Why hip flexion isn’t bad part II: (aka using closed chain exercises to strengthen the hip)

In part I, I made the argument for hip flexion. Part II will examine close chained hip flexion and its application to moving well.

Confession. I have a bias towards this topic. I am someone who used to think everyone’s hip flexors were “tight.” I slowly came to realize that was absolutely not the case, and many people actually have hip flexors that are weak. And then along came the case of the sore hip.

I wrote about the case of the sore hip here. The cliff notes version goes something like this: for about 18 months, I had a sense of tightness in the anterior compartment of my left hip. During this time, I was partnered with a chiropractor at a workshop who basically told me my lack of hip extension was sure to cause me impeding doom in the form of low back pain later in life (note to self: doomsday talk doesn’t make the person you are working with feel very hopeful. Also, maybe unsolicited advice should be avoided at workshops?). This resulted in lots of hip flexor stretching.

Guess what? Stretching my hip flexors (not my low back and maintaining a glute contraction) gave me a sense of relief. Temporarily. (All of you that follow these sorts of stories are wondering what I expected). 

Fast forward to the fall of 2015, when I was doing a lot of deep squatting, hopping in deep squatting, and transitioning in deep squatting. I was also doing closed chain mobility work and not stretching my hip flexors. Gradually, the sensation of tightness went away until I no longer had any discomfort at all. In retrospect, I likely had a hip flexor tendinopathy. Tendinopathies typically occur near the bone/tendon junction; compression of the tendon tends to make things worse initially (Cook & Purdam, 2011). Compression occurs when the tendon is being pulled around the bone, which is what we are doing when we stretch.* The goals isn’t to avoid stretching the tendon forever; however, avoiding stretching for a little while and getting the tendon strong at different angles can go a long way in allowing the tendinopathy to heal.

Enough about me and my bias. Let’s talk about closed chain hip flexion.

Closed chain versus open chain:
First, I thought I would take a moment to clarify the difference between closed chain and open chain exercises. The textbook definition of an open chain exercise is the distal segment of the extremity is free to move through space (Ellenbecker & Davies). These exercises often take place at one joint, which allows a higher level of joint isolation to occur. This can be beneficial for teaching a person how a joint works.

For instance, a supine straight leg raise (pictured below) is an example of an open chain exercise. The hip flexes to lift the leg up. Ideally, the pelvis stays stable, isolating the movement to the hip joint.

Closed chain exercises, on the other hand, occur when the distal segment is more or less fixed and free motion is restrained. Often, multiple joints are involved in order for movement to occur.

With a squat, the feet are fixed while the hips, knees, and ankles flex to allow the hips to move closer to the floor. The stress pattern in a closed chain exercise is linear, while in an open chain exercise it has more of a rotary component.

One type is not necessarily better than the other. They are different and can be used to teach different things. We use both in everyday life; when I reach for the cup in the upper shelf, I am performing an open chain movement with my upper extremity; when I plant my hands on top of the counter and use my arms to press myself up on the counter so I can see what’s in the top shelf, I am performing a closed chain movement with my upper extremity. (Before you judge, I am 5’1”; in my world, counters exist to make me taller).  

Research suggests from a rehabilitation perspective, closed kinetic chain exercises may be favorable early in the rehabilitation process because they have more proximal joint stability and less shear force than open chain exercises (Kang, et.al, 2014). They also are better at restoring proprioception and appear to result in better long term strength and function outcomes after surgery (Zhang, et.al, 2014).

I think most of us can agree this makes sense. What feels more secure: placing a hand against a wall and pressing it away from you or holding a soup can and pressing it forward? More than likely, pressing the wall away from you feels more secure in your mind’s eye than the soup can scenario. From a motor control standpoint, there is less to control when you press the wall away, as opposed to a fairly light soup can, whose trajectory forward is less clear. 

Closed chain hip flexion:
So now that we have clarified the difference between open and closed chain exercises, let’s look at how this can be applied to hip flexion.

Perhaps the most obvious example of a closed chain exercise to strengthen the hip is the squat (Kim, et.al, 2015). Controlling the movement downward requires strength and mobility in the ankles and hips. (Quick aside: if someone struggles with a rib flare, center of mass will be thrown off. Some people have the mobility to compensate for this; others, like yours truly, are much better off dealing with the rib flare before addressing hip flexion and ankle dorsiflexion). I tend to address mobility and strength together after I take the person through a framework of sensing, feeling, and adjusting the ankle and hip in isolation. There are many different opinions on the “right” way to squat; for the purposes of this blog, I am using the example of the bodyweight squat. 

In part I of this series I discussed the fact the muscles that control hip flexion don’t just flex the hip; they also adduct the thigh, extend the knee, externally or internally rotate the femur, or abduct the thigh, depending on where they are located and the type of movement. This is great because it gives the practitioner a chance to be creative. Let’s briefly discuss options for exploring the squat as a closed chain exercise.

The “right” way to bodyweight squat:
When my goal for the bodyweight squat is to teach hip flexion, I don’t allow the pelvis to roll under; I have the person squat down to the lowest point he can before this happens. However, when the squat is being used as a resting position, there is nothing wrong with the pelvis posteriorly tilting.** 

Remember the multiple muscles used during hip flexion above? This is where a little bit of anatomy knowledge can be helpful. Try this. Take your feet about hip distance apart and squat down to your lowest comfortable point. Now, take your feet close together and do the same thing. Finally, take your feet really wide and do the same thing. Which one feels most comfortable? Did your feet change angles in the different positions? And which one ifs “right?”

One of the great things about squatting is there are several variations, with different names, that target different angles of hip flexion. As a result, I would argue there is no “right” way to bodyweight squat; only different variations, so find the way that works best for you or your client. Once you are comfortable with that variation, try another. This will strengthen the hip at different joint angles.

A brief note on knee position:
It has been suggested increased knee valgus during squatting and single leg squatting may indicate increased risk of ACL injury (Dill, et.al, 2014). I work primarily with the general population, and my thoughts on this are as long as your only option isn’t to go into knee valgus every time you squat, it’s okay if sometimes your knees go in (again, remember, this is a bodyweight squat). If you work on the squat as a transitional movement, there will be times when the knee is at a “less than optimal” position, but again if you are part of the camp that believes loading tissue at different angles makes it stronger, this isn’t necessarily a bad thing. However, if the knees caving in is your habit every single time you squat down, learning to squat while maintaining control at the knee joint increases the ways you are able to squat. Options are good.

Teaching pelvis and hip position in a squat:
So now let’s focus on how to teach someone the different between hip flexion and pelvis tilting in the squat position. This can be a little bit tricky, and begins with sensing where the body parts are located.

If you ask most people where their hip is located, they will gesture to their gluteus maximus. There tends to be a bit of surprise when they realize the actual hip joint is a little more anterior than that. It is easy to understand why people frequently get the hip and the pelvis confused. 

The easiest way to help a client sense the hip versus the pelvis is to have him lie on his back with his knees bent, feet flat on a wall about hip distance apart (or maybe a little wider, depending on flexibility). In this position, ask the person to feel the weight of the pelvis against the floor (you might even have him take his hands to the ASIS to feel whether they are level). Keeping everything still, ask the person to lift the right foot just a little bit away from the wall, feeling the movement from the hip. This is essentially a squat on the back and can be a useful way to teach position.
https://www.youtube.com/watch?v=tgP6ZZYddTY

The next step is helping the client understand active hip flexion. The tricky part of squatting is it’s easy to let gravity pull you down into a squat; controlling the movement is a little more challenging. 

There are two ways I like to do this. The first is with a quadruped rock back, as seen below. Cue the client to move from the hips (some respond well to cueing the sitting bones moving back, others to creasing the front of the hips. Play with the words to find what works for the person in front of you). I like to have the person move slowly at first, gaining a sense of control, before increasing speed. I also like the ankles dorsiflexed if I am working on this as a precursor to the squat. 
https://www.youtube.com/watch?v=U2vPEZw7S2I

The next way to do this is using towel slides, like I am demonstrating below. I am performing bent leg and straight leg variations; again, if I am working on the squat with a  client, I would stick to the bent leg variation. This requires a good understanding of how to flex the hips and is a great way to build control in hip flexion.
https://www.youtube.com/watch?v=GCDs4i9q4kI

Putting it all together:
Once the client understands the basic components of the movement, it’s much easier to teach the actual squatting movement. Ask the client to lower down into a squat position slowly, feeling the movement coming from the hips. *I’m not addressing ankle dorsiflexion or thoracic spine position in this blog, but if things looked fine in the other positions and the person cannot perform the squat movement, as mentioned above, these can be limiting factors.* Let the feet be in a comfortable position and allow the person to focus on the sense of lowering down slowly.

When the bodyweight squat is understood and becomes a movement the client is comfortable with, using the bodyweight squat as a transition can be an excellent way to strengthen the hip flexors in a variety of positions. Things like traveling ape from the Animal Flow system or frogger from GMB are challenging, fun (in that sort of sadistic way challenging movements are fun), and apply load to the hip flexors.
https://www.youtube.com/watch?v=pG3jXGmX0jM
https://www.youtube.com/watch?v=ATK4BtUyI18

There are many ways to load the hip flexors. Lunging patterns, single leg squat patterns, and, of course, pistol squats, which challenge the extended leg to maintain open chained hip flexion while the squatting leg works closed chain hip flexion are all excellent ways to load the area. If  balance is a problem, a light weight can often provide a bit of stability and add control to the movement.

Finding strength and teaching control goes a long way towards improving a sense of general coordination. Embrace strength and variety for a greater sense of well-being.

Yours in health and wellness,
Jenn

*This video explains tendon compression really well: https://vimeo.com/118162021
**There are two blogs I highly recommend reading you are trying to understand bodyweight squat mechanics and form. The first is Dean Somerset’s series on the butt wink: http://deansomerset.com/butt-wink-aout-hamstrings/
The second is Jarlo Ilano and includes a clear roadmap to improving the bodyweight squat: https://gmb.io/squat/

References:
Cook, J.L., & Purdam, C., (2011). Is compressive load a factor in the development of tendinopathy? British Journal of Sports Medicine, doi: doi:10.1136/bjsports-2011-090414
Ellenbecker, T.S., & Davies, G., (2001). Closed kinetic chain exercise: a comprehensive guide to multiple joint exercises. Human Kinetics: Champagne, Il. 
Kang, M-H., Oh, J-S., & Jang, J-H.J., (2014). Differences in muscle activities of the infraspinatus and posterior deltoid during shoulder external rotation in open kinetic chain and closed kinetic chain exercises. Journal of Physical Therapy Science, 26(6), 895-897.Zhang, F., Wang, J., and Wang, F., (2014). Comparison of the clinical effects of open and closed chain exercises after medial patellofemoral ligament reconstruction. Journal of Physical Therapy Sciences, 26(10), 1557-1560.
Kim, S-H., Kwon, O-Y., Park, K-N., Jeon, I-C., & Weon, J-H., (2015). Lower extremity strength and range of motion in squat depth. Journal of Human Kinetics, 45, 59-69.
Dill, K.E., Begalle, R.L., Frank, B.S., Zinder, S.M., Padua, D.A., (2014). Altered knee and ankle kinematics dring squatting in those with limited weight- bearing- lunge ankle-dorsiflexion range of motion. Journal of Athletic Training 49(6), 723-732.