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How Limb Lengthening Affects Muscle Size...and Vice-Versa

Jun 12, 2021

Today we’re going to talk about a question I’ve been asked quite a bit and that’s “how Limb Lengthening can affect your muscle size” after all is said and done. And then we’ll flip the script and answer the question of “do larger muscles affect limb lengthening” by making it harder than it needs to be.

Alright so, let’s say you get limb lengthening on your tibias and a year or two later you realize your calf muscles are bigger than they were before surgery, even though you’re doing the same type of activity and training. What happened - how’d your calves get so much larger from limb lengthening surgery?

A great question but in order to answer it, I have to first explain how muscle growth happens.

So real quick, there’s two ways a muscle can grow bigger, either Hypertrophy which is an increase in size of the muscle fibers due to the overload placed on them, cellular swelling of fluid and or growth factors. OR the other way is by Hyperplasia, which is when the actual number of muscle fibers increase leading to a greater cross-sectional area of that tissue thus increasing your muscle growth capacity.

It’s been said that, naturally, only hypertrophy can happen in the skeletal muscle of adult humans and that hyperplasia can’t, that it’s a myth. However, Dr. Jacob Wilson, also known as the muscle PhD, wrote an awesome article where he explains how, although it’s rare, hyperplasia CAN IN FACT occur.

He cites some research on how it’s been shown in other animals like birds, mice, and even fish that undergo hyperplasia under various conditions. He also refers to one study on humans where the right and left tibialis anterior muscles of adult men were exposed to different weight loads. The muscle under the higher weight load showed a greater cross-sectional area meaning more muscle fibers and thus hyperplasia.

Dr. Wilson touches on other topics that also circle back to the premise that a given muscle under a large stimulus like heavy weight, in a maximally stretched position, (hint-hint), can result in hyperplasia.

One of these interesting topics he refers to is known as fiber splitting, when a muscle fiber will actually split apart to maintain its function.

So how does Fiber Splitting happen? Well, it can happen given THREE stimuli; one is like Dr. Wilson said, under maximum load in a “maximally stretched position”, The other two is “oxygen diffusion capacity” meaning after a muscle fiber grows large enough it’ll require more oxygen than is readily available and will need to split off for some breathing room. And the third possibility is known as the “Myonuclear Domain Theory” which essentially states that myonucleus can only govern a given domain of the muscle fiber, and outside that jurisdiction, you’ll need a new fiber and myonucleus.

In simpler terms, this is all basically saying that if a muscle fiber is overloaded with weight and stretch, suffocated due to lack of oxygen or overcrowded it’s going to need to move to a new town, with a new sheriff, and fast.

Alright, now that you understand the context of how muscle growth and fiber splitting occurs, it’s time to finally answer that question of how limb lengthening can affect the muscles of your lengthened limbs.

So we all know that during limb lengthening of the bones, the muscles and soft tissues come along for the ride. Well, after a certain amount of length (and this can vary for each patient), that muscle will hit it’s threshold and thus run out of reserve slack, undergoing maximal stretching and extreme eccentric loading (either by your own body weight or when you lift weights) which will result in fiber splitting - hyperplasia.

Now typically, to naturally induce hyperplasia it would take years of doing this stretching and loading, however limb lengthening is far from typical and so the same effect can be expedited in just months.

Another way limb lengthening could affect your muscle size, is by biomechanical leverage differences. When you lengthen your bones, you’re literally changing the anatomical structure of your limbs and thus the mechanics which could then lead to how the attached muscles handle load.

For example, let’s say after lengthening your femurs, it’s possible the middle part of your hamstring, the semitendinosus, may have to take on some of the load that the biceps femoris usually would, resulting in more mass of the muscle belly.

And research also backs this up. In that fiber splitting article, they removed a portion of the gastroc-soleus in a mouse subject, leaving the much smaller and weaker plantaris muscle to bear the brunt of the load and it actually grew a much greater cross-sectional area meaning it underwent hyperplasia.

I, myself, can also personally attest to this in my own limb lengthening case of my lower left leg. My soleus and gastrocnemius on my left leg are bigger than my right and have actually grown stronger too over the years that I’ve been training.

So yeah, after limb lengthening it’s likely you will grow bigger muscles due to hypertrophy and possibly even hyperplasia.

Now let’s flip the script and talk about if larger muscles make limb lengthening harder than it needs to be. The short answer is yes, but the big caveat is if you’re not flexible enough.

This means you can have big leg muscles with maximal range-of-motion flexibility and be just as good off as someone who has a ¼ of the muscle mass and yet you both experience a similar limb lengthening process and achieve similar results.

Now if you’re anticipating lengthening in the next 6 months, then you can focus more on strengthening your muscles without adding significant muscle mass. But you know what, coming from a pro natural bodybuilder, it’s incredibly hard to build anywhere close to enough actual lean muscle mass that will negatively impact your lengthening (assuming you’re flexible enough) or unless you’re some genetic freak and can build muscle by looking at weights.

So basically, don’t worry about it, just stretch a lot before surgery and you’ll be fine.

And also the good news is if you’re considering cosmetic stature lengthening to get taller, you shouldn’t have to worry too much about how limb lengthening will affect muscle size since you’ll be symmetrical in both appearance and eventually strength. However if you’re a discrepancy patient you should do a lot of unilateral training to maintain symmetry, and strength balance - trust me it helps.

Citations:

Dr. Jacob Wilson Muscle PhD: https://themusclephd.com/hypertrophy-...

Fiber Splitting Article: https://www.ncbi.nlm.nih.gov/pmc/arti...