Myofibrillar Hypertrophy: A Primer

Myofibrillar Hypertrophy: A Primer

Today we’re going to school to do a little bit of learning. I’m going to assume that if you’re reading this site you want a few things out of your physique.

You want to be lean.

You want to be mobile.

You want to be powerful.

Below you’re going to see part 1 of a post I wrote for a certain website but never heard back from (hey, you can’t win ’em all right?) This one is a bit more on the “knowing” side of the spectrum and part 2 will be more on the “do” side of the spectrum. So take a gander below and learn a thing or two about the types of hypertrophy and in the next installment you’ll have a basic outline on how to apply it to your training.


A powerful man, in the physical sense, is exactly what you think he’d be… well-built, in the lower levels of body fat percentage and capable of lifting multiples of his own body weight in certain exercises. The most common benchmarks are 1.5x his body weight in the bench press, 2.25x his body weight in the back squat, 2.5x his body weight in the deadlift and being able to perform 18 or more strict pull ups. Take a look at any sprinter, gymnast or Olympic lifter (except maybe some of the heavyweights) and you’ll see the best example of what a physically powerful body looks like.

Lately guys have been putting too much emphasis on other aspects and thinking that it will make them powerful. You don’t need bulging biceps. You don’t need 6-pack abs. You don’t need 4% body fat. You don’t need a Gold Medal hanging around your neck.

…But of course you knew that already.

What Does Powerful Look Like?

What you do need is shoulders wider than your waste, an appreciable amount of dense muscle, a little less body fat (or maybe it’s a lot, let’s be honest), legs that don’t resemble a broom handle and some “mass in the ass” so it’s not a straight line from your ankles to your shoulders.


Case in point...

All of these attributes cause an automatic reaction in others that tells them you’re strong, you’re fast and that you can handle moving you’re body in all dimensions of physical movement. Call it evolutionary, call it nature, or call it what ever you want. When you see someone with those attributes you take notice.


Had to cancel out the naked dude...

Bodybuilders and powerlifters are definitely powerful, there is no debating that. However, unless you’re ultimate goal is to get on stage at Mr. Olympia or squat 1000+ pounds you’re time is better spent taking a different approach. The approach we’re going to take will get you looking powerful and not require you to spend anymore time than necessary getting there.

Not to keep picking on the bodybuilder/powerlifter crowd, but most guys overestimate their ideal body weight by about 30 pounds. Even if they can hit that magical number, more often than not their body fat percentage is going to hide any proof of how much muscle they have and throw a wrench into the overall look. Not to mention the amount of time, dedication, and possibly drugs, that would be needed to maintain that look. You’re better off  stepping back and being a little more realistic with your goal.

In addition, if girls (and guys too) can swoon over Brad Pitt in Fight Club or Ryan Reynolds in Blade it should show you that 220+ pounds of pure muscle isn’t necessary. So how are we supposed to put on dense, strong muscle while still having a life outside of working out and at the same time get better at moving our body in every dimension? A good amount of that answer is in the difference between myofibrillar hypertrophy and sarcoplasmic hypertrophy.

Myofibrillar Hypertrophy

In the most basic sense a myofibril is a muscle fiber and hypertrophy is the growth of an organ, in this case muscle. Within the myofibril you have structures called myosin and you have structures called actin. If myosin is the hook part of velcro then actin is the loop part it hooks into. When these structures get the signal that they need to contract, the head of the myosin reaches out and attaches to the nearest actin. It then slides in one direction, releases from the actin and if still getting the signal attaches to a new actin and repeats the process causing the muscle to shorten even more. This ratcheting type movement occurs in unison with every myosin structure in the muscle fiber and this is what happens at the smallest level during muscle contraction.

With an increase in the number of these actin and myosin structures in each individual muscle fiber the amount of force that can be produced goes up. More tension created by the actin and myosin shortening the muscle means more force applied by the muscle. Since this type of hypertrophy will only cause a small amount of size and/or weight gain it is ideal for sprinters, MMA fighters, Soldiers, Marines and really anybody else who needs or wants to pack the most amount of force and strength into a smaller package. Barry Ross, writer of “Underground Secrets to Running Faster” calls it “Mass-Specific Force” and credits this approach to training to Allyson Felix winning the Silver in the 2004 Summer Olympics 200m dash….as an 18 year old.

The best approach to myofibrillar hypertrophy is to lift weights at 85%-100% of your 1 repetition maximum (1RM). At this percentage most sets will be only 1-6 repetitions and 3-6 sets will be plenty for most guys. Now, this is only if you are able to keep good form throughout the movement. If you are unable to keep good form you are more likely to injure yourself and, let’s face it, you can’t produce much force if you’re in a cast or laid up in a hospital bed after surgery. The best thing you can do is be stickler for form and not worry about hitting heavier weights right out of the gate.

Sarcoplasmic Hypertrophy

The actin and myosin are the structures that do the moving, the sarcoplasm is where everything from water to calcium to glycogen and everything else needed for the muscle to function properly is stored. A god analogy is to think of the actin and myosin as the engine in your car and the sarcoplasm as the gas tank. Oversimplified, maybe. But it’s a good start.

Everything that is non-contractile in nature is stored in the sarcoplasm. By aiming for this type of hypertrophy you will see the biggest gain in muscle cross section (IE. size) and it is what most bodybuilders focus on when preparing for a show. While muscles built by sarcoplasmic hypertrophy may look big and strong they aren’t ideal for producing maximum force and what force they are able to create is often offset by the weight gain that comes along with it.

The best approach for this type of hypertrophy, should it be your goal, is with weights around 75% of your 1RM. This percentage should allow you to get anywhere from 10-15 repetitions and 4-5 sets is more than enough. Again, just as with myofibrillar hypertrophy you must make a conscience effort to get perfect form before going with heavy weights.

Alright, stay tuned for part 2 in a day or so. That one will dive in a bit deeper to myofibrillar hypertrophy and lay out a basic approach on how to train for it.

Get strong stay strong!




  1. I thought this was very well put together and contained all the basic information needed to introduce someone to this topic. Very useful.

  2. your 100% correct I am surprised that more people have not agreed with this article
    i was once part of a boxing gym that told me not to get too big because it slows you down and reduces flexibility but the coaches there forgot to mention that if i focus on building fast twich type b dense non plasma filled muscle mass with methods that trigger myofibrillar hypertrophy like sprinting
    and oyl lifts with some 1rm work here and there i could become a machine but they are waay too old school so i increased my speed and strength as well as my coordination
    as best i could im squatting 400 and deadlifting 400, im running a 4 second 40 yard dash
    and can nearly do a side ways split, endurence wise i can run a 6 min mile.
    i applyed the power to my boxing skill which were greatly enhanced by your methods and i gained 45 pounds of fast contractile mass in 2 years i weigh in at 225 and im gonna go back this week after 2 years of building my bases and become a boxer again i plan to make
    the heavy weight/super heavy weight class popular again.