Mastering the Role of Hip Flexors in Running: Anatomy to Strengthening

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Cross Training For Runners
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David Dack

Have you ever caught yourself wondering about the role of your hip flexors during your morning jog? I sure have. In fact, it was a question that sent me down a rabbit hole of fascinating discoveries about how the human body—mainly the muscles—function while logging the miles.

Let me tell you, running is more than just cardio exercise; it’s a complex, beautifully orchestrated movement. Each muscle, bone, and joint plays its part. And in this ensemble, the hip flexors are some of the most reliable players in every stride we take.

In this post, I’m going to take you through the world of hip flexors, the muscles I’ve come to appreciate so much in my running journey. We’ll dive into their anatomy, their critical role in our running stride, and why ignoring them is as risky as running with loose shoelaces.

And, I’ll share with you some of the best ways I’ve found to keep these muscles not only strong but also flexible, helping you to run longer, faster, and free from pain.

Sounds like a good idea?

Let’s get going.

Anatomy of the Hip Flexors

Understanding the roles and functions of hip flexors in running is crucial for any runner. Let me break down this for you:


The iliopsoas, comprising the iliacus and psoas major muscles, is a major muscle group in the hip flexor family. Located deep in the abdomen, it connects the lower spine and pelvis to the upper thigh bone (femur). Its primary function is lifting the thigh toward the body, an essential action in running.

I learned about the iliopsoas the hard way. A few years ago, I ignored a nagging pain in my lower abdomen, only to find out I had strained my iliopsoas. That was a two-week rest I’ll never forget, a stark reminder of the importance of these muscles.

Rectus Femoris:

This muscle is part of the quadriceps group and is unique because it spans two joints – the hip and the knee. It attaches at the hip bone and the patella (knee cap). While it’s primarily involved in extending the knee, it also aids in hip flexion, playing a dual role in both lifting the leg and contributing to forward propulsion during running.


The longest muscle in the human body, the sartorius extends from the outer hip to the inner knee. Its unique position allows it to assist not only in hip flexion but also in the outward rotation of the thigh. In running, it contributes to the lateral stability and movement of the leg.

Hip Flexors and Running Efficiency

The role of hip flexors in running efficiency is like having a finely-tuned engine in a vehicle – the better its condition, the more efficient the performance.

Let me explain more:

Efficient Stride Mechanics:

Robust and supple hip flexors are pivotal for optimal stride mechanics. They enable a broader range of motion, leading to a more effective leg swing during each stride.

Reduced Energy Expenditure:

Well-conditioned hip flexors minimize the effort required to lift and drive your legs forward. This increased efficiency translates to reduced energy expenditure for the same amount of work.

Don’t take my word for it. A study published in the Journal of Sports Sciences found that improved hip flexor strength can lead to better running economy, as it reduces the oxygen demand for a given running speed.

Impact on Speed and Endurance:

Strong hip flexors can positively influence both speed and endurance. By facilitating quicker leg turnover and longer strides, they boost how fast you can run.

A 2018 study in the Journal of Strength and Conditioning Research highlighted the link between hip flexor strength and endurance performance, implying that targeted hip flexor training can benefit long-distance runners (more on this later).

Injury Prevention:

Flexible and strong hip flexors also play a role in injury prevention. Tight or weak hip flexors can lead to imbalances and compensatory movements, increasing the risk of injuries.

By maintaining the health of these muscles, you might be able to reduce your risks of common issues such as lower back pain or hip joint problems. Research in sports medicine consistently points to the importance of hip strength and flexibility in reducing overuse injuries in runners.

Downsides of Weakness

The significance of hip flexors in running cannot be overstated, and recent research, including a study from Stanford University, underscores this. The study found a correlation between hip strength and knee pain in runners, revealing that those with knee pain often had weaker hip muscles compared to those without injuries.

The Stanford study highlights that weaker hip muscles makes you more prone to knee pain while running. This is due to the hip flexors’ role in stabilizing the pelvis and affecting lower limb mechanics.

The same research reported that runners suffering from knee pain showed significant improvement after a six-week hip strengthening program.

Here two of the most common hip flexor injuries to be wary of:

  • Strains: Hip flexor strains are common and occur when the muscles are overstretched or torn. The severity can vary widely, from minor tears causing discomfort to complete ruptures that are far more serious.
  • Tendinitis: This condition involves inflammation of the tendons in the hip flexor muscles, typically due to repetitive stress or overuse. It can be thought of as similar to a rope gradually wearing down from persistent friction.

Preventing Hip Flexor Injuries

Here are a few measures I’d recommend any runner to take to prevent hip flexor injuries:

Proper Warm-Up:

Before diving into a run, a warm-up primes your muscles for the activity ahead. I’d recommend a dynamic warm-up.  This includes movements like leg swings or gentle jogging, increases blood flow to the muscles, making them more pliable and less prone to injury.

Stretching Routines:

Regular stretching improves flexibility, which can prevent overstraining. Post-run stretching is especially helpful for the hip flexors, as it helps lengthen the muscles that have been actively contracting during your run, helping release any running-induced tightness.

Exercises for Strengthening and Flexibility

It goes without saying but strength training is the best way to fortify your body against common overuse injuries. Here are a few exercises that specifically target your hip flexors.

  • Standing Hip Flexions: Stand and lift your knee towards your chest, then lower it back down. For added resistance, use an ankle weight or resistance band.
  • Lunges: Step forward into a lunge position, ensuring your knee doesn’t go beyond your toe. This strengthens the hip flexors while engaging the whole leg.
  • Bridges: Lying on your back with knees bent, lift your hips towards the ceiling. This strengthens the glutes, which helps support the hip flexors.

Flexibility Exercises:

Stretching is also key. Having a proper range of motion in your hips not only helps you move more freely but may also reduce the load on your lower body. That’s a good thing if you ask me.

Here are few stretches to add to your routine:

  • Psoas Stretch: Step one foot forward into a lunge position and shift your weight forward, stretching the hip flexor of the back leg.
  • Butterfly Stretch: Sitting, bring the soles of your feet together and gently press your knees towards the ground. This opens up the hips and stretches the inner thighs.

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