Chronic Hip Flexor Pain? One Surprising Exercise That Helped

Daily Running, Chronic Hip Flexor Pain, and an Unexpected Change After Bulgarian Split Squats

I run every day. Around four kilometers, mostly easy pace. I have done this consistently for more than five years. In addition, I regularly play football and futsal.

For almost a year, I have had a recurring hip flexor issue. It never reached the point of stopping me from running, but it also never fully resolved. The pattern was consistent: it felt worse when runs were close together, flared after football or futsal, then partially settled, only to return again.

After seeing this topic repeatedly discussed in endurance sports content, especially among runners, cyclists, and triathletes, I assumed this was a common overuse problem. That assumption was confirmed in a conversation with a runner friend who described the exact same symptoms and timeline.

During that conversation, he mentioned that Bulgarian split squats had helped him significantly over the previous two weeks. He had not changed his running volume. The only new variable was this one exercise.

I decided to try it.

I did a short session of Bulgarian split squats with no added weight. The movement immediately exposed a lack of quad strength, despite years of daily running. Two days later, I had severe delayed onset muscle soreness in my quadriceps.

That part was expected.

What was not expected was what happened during the next run.

Despite significant quad soreness, the usual hip flexor discomfort did not appear. This raised several questions that are worth unpacking.

Question 1: Can one exercise meaningfully change a long-standing issue?

Yes, but not by building strength.

Muscle hypertrophy and strength adaptations take weeks. However, changes in muscle activation and load distribution are driven by the nervous system and can occur very quickly. A single, well-targeted stimulus can alter which muscles take priority during a movement like running.

In this case, the Bulgarian split squat forced knee-dominant loading and quad engagement that running alone had not been providing.

Question 2: Is this just placebo?

Placebo can influence pain perception, but it does not fully explain:

severe, muscle-specific quad soreness

side-to-side differences in soreness

consistent symptom changes during a known trigger activity

A more plausible explanation is that load was redistributed. The quads began contributing more, reducing chronic overuse of the hip flexors.

Question 3: Why would quad weakness affect the hip flexor?

Running is repetitive and forgiving. If one muscle group underperforms, another compensates. Over time, this can create low-grade strain without obvious injury.

If the quads do not adequately handle braking and load acceptance, the hip flexors can take on stabilizing roles they are not designed for. This can result in persistent irritation rather than acute injury.

Question 4: Why did the hip flexor feel better while the quads felt worse?

Delayed onset muscle soreness indicates novelty and underuse, not damage. At the same time, reduced hip flexor discomfort suggests lower ongoing strain.

In other words, the system did not heal overnight. It changed how work was shared.

Question 5: Does this mean the problem is solved?

No.

This type of change is fragile. If quad loading is abandoned or progressed too aggressively, the previous compensation pattern can return. The improvement does not mean the hip flexor tissue has healed, only that it is currently being stressed less.

What this suggests

Daily easy running can still maintain a chronic overuse loop if load distribution is poor. Low intensity does not guarantee recovery if frequency remains constant and no other tissues are prepared to share the work.

Introducing targeted strength work can reduce background strain, not by stopping activity, but by changing how that activity is supported.

For now, the practical takeaway is not a prescription, but an observation:

Sometimes the painful structure is not the primary problem. It may simply be the one compensating for something else that has been underloaded for a long time.

Why I’m Posting This Here

This topic is outside what I usually write about. I am not a coach, a physio, or a medical professional, and this is not training advice.

I decided to publish it anyway because this issue occupied a disproportionate amount of mental space for nearly a year. It never stopped me from running, but it never fully resolved either. The fact that such a small, specific change appeared to alter that pattern made it worth documenting.

At minimum, it is a concrete observation about how long-standing, low-grade issues can persist even with “light” daily activity, and how changing load distribution, rather than volume, may matter more than expected.

Whether this holds long term remains to be seen. For now, it is simply a record of what changed and why it caught my attention.