In this post, we discuss why you can’t improve your hip flexibility, and why it might have more to do with your parents than your muscles.
If you’ve ever sat in a yoga class and looked around wondering why others seem to effortlessly achieve positions that you find impossible, the answer might not be more yoga.
You’ve probably noticed that humans all look a little different from the outside. Well, they also look a little different on the inside too. This fact is often not considered in exercise classes and personal training.
The structure of our joints varies enormously from person to person, and as structure governs function, this will decide how much motion you have available at your joints.
The architecture of the hip
The hip is a ball-and-socket joint. The ball is the head of the femur (thigh bone), and the socket is the acetabulum — a cup-shaped cavity in the pelvis. This much most people know. What’s less commonly appreciated is just how dramatically that architecture varies from person to person.
The depth of the socket varies, as does the direction it faces. A deep socket creates a more stable hip joint with less available motion, whilst a more shallow socket allows for more motion but is inherently less stable.
The rotational orientation of the femoral neck — called femoral version — also varies considerably between individuals, ranging from anteversion (pointed forward) to retroversion (pointed backward). This has implications for how much internal and external rotation is available at the hip.
These aren’t minor differences. A deep, forward-facing socket and a femur with high anteversion will produce a very different range of motion than a shallow socket with a more neutral femoral neck angle — even if both people have identical muscle flexibility, identical tissue health, and identical training history.
Stretching can’t change bone
Muscles, tendons, fascia, and joint capsule tissue can all adapt over time with appropriate loading. Bones cannot be lengthened, reshaped, or repositioned through training. The orientation of the acetabulum is set. The angle of the femoral neck is set. These are structural facts about a person’s body, not deficits to be corrected.
This matters enormously when it comes to prescribing — or pursuing — flexibility work. If a movement is restricted because of tightness in the hip flexors, then targeted exercise may make a difference. If the restriction is bony, no amount of stretching will produce more range. The joint simply doesn’t have it to give.
The concept of bony impingement
When the hip reaches the end of its available range — a range determined by its geometry — the bones themselves can make contact. This is called femoroacetabular impingement (FAI), and it comes in a few forms. In pincer impingement, the socket rim covers too much of the femoral head, so deep flexion causes the neck of the femur to push into the edge of the socket. In cam impingement, the femoral head isn’t perfectly round, so as it rotates in the socket it begins to make contact with the cartilage.
But impingement isn’t only a pathological diagnosis. Even healthy hip joints with normal anatomy will experience bony contact at the extremes of motion. It’s just that where those extremes are depends entirely on how the joint is shaped.
This is why the deep squat is accessible to some people and genuinely unavailable to others — and why the latter group isn’t failing for lack of effort or commitment. For them, the movement hits a hard endpoint not because of tension in the muscular system, but because bone is running into bone.
The danger of forcing the issue
When a person cannot reach a certain position and continues trying to force their way there — through aggressive stretching, loaded movements at end range, or repeated high-repetition work in positions the joint can’t cleanly access — the joint pays the price.
If the joint is the barrier and you keep pushing, something has to give. Often it’s the labrum — the ring of fibrocartilage that deepens the socket and plays an important role in joint stability and load distribution. Labral tears are painful, can be slow to heal, and in severe cases require surgical intervention. Beyond the labrum, repeated impingement can contribute to cartilage damage over time.
How to tell the difference
Distinguishing a muscular restriction from a bony one in a clinical setting requires a trained eye — or in complex cases, imaging.
I can’t tell you the number of times I’ve come across a hip that doesn’t want to move in a particular direction, only to find out later on imaging that the barrier was a bony one rather than a deficit in the muscular system.
What would the outcome have been if I’d taken a more aggressive approach? It certainly wouldn’t have altered the anatomical facts, and may have led to more degradation of the joint over time.
As a general rule, a muscular restriction tends to feel like tension — a sensation you might associate with a muscle under stretch. It may respond to targeted exercise over weeks and months. A bony restriction tends to feel more like a hard stop — less like a stretch and more like running into a wall. It doesn’t improve with time, no matter how consistently the work is done.
Work with your anatomy, not against it
None of this is an argument against the value of maintaining range of motion at your hips. Restrictions do occur and tissues benefit from regular movement.
The point is that working on range of motion should be targeted and under the control of your muscular system. Repeatedly driving a joint into a position where bone is meeting bone is not productive — it’s potentially injurious.
A deep squat, the splits, or a certain yoga posture might simply not be available to a particular body — not as a failure of effort, but a fact of anatomy. Recognising that is the starting point for intelligent, sustainable training that builds genuine capacity without quietly destroying a joint in the process.
The next time a hip movement feels more like a hard stop than a stretch, it might be worth pausing before pushing harder. The wall you’re running into might not be muscle at all.