Will Wearing AFOs Make Me Weaker if I Have CMT?

This is the most common—and most understandable—question I hear from people living with Charcot-Marie-Tooth (CMT) disease. It is the most common reason why CMT patients delay or simply don’t want to consider wearing AFOs.

“If I start wearing AFOs, won’t my muscles get weaker?”

It’s a fair concern. We all know instinctively that when we stop using our muscles, they get weaker. So, it seems logical to worry that AFOs might “do the work” and allow the muscles in our lower legs to go on vacation and consequently, get weaker.

First, Let’s Be Clear About How CMT Causes Muscle Weakness

CMT is an inherited progressive peripheral neuropathy. Peripheral nerves are those nerve cells that are outside of our brain and spinal cord. CMT is a nerve disease, not a muscle disease.

CMT causes muscle weakness by affecting the peripheral nerves that innervate our muscles. Our peripheral nerves are like the power cords that power electric motors.  Each peripheral motor nerve cell makes a non-stop flight all the way from our spinal cord to each muscle. Same for our peripheral sensory nerves that send signals from our muscles back to our spinal cord.  These nerve cells are tiny, microscopic, but can be strikingly long. One peripheral nerve cell can be up to 3 feet long in someone 6’ tall. The weakness begins distally at our toes and progressively works its way up the legs. The longer nerves are affected first, kind of like the roads we drive on. If suddenly all maintenance on all roads stopped, the longer roads would have proportionally more potholes, cracks and wash outs than the shorter ones and consequently, would become impassable (non-functional) first. As the peripheral nerves fail, we lose a commensurate amount of muscle strength.  It is functional muscle strength that matters most for CMT patients. The muscle can either complete its task or it can’t. 

Immobilization will also cause muscle weakness and atrophy. 

We see this often when:

• a cast is applied for 12 weeks to heal a broken bone
• after surgical fusion
• even after amputation 

Our muscles work and remain strong by contracting as they shorten (concentrically) and as they lengthen (eccentrically).  Our muscles need to lengthen and shorten throughout a specific range of motion for optimal power and control. 

Muscles that are prevented from lengthening and shortening throughout this normal range of motion will weaken from disuse. 

• It makes sense that AFOs designed to limit motion, or worse, completely immobilize the foot and ankle will result in muscle weakness and atrophy from disuse.  
• *Unfortunately, one of those compensatory strategies employed by CMT patients is a “guarded gait pattern”. This is where the patient intentionally limits the motion of the pelvis which does cause disuse weakness of our proximal muscles 

So the real question isn’t: “Will AFOs make me weaker?”

The real question is: “Are there any AFOs that restore function without limiting normal range of motion?”

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What the Research Shows

I’m often asked if there are any independent controlled studies that discuss weakness associated with AFO wear for CMT patients.

Interestingly, there are no independent controlled studies that demonstrate measurable muscle weakness from AFO use with CMT.

There are a few published studies looking at people with CMT who use dynamic carbon ground reaction AFOs that consistently show:

• Improved walking speed
• Better stability and balance
• Reduced fatigue
• Lower energy cost of walking

In other words, with the right AFOs and gait training with them, it’s possible for CMT patients to walk with normal ankle motion (kinematics) facilitating restoration of a normal gait pattern, (what I call the essential elements of human gait).

The Wrong AFOs 

Too many patients I see are in the wrong AFOs which do immobilize their feet and ankles and conceptually, this would (as everyone suspects) cause weakness as the muscles are prevented from functional lengthening and shortening under load.  Dynamic carbon ground reaction AFOs are designed to control normal motion, not eliminate motion like a solid ankle AFO, surgical fusion or a cast. 

There are multiple studies in CMT populations using AFOs which show:

• Improved walking speed and stride length 
• Better ankle kinematics and reduced foot drop 
• Lower energy cost of walking (i.e., less fatigue) 
• Improved balance and gait efficiency 

Example: A dynamic carbon ground reaction AFO with an anterior shell reduced metabolic cost of walking in CMT patients, meaning they could walk longer with less effort 

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Understanding the Role of an AFO

An AFO is not there to replace healthy muscle.

It is there to assist muscles that are no longer able to do their job effectively and restore balance.

Think of it this way:

• If you can’t pick up your forefoot during swing,
• If your ankle collapses laterally when you load it,
• If you’ve lost propulsive power at push-off…
• If you stand and walk back on your heels
• If you can’t stand in open space and watch an eagle fly overhead

Then your body starts to employ energy robbing compensatory gait strategies:

• Lifting the legs and feet higher (steppage gait)
• Locking the knee back to prevent unexpected buckling
• A guarded gait pattern with shorter stride lengths, limited pelvic motion and keeping the arms in low guard
• Downward gaze to avoid hazards
• Excessive anterior and lateral head and shoulder motion 
• Overusing proximal muscles with preserved strength, to control weak unstable ankles and knees

These energy robbing compensatory gait strategies come with a cost:

Dynamic Carbon Ground Reaction AFOs are able to restore lost function, not to take away function that’s still there.

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Do AFOs Reduce Muscle Use?

Yes—in that they reduce demand on muscles that are already failing.

But that’s not a bad thing.

In fact, it’s often exactly what’s needed.

Instead of asking weak muscles to perform beyond their capacity, AFOs:

• Allow more energy efficient normal movement throughout the gait cycle
• Reduces overuse and early fatigue of affected muscles
• Improves skeletal alignment and control
• Helps you stay active longer

And staying active is one of the most important things you can do to preserve overall strength of unaffected muscle groups. As you walk more biomechanically, your unaffected muscles are used as they were intended and maintain functional strength.

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The Real Risk Isn’t Weakness From AFO Use—It’s Using the Wrong AFOs

Here’s what I see far more often:

• CMT patients wearing AFOs that are too rigid immobilizing the ankles when it’s not necessary
• CMT patients wearing AFOs that are too flexible and can’t restore meaningful function eg;
  • Balance 
  • Propulsive power for “push off” .
• CMT patients not wearing AFOs that end up taking up space in the closet

When AFOs don’t restore meaningful function, patients prefer not to wear them.
This is why proper evaluation, customization, and training matter so much.

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A Better Way to Think About It

Instead of asking:

“Will these AFOs make me weaker?”

Ask:

“Will these AFOs allow me to take back my mobility and get back to doing the things I want to do?

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How This Relates to CMT Mobility Rescue

At CMT Mobility Rescue, our entire approach is built around one idea:

How much mobility can I take back? 

We don’t just fit AFOs—we:

• Analyze how CMT specifically affects your mobility. 
• Identify what specific function has been lost
• Select the best AFOs to restore that function
• Train you to use them effectively in real-world “off site” environments

The goal is not just to eliminate foot drop. 

The goal is to help you take back all the functional elements of gait that CMT has stolen:

• Walking speed
• Propulsive Power
• Balance
• Overall confidence
• Reduce fatigue
• And keep it that way

Because in CMT, maintaining function is everything.

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Bottom Line

CMT causes weakness—The right AFOs do not!

AFOs are simply tools. Like any tool, the better your skills are with them the better you will do. AFOs combined with the skills to use them, allows you to use what you have more effectively and compensates for what you’ve lost.

If you’re wondering whether the right AFOs could help you, or if your current AFOs aren’t giving you the results you hoped for, that’s exactly what we focus on at CMT Mobility Rescue.

Because you deserve to get back the mobility stolen by CMT.