Hip Anatomy

Mastering the Runner’s Hip Flexors

The hip is a complex beast. It’s got lots of muscles, tendons, fascia, blood vessels, and other internal structures. It needs to be…

Mobile enough to get through our day to day life.
Strong enough to help us kick into extra gear when we are on the track.
Durable enough to keep us efficient on a longer effort. 

How does it handle so many different tasks?
That’s what this blog series is here to help with!
In part I, we are covering the hip flexors. Before we get to that specific muscle group, let’s cover some important concepts that will help through the series. 

If you are more of a visual learner, you can also check out this video. 

Key Concept: Muscle Pathways

If you have taken an anatomy class, you’ve likely learned about muscle origins and insertions. They depict how our muscles originate in one location and attach somewhere else. These are like road maps that our muscles travel in the body. This relationship allows our body to move when we contract our muscles. If we look at a graphic of the front of the hip and pelvis, it looks like the we lost a paintball match. 

There’s a lot of stuff!

Key Concept: Bone’s Adapt in a Direction Specific Manner

I talk about bones a lot. A key principle with bone is it adapts in a very specific manner. Our bones only get stronger if we stress them. They also only get stronger in the direction they are stressed. If we twist them they get better at being twisted. If we pull them they get better at being pulled. If we don’t stress them in a specific direction, they aren’t necessarily strong in that direction. 

To me, that means we should stress our hip a few different ways to make sure it’s in a good position to deal with running.

Instead of doing the same thing over and over… 

*cough* running *cough*

…we should have it deal with a variety of stressors. Running doesn’t give us that opportunity. While our hip still has to go through many motions while running, we need higher loads to make these tissues stronger.  

How do we do that?  

It’s pretty easy to separate the hip into four different sections.

Anterior, posterior, medial and lateral.

That’s the same way we look at dividing the body anatomically. I want to make sure runner’s have at least one exercise per section in their strength routine at all times. Their individual architecture, injury history, and specific event will cause me to tweak some specifics a bit. Specifics aside, I want all my runners having an exercise in each category. 

Key Concept: Lines of Pull

Let’s go back to those origins and insertions. That paintball diagram highlights where our muscles start and end. Each one of those dots represents a muscle that travels a different path and angle to find its final destination. When each muscle contracts it pulls at specific manner. Since our muscles all work together, it’s like a gigantic tug-of-war occurring while we run. . 

When our foot hips the ground our hip has to extend, rotate in, and adduct (get closer to midline). As our foot comes off the ground our hip has to flex, rotate out, and abduct (move farther from midline). This oscillation back and forth is constantly adjusting which lines are winning the tug of war.

All these muscles are in the game so we want to make sure they are ready for the task. 


This image above image depicts the attachments of our hip flexors. Runners will complain of soreness, tightness or fatigue in their hip flexors. That makes complete sense because of the amount of stress they deal with when running. This group of muscles plays an important role in running.

What exactly do the hip flexors do when we run?  

Muscle GroupHip Flexors: Rectus femoris, iliacus, psoas, sartorius, and rectus femoris
Function1. Active Hip Flexion
2. Eccentric loading into hip extension

The first role of the hip flexors is to bring our knee towards our chest. Flexing our hip in this manner makes sure we don’t trip and fall on our face. As we run faster this motion becomes even more important. The faster we run, the more we flex our hip. We also will engage more hip flexion if we are running up an incline.

As our hip extends behind our body, we start to store some energy in the front of our hip. Like pulling back a rubber band to fire, our hip flexors have to tolerate that stretch before releasing our leg forward. Like with hip flexion, the faster we run, the more force we have to handle in that sling shot. Contrary to popular opinion, we don’t need much hip extension to run, but we do want to be able to generate a lot of force in our hip to powerfully drive it forward.

Making sensible training decisions is the first step to allowing our hip flexors to adapt to running. There is always more we can do. Isolated exercises in the weight room can help prep the front of the hip.

Here are a few of my favorite hip flexor drills then let’s wrap this up below!


*The hip has to deal with a variety of loads and stressors in life and with running.
*The anatomy of our muscles impacts how we should prescribe exercise
*Running faster and running up inclines place more demand on the hip flexors
*We should actively challenge the hip flexors in the weight room.

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