer types are tricky and can make movement appear using strategies I have never considered). If any of these things occur, where do I start?

Before we jump to conclusions and assume the individual is weak/pathological/has a weak core/has some other muscular weakness or imbalance, ask yourself if it’s possible the person simply doesn’t know how to do this. Maybe he doesn’t understand how to dissociate movement from his hip and his back, or maybe he doesn’t know how to lift his foot without relying heavily on bending his knee because he hasn’t been asked to do it any other way before. 

This isn’t to say the person lacks strength; these days, I find most general population clients do lack strength. That’s why they hire me. But there is also a coordination issue, and if I don’t teach the individual how to flex his hip standing, chances are low he is going to be able to work in positions like tall 1/2 kneeling or any sort of squat comfortably (we will talk about the squat in part II next month, but hopefully we all understand hip flexion is a fundamental component of successfully squatting). 

Other things to consider when assessing open chained hip flexion is it’s not necessarily an issue of only hip flexor strength. Guex, et. al (2016) point out hamstring strains in sprinters tend to happen during the late swing phase during gait when the hamstrings are eccentrically contracting to decelerate knee extension and the hip is flexed. Last summer, a 76 year old client strained his hamstring when he misjudged the height of the stair he was climbing; this is the same action of controlling knee extension and flexing the hip.

It stands to reason improving hip flexion strength and control would improve hip extension. Think about it; when you go into hip flexion with the right leg, what is the left hip doing? It’s probably in a little bit of extension to stabilize the pelvis. Even if you are in a 1/2 kneeling position with the right leg forward, the right hip is flexed, and the left hip is in extension. This is beneficial; a 2016 study looking at dancers with hip pain found a) dancers are susceptible to hip pain that mimics symptoms of femoral acetabular impingement (FAI) even though their scans show normal hip pathology b) dancers with FAI-like symptoms are thought to lack the strength to adequately control the extreme ranges of motion required for dance and c) dancers with FAI type symptoms lack strength in active hip extension when compared to asymptomatic dancers (Kivlan, et.al, 2016). 

Chances are high at some point you will work with someone complaining of pain in the front of the hip. If you place the femur in flexion, adduction, and internal rotation (standard impingement test), the person will likely feel a pinching in the front of the hip. Your instinct might be to avoid hip flexion, but to actively train hip extension, teaching the client how to flex without pain and then extend the hip can do wonders. (I work with a fair amount of these individuals. They present with a positive pinch test at the beginning, we work flexion and extension emphasizing a “neutral” knee and foot position, and the pinching sensation is gone by the end of the session. This is not magic. It is simply giving the body other options. The changes will not stay unless the client continues to work on hip strength). A simple way to think about this is the client has a bias (perhaps) towards internal rotation. Teach flexion with external rotation. Given the list of muscles above, it should make sense this accesses a different hip flexion strategy.

Back to our client assessment. Let’s pretend when he lifted his right foot, his right hip hiked up. When you place hip in 1/2 kneeling with his right foot forward, you are (probably) going to see the same pattern of the right hip hiking up. We aren’t quite sure why he is coupling hip flexion with pelvis movement or, at least, I’m not. Potential reasons include ones I have already discussed (weakness in flexion, lack of motor control). There might be positional issues, a lack of strength in the stabilizing leg, a flexibility issue, or plain old deconditioning, aka weakness all over. 

Motor control:
To tease out where to begin, I start with motor control. I can cue until I am blue in the face, but if the client doesn’t understand what I am asking him to do, I am not setting him up for success. I approach this two ways. First, I teach the person how to move his pelvis while seated so he understands where his ischial tuberosities are located. This gives the individual a sense of pelvis position; doing it seated offers proprioceptive feedback, which is always useful when you are first teaching someone how his body moves. I frequently use a variation on seated Feldenkrais pelvic clocks, an example of which can be found here.  Notice this isn’t about muscular effort, releasing tight muscles, or firing anything. It’s simply teaching awareness of movement. 

If the person is struggling with feeling the ischial tuberosity against the bench, I roll up a little towel and have the person place it under his sit bone. Aha! More feedback! This usually stimulates a stronger sense of the ischial tuberosity; once the towel is removed, the person finds it much easier to feel his ischial tuberosity against the bench.

What does this allow me to do? Now when the individual stands up and flexes his right hip, if the right pelvis lifts, I can ask him to drop his right sit bone and he will know what this means. (I can do the same thing in 1/2 kneeling; however, this tends to be more challenging if he has any sensation of tightness in the hip). 

Strength:
Next, I have him lie supine on the floor with his knees bent. I ask him to lift his right foot off of the floor. If there is abdominal bracing OR the pelvis tips to the right or left, I know I need to work on strength. Abdominal bracing indicates a high threshold strategy for a movement that should be pretty mellow (it is also indicates the person has figured out the goal is to not move his pelvis; bracing is his solution). The pelvis tipping to one side or the other indicates a lack of control in the muscles that keep the pelvis stable. We can call these lots of things depending on what you study (deep front line, inner core, core stabilizers..). I like to think of this as a pelvis that has a hard time remaining still. 

If either bracing or pelvis movement occurred, I use typical core stability exercises and breath work to help the person find a sense of stability. Supine arm reaches on the exhale, cat/cow with cat holds, forearm planks, and crawling regressions with breath are all examples of exercises I use to reduce bracing/improve a sense of stillness in the pelvis. I also reduce the movement; instead of having the individual lift his entire foot, I work on lifting the heel. I cue the person to feel the movement at the hip crease that occurs when the heel lifts so he can begin to establish a connection with how the movement occurs.

(Dean Somerset has a good demonstration of breathing impacting the straight leg raise, aka hip flexion with a straight leg. The video can be found here, and offers a good explanation of nervous system response. 

Flexibility:
What about the person that is actually tight? I work isometric positions of the hip. I typically start with a very low step. I have the individual place his right foot on top of the step and get the sense that the pelvis is relatively level now that he knows how to do this. I like to start with the right foot relatively straight and the sense that the right heel, big toe, and pinkie toe are all pressing into the step. From here, I ask the client to move his knee in and out a little bit, while keeping the weight on the foot. Often, people find letting the knee move in is easy; out is a bit harder, so I will have the individual hold with the knee pointing straight ahead (it’s sort of like a standing isometric clam shell). 

I also train hip extension. As noted, this goes hand in hand with hip flexion. If you are working individuals in 1/2 kneeling, remember the goal is to extend hip of the back leg. The easiest way to do this is to generate force down with the back knee. (Charlie Weingroff has a great variation of this on his DVD “Training=Rehab.” Tony Gentilcore explains it well in this video here). You can also progress towards dynamic flexibility and strength by straightening the back leg and lowering it down with the hands on block, torso slightly forward so your head, hips, and back ankle form a line. (Demo here). This comes from the GMB Focused Flexibility system.

(The image above is a great way to prep for backbend work. This is not isolating hip extension. It doesn't make it wrong or a bad movement; just make sure you know why you are performing it this way and ask yourself, "is this accomplishing what I want it to accomplish?").

Eventually, I progress all of my clients to various forms of hip flexion with internal and external hip rotation. We train multiple angles, both standing and in 1/2 kneeling. Incorporating hip flexion into a client’s routine can have profound effects on flexibility and strength at the hip and pelvis. Ultimately, the idea one movement or muscle is “bad” and needs to be minimized or banned from training doesn’t benefit our clients. Train awareness and strength in multiple positions; flexibility will follow. 

Yours in health and wellness,
Jenn

References:
Clippinger, K., (2006). Dance Anatomy and Kinesiology. Champaign, IL: Human Kinetics.
Geux, K., Degache, F., Morisod, C., Sally, M., & Millet, G.P., (2016). Hamstring architectural and functional adaptations following long versus short muscle length eccentric training. Frontiers in Physiology, 7(340), 1-9. 
Kivlan, B.R., Carcia, C.R., Chritoforetty, J.J., and Martin, R.L., 2016). Comparison of range of motion, strength, and hop test performance of dancers with and without a clinical  diagnosis of femoral acetabular impingement. International Journal of Sport and Physical Therapy, 11(4), 527-535.