Introduction
Hip flexor pain is one of the most common complaints you’ll hear from runners. And more often than not, the conclusion is made quickly: their hip flexors must be tight.
From there, the solution feels straightforward: stretch them.
But if you’ve worked with runners long enough, you know it’s rarely that simple. You can stretch, mobilize, and create short-term relief, yet the same runner comes back a few weeks later with the same issue. That’s usually the moment where we have to step back and ask a better question:
Are the hip flexors actually the problem…or just part of a bigger system that isn’t working well?
Understanding the Role of the Hip Flexors
To answer that, we first need to understand what the hip flexors actually do.
Most clinicians think of the iliopsoas primarily as a hip flexor, which is true. But what’s often overlooked is its role as a spinal stabilizer. Because of its attachment to the lumbar spine, it plays a major role in controlling the relationship between the trunk and the pelvis during movement.
That makes it one of the key connectors between the upper and lower body. When a runner is generating force—whether at an easy pace or sprinting—the hip flexors are part of the system that allows that force to transfer efficiently.
So when something goes wrong, it’s rarely isolated to just “tightness.” It’s usually tied to how that system is functioning as a whole.
Where Things Start to Break Down
One of the most common patterns we see with hip flexor dysfunction is the development of an anterior pelvic tilt during running.
At first glance, that might not seem like a big deal. But when you follow the chain of events, it becomes much more significant. As the pelvis tilts forward, we start to see changes in how the glutes function, particularly the glute max. Instead of effectively controlling the swing limb and preparing the body for ground contact, its timing becomes delayed or diminished.
When that happens, the body still has to move forward. So it finds another strategy. Most commonly, that shows up as overstriding.
This is where the connection becomes important. The runner may feel hip flexor tightness, but what you’re often seeing is a compensation pattern driven by pelvic position and poor force control. If you don’t address that pattern, the stress doesn’t go away, it just keeps cycling through the system.
Why Mobility Alone Doesn’t Solve It
This is where a lot of treatment approaches fall short.
We’ve all seen runners improve their hip extension range of motion after stretching. But when you put them back on the treadmill, their mechanics look exactly the same. That’s because mobility doesn’t automatically translate to movement.
Running is a high-speed, high-load activity. It requires coordination, timing, and control, not just access to range. If the body doesn’t know how to use that range under load, it simply won’t. This is why so many runners feel better temporarily after stretching but don’t see lasting change. The input was helpful, but it didn’t change the system.
How Speed Changes the Role and Load of the Hip Flexors
One of the most important pieces to understand is how the body changes its strategy as running speed increases.
Running speed is ultimately a combination of step length and step frequency. At slower to moderate paces, most runners increase speed by covering more ground with each step. This is largely driven by force production during stance, where the gastrocnemius and soleus play a major role in absorbing and generating force.
As speed increases, however, that strategy begins to shift.
Ground contact time becomes shorter, which limits how much force the lower leg can produce. At that point, runners rely more on increasing step frequency to move faster. This is where the hip flexors take on a much larger role, helping to rapidly advance the swing limb and reposition the foot for the next step.
At the same time, the load placed on the hip flexors increases significantly.
At an easier running pace, the hip flexors experience forces of roughly 2 times bodyweight. As speed increases, that demand rises to around 3.5 times bodyweight, and at sprinting speeds, it can reach up to 9 times bodyweight.
So not only does the role of the hip flexors change—they are also being asked to handle dramatically higher loads.
This shift matters clinically. It helps explain why some runners begin to experience symptoms as they introduce speed work, and why simply improving flexibility is often not enough. The system has to be prepared to both control and tolerate the demands of faster running, not just move through available range.
A Better Way to Approach Treatment
If we step back and look at this from a clinical standpoint, the goal isn’t just to “fix the hip flexor.” It’s to understand what role it’s playing in the bigger picture.
That starts with making sure we’re actually identifying the correct source of symptoms. Hip pain in runners can come from a number of different structures, and even commonly used assessments like the Thomas test can be misleading if pelvic position isn’t controlled.
Once we understand the true limitation, the next step is to think in terms of a process rather than a single intervention.
In our model, that process follows a simple progression: test, reset, reload, retrain, and retest.
Early on, you may use manual therapy or targeted stretching to reduce symptoms and improve available range. These inputs can be helpful, especially when they create immediate changes that the runner can feel.
But that’s just the starting point.
From there, the focus needs to shift toward building capacity. That includes strengthening not only the posterior chain, but also the hip flexors themselves (something that is often underemphasized). At higher speeds, these muscles are handling significant loads, and they need to be prepared for that.
At the same time, you have to address trunk and pelvic control. If the pelvis isn’t stable, the body will continue to compensate no matter how strong or mobile the athlete becomes.
Making It Transfer to Running
The final piece is making sure that these changes actually show up in how the runner moves. This is where gait retraining comes in.
Even when strength and mobility improve, runners tend to fall back into their habitual movement patterns. Those patterns are learned over thousands of steps, so changing them requires intentional input.
Clear, simple cues can go a long way. Something like “run long” often works better than telling someone to “stand tall,” as it promotes a more natural alignment without encouraging excessive lumbar extension. Drills can help reinforce these concepts, giving runners a way to feel the difference before trying to apply it during a run. Over time, with consistent feedback, the new pattern becomes more automatic.
Bringing It All Together
When you look at hip flexor pain through this lens, it becomes clear that it’s rarely just about tightness. It’s about how the pelvis is positioned, how force is transferred through the system, and how the runner coordinates movement under load.
If we only focus on stretching, we’re addressing one small piece of that puzzle. But when we take a more comprehensive approach, combining mobility, strength, control, and retraining, we give runners a much better chance of not only getting out of pain, but staying out of it.
And ultimately, that’s the goal.
These principles are explored in greater depth in our webinar, Are Tight Hip Flexors Really the Problem? A Paradigm Shift in Treating Hip Flexor Pain in Runners, where we walked through the biomechanical role of the hip flexors, rehab exercise suggestions to incorporate, and gait retraining methods to see lasting improvement.
Watch the full webinar here.