Hip Flexors: What Are They For and Why Should You Care?

As I just qualified as a Level 2 personal trainer over the weekend, I thought it would be appropriate to focus specifically on some usually neglected running muscles in this week's blog post. Most runners know that quads and hamstrings, or even glutes, are important to running form. But now hip flexors are often forgotten. To be honest, until reasonably recently I didn't appreciate myself what hip flexors did (or rather didn't do!) for my running and why it was important in my case to stretch them.

What are hip flexors?

Hip flexors is a general term to cover five muscle groups that allow the femur to flex towards the pelvis. Hip flexors are primarily made up of the iliopsoas, sartorius and rectus femoris muscles.

Main hip flexor muscles

Why do they matter?

If your hip flexors are extremely tight, they will likely cause lower back pain because the iliopsoas are attached to the lower thoracic and lumbar vertebrae. But most importantly for running, they may not allow you to push your leg sufficiently behind you (hence preventing your hip extensors to do their job properly), affecting your biomechanics and running economy. Hip flexors tightness affect a great deal of long distance runners, especially those vulnerable like me who have a desk job AND weak glutes. On the other side, if your hip flexors are weak, it will likely lead to body imbalance and result in long term issues such as Illiotibial band syndrome (ITB), patellofemoral pain syndrome (also commonly referred to as 'runner's knee' - see my previous blog post on this specific subject) amongst others. Both tightness and weakness will affect your running and cause issues in the long term, so best to address them soonest.

How do I find out whether my hip flexors are tight or weak?

This very good video will provide you with some tests to determine whether you are suffering from weakness or tightness in your hip flexors.

My hip flexors are tight, what should I do?

Stretch them on a regular basis! I myself strech them for 30s after each and every single run I do. A good simpler stretch for hip flexors is the extended lunge. It starts like a lunge but the back leg is pushed further back until a stretch is felt in the hip flexor, as illustrated here. But beware that stretching may not be sufficient if the tightness is due to other physiological dysfunction such as core weakness. If the tightness persists despite the regular stretching, my advice would be to see a physio who will be best placed to assess the cause of the tightness and recommend appropriate action.

One way to stretch your hip flexors

My hip flexors are weak, what should I do?

If weakness of the hip flexors is suspected, then the best way to address it will be by strengthening them. Exercises like side leg raises, diagonal lifts (also known as the 'bird dog' exercise) will help.

Whether you think you may be suffering from tight or weak hip flexors, do not ignore the symptoms and address them now so it doesn't lead to injury.

Happy injury-free running!