Conor Harris Profile picture
Mar 13, 2024 16 tweets 6 min read Read on X
A thread on hip mobility: How to assess it & how to improve it

The average human hip has ~95 degrees of a total arc of external & internal rotation (ER/IR) available:

✅45 degrees of ER
✅40 degrees of IR

But many people have so much less than that. In order to improve it...Image
We should first know why it’s important.

The femur (thigh bone) needs to rotate within the hip socket in just about any dynamic activity.

We also know that if the body is lacking mobility where it should have it, it will find it somewhere else (joint-by-joint concept). Image
In order to measure it, it’s very important to get an accurate measurement the first place.

See here:
This is where people initially go wrong.

It is very easy to “fake” hip range of motion via compensation and moving through the lumbar spine.

A general rule is we will “roll away” from the leg to find internal rotation.

You’ll see the leg push inwards:
And we will “roll towards” it to find external rotation.

You’ll see the leg push out and the other (down-side leg) also potentially move.

People will have much less genuine range of motion than you actually think.
Generally speaking, if someone is missing hip IR it’s usually because they are stuck in a position of hip & pelvic external rotation.

This (again, usually) means that the muscles on the back side of the pelvis are tight. Image
The inverse would be true for ER limitations. Tightness of hip flexors and IR muscles can limit leg ER.

These people are also often in an anterior pelvic tilt which allows them to pick up IR, but limits the ability for the femur to rotate into ER. Image
This is the general idea, but there are also contexts in which you are really far into anterior or posterior pelvic tilt that you can’t move further into a position you are already in.

So either IR or ER becomes limited, respectively.
To improve IR, I recommend using positions that bias internal rotation naturally.

Good ways to do this are:
- Positions in 90 degrees of hip & knee flexion (bend)
- Activating muscles that create IR (inner hamstrings, glute med, and adductors)

(Exercise credit @postrestinst)
- Hinges bias more IR because of the amount of hip flexion and IR required to move into that position.

We can improve it even more by staggering the stance which will bias more IR on the rear leg.

The added toe elevation ⬆️ IR as well via biasing foot dorsiflexion & shin IR:
Sometimes it’s necessary to “stretch out” the back hip capsule to improve the ability to slide the femur back in the first place.

If you are struggling, try this:

(This is a modified @postrestinst exercise):
To improve ER, I recommend facilitating the glutes (hip ER muscles) as well as the hamstrings which help pull the pelvis back out of an anterior pelvic tilt.

Here is one drill you can use to do that:
External rotation is also needed for the deepest levels of hip flexion (hip bend).

We can bias & work through that in a position like this:
A heels elevated, deep squat with a band keeping the knees in line with the toes can also work well.

Be sure to go slow and control the tempo as I describe:
Ultimately it is important to have a thorough assessment process.

Only going off of one assessment is not going to give the best indications as to what could be happening or limiting movement.

This is only one perspective, but a helpful one when digested in the right context.
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More from @Conor_Harris_

Jan 21
The reverse plank might be the single most underrated exercise for fixing slouched posture (thoracic kyphosis).

Why?

Because it addresses the real underlying issues at both your shoulders and hips.

Here’s why it works, and how to do it 🧵 Image
Most people think “fixing posture” is about pulling your shoulders back.

That’s not the case.

Slouched posture often stems from:
•Limited hip extension - the ability to get the legs under us properly
•Limited thoracic extension - secondary to a tight front ribcage
The reverse plank fixes these by:

✅ Driving hip extension with the glutes & hamstrings
✅ Moving your arms behind your body into extension
✅ Opening the chest & elevating the sternum
✅ Restoring front-side ribcage expansion
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Sep 3, 2025
The Tibialis Posterior is one of the most underrated muscles for fixing knee, ankle, and foot pain.

Weakness here shows up in countless injuries - yet most rehab overlooks it. Let’s break down why it matters & how to train it 👇 Image
1️⃣ Why it’s so important
Research links a weak tibialis posterior to ankle & foot pain.

This muscle originates on the back of the shin and runs behind the medial ankle, under the foot. Its unique position makes it essential for arch control.
2️⃣ Controlling pronation
When your foot hits the ground, the arch naturally lowers (pronation).

The tibialis posterior decelerates this motion so it happens in a controlled, healthy way. Weakness = arch collapses too far, too fast.
Read 10 tweets
Sep 1, 2025
Struggling to squat deep without buttwink or your back rounding?

Most people blame it on ankle mobility… but that’s only part of the story.

Here’s what you need to know to fix your squat at the root cause 🧵 Image
The real question: why is ankle mobility limited in the first place? Image
One underrated reason 👉 Your body’s center of gravity is shifted forward.
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Aug 29, 2025
Most people are missing one key piece of hip mobility.

And if you don’t have it, your low back is the one paying the price.

Let’s talk about hip extension 🧵 Image
Hip extension = your ability to bring your leg fully under you and slightly behind you.

It’s one of the most commonly limited motions I see when assessing clients. Image
Why does it matter?

If you can’t extend at the hip, your body will find a workaround:

👉 Arching the low back instead.
This creates repetitive stress on the spine.
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Aug 25, 2025
Most people think Sciatica is caused by a tight piriformis muscle.

But the piriformis is usually just the messenger, not the root problem.

Here’s what’s really going on (and how to fix it)… 🧵 Image
Most people with sciatica think the issue is their piriformis muscle being too tight and pressing on the sciatic nerve.

So, they stretch it or roll it out for temporary relief…

But that tight piriformis is usually just a symptom of something bigger. Image
The real problem often starts with your body’s center of gravity shifting forward. This is what I commonly see in my clients with Sciatica.
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Aug 20, 2025
One of the most overlooked culprits in stubborn low back pain?

👉 The Quadratus Lumborum (QL).

It’s tight, overactive, and pulling your spine out of balance more often than you think.

Here’s why it matters and how to fix it 🧵 Image
First, it’s key to understand that the QL runs between your pelvic crest and lowest rib. Image
When it gets short and tight, it has 2 main effects:

•Both sides: compress + extend your low back (arching)
•One side: side-bend the spine, pull the shoulder down + hike the hip up
Read 11 tweets

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