CS Sports Physio

Are you struggling to get your quad going post surgery ?

AMI (arthrogenic muscle inhibition) doesn’t respond to effort. It responds to the right stimulus.

One of the hardest things about the acute phase of ACL rehab is that it can make a disciplined, high-performing athlete feel like they have no control over their own body.

You’re doing the work.
You’re showing up.
And your quad still looks flat and fires like it’s working through wet concrete.

That experience is not a fitness problem.
It is not a motivation problem.
It is a nervous system in protective mode, doing exactly what it is designed to do when a joint is under threat.

What makes this particularly important to understand is that AMI doesn’t automatically resolve as rehab progresses. Athletes who move into the strengthening phase with significant inhibition still present will hit a ceiling, the quad can’t produce force it hasn’t been allowed to recruit.

The strength gap that develops in phase one becomes the asymmetry that fails return-to-sport testing in phase three.

The acute phase is the window to address this.
NMES,
BFR,
Quality of contraction over volume

These are not advanced interventions. They’re appropriate interventions for the specific problem that’s actually there.

If nobody has explained AMI to you, you now have the language to ask about it

Extension loss is one of the most preventable complications of ACL rehab.
It’s also one of the most missed.

The reason it gets missed is that it doesn’t announce itself. There’s no alarm that fires when you’re sitting three degrees short of full range.

Rehab continues.

Strength work starts.

Return to sport criteria get ticked.

And the deficit travels with you through every single phase, quietly changing how your knee loads, how your graft heals, and how your gait looks at speed.

The athletes who end up in a physio’s room at month eight wondering why something still doesn’t feel right, a significant number of them have an extension deficit that was present in week two and never fully addressed.

It is not complicated to fix in the acute phase.
It becomes complicated when it’s left.

The four causes covered in this carousel are not interchangeable. The fix for quad guarding is not the fix for posterior capsule tightness, and treating one like the other is why extension work stalls. Knowing which problem you’re dealing with is the difference between progress and repetition.

Check your extension daily. Match it to your other leg. If it’s not moving in the right direction, don’t wait

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‼️ You can’t rehab a swollen knee. You have to earn the right to exercise first.

After ACL reconstruction, the joint fills with blood and synovial fluid.
That creates intra-articular pressure and that pressure has a direct effect on your ability to recruit the muscles around the joint.

This isn’t a comfort issue.
It’s a function issue.

Elevation means heel above hip, lying down, multiple times a day.
Not foot on a stool while you sit at a desk.

Consistent compression throughout the day, not just when the knee feels tight.

And avoid heat in the first 72 hours it vasodilates and increases swelling, which is the opposite of what you need.

Ice reduces pain and makes early movement more manageable, but it doesn’t drain the joint. It’s a support tool. Compression and elevation do the structural work.

There’s also a specific neurological reason why unmanaged swelling blocks quad recruitment and it means you can do a hundred quad sets and barely activate the muscle.

That’s covered in post four of this series. Worth understanding before you question why early rehab feels unproductive.

Get the swelling under control first.
Everything else in the acute phase depends on it.

Post three covers why your knee won’t fully straighten and what’s actually causing it.

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4 targets. One phase. Miss them, and you’ll be playing catch-up for months.

Most ACL rehab programs treat the acute phase like a waiting room.

There’s no load, no gym, nothing that looks like progress, so it gets rushed or ignored.

That’s a mistake.

What happens in the first four weeks sets the quality of everything that follows.

Swelling control, full extension, quad activation, gait pattern these aren’t optional.

They’re structural.

Skip them and phase two becomes a lot tougher.

Over the next few weeks I’m running a six-part series covering each target in detail.

1️⃣ Why swelling management matters beyond just comfort.
2️⃣ Why extension loss compounds if you don’t catch it early.
3️⃣ What arthrogenic muscle inhibition is and why standard exercises won’t fix it.
4️⃣ Why your gait pattern matters before you ditch the crutches.
5️⃣ And a phase progression checklist - three things that need to be in place before you add load.

Each post will build on the last. Connecting them all in ways that aren’t obvious at first

The acute phase may not look fun. That doesn’t mean it isn’t important.

👉🏼Make sure you’re following along!