Pink Muscle: Is Akisame’s Training in Kenichi Humanly Possible?

By on April 20, 2020

Here on the Bioneer, I like examining the workouts found in anime, comicbooks, and movies, to see what’s possible. I believe that training should be exciting, and that we should be more ambitious about our goals. We shouldn’t be content to train like everyone else, but should find ways to express ourselves and push physical culture forward.

Fiction can be great source of inspiration.

That said, I hadn’t actually watched Kenichi: The Mightiest Disciple until people started asking me about the concept of “pink muscle.” This came up several times in fact, so I decided I’d tackle it quickly – as there seems to be some misunderstanding surrounding how muscle fiber works.

Shoutout: Jax Blade was the YouTuber to tackle this subject first! Check out his video on the subject for more on this awesome anime and how it could relate to real-world training.

pink muscle kenichi akisame

The idea is this: one of Kenichi’s masters, Akisame, has converted all the muscle in his body into what he refers to as “pink muscle.”

According to the show, there are three types of twitch muscle fiber: slow (red), fast (white), and in-between (pink). This correlates well with what we know:

We have:

  • Type 1 muscle fiber AKA slow twitch – This is oxidative muscle fiber that is used for aerobic exercise like running. It is slow to contract, smaller in size, and produces less force. However, it also allows you to exert yourself for longer periods. This fiber is indeed red in color, owing to the higher oxygen content.
  • Type 2x muscle fiber AKA fast glycolytic or superfast twitch – These are anaerobic and rely on ATP stored in the muscle. This allows for more explosive force and speed, but also fatigues much more quickly. You use type 2x during your one-rep max in an Olympic lift, or when sprinting at top speed off the starting block. This is incorrectly referred to as type 2b by like… everyone. Even my personal training textbooks (but fortunately not the neuroscience modules of my degree).
  • Type 2a muscle fiber AKA moderate fast twitch – These are intermediary muscles. They are useful for shorter durations of more intensive exercise such as lifting weights or running. They are less energy efficiency than type 1 fiber, but more fatigue-resistant than Type 2x.

What Akisame has allegedly done, is to convert all of his muscle to the pink type 2a and therefore achieved the perfect mix of explosiveness and endurance.

What Akisame has allegedly done, is to convert all of his muscle to the pink type 2a and therefore achieved the perfect mix of explosiveness and endurance.

Unfortunately, this is entirely fiction. Sorry to burst your bubble! Not only is this impossible, but it also wouldn’t be desirable even if it were.

But we can take some interesting ideas from it and us it to illustrate some things about the human body. As is often the case, the fact is stranger than fiction!

First the good news: contrary to popular belief, you actually can convert type 1 muscle fiber to type 2a. Moreover, a lot of muscle fiber in untrained individuals is actually made up from hybrid types, that are two types of muscle fiber at once. Training increases specificity by creating more pure fiber types.

Slow twitch fiber endurance

In reality though, a 10% change would be considered fairly impressive and much more than that starts to become unlikely. Type 1 muscle fiber is far less prone to changing type, so changing all your muscle fiber to type 2a is strictly only going to happen within the realms of fiction.

And there’s a good reason for this: you actually need a good amount of slow twitch muscle fiber. Apart from the fact that slow twitch is what allows you to run long distances (which even Akisame would need to do from time to time), there’s also the fact that slow twitch muscle works all the time to keep you upright.

The amount of each fiber type varies from one muscle group to the next. While your biceps consist of a lot of fast twitch (2a) fiber (just over 50%), your abs and calves consist of a lot of type 1 fiber. Why? Because your arms hang by your side all day until you need to use them – often for a strength-requiring movement. Conversely, your abs are slightly contracted all day just to keep you upright. If you were comprised of 100% fast twitch fiber, you’d eventually gas out and collapse because you’d be exerting so much force just to stay upright!

Slow twitch fiber dexterity

It’s also our slow twitch muscle fiber that gives us extremely fine motor control. When you engage in any movement, the brain needs to “recruit” motor units comprised of muscle fibers. These are arranged in size, so that you have some small groups of slow twitch fibers and some big groups of fast twitch fibers. Now let’s say you want to move your hand a millimeter in one direction during some calligraphy, or disarming a bomb. You’ll now want to apply just a tiny bit of pressure, and so you’d recruit a tiny amount of extra force from your small motor units. If you only have fast twitch fiber, then your arm will jerk suddenly in that direction and it’s game over.

If you want more proof that you need both types of fiber, just consider that this separation between type 1 and type 2 is seen all throughout mammals.

The other issue here is that converting all your muscle to type 2a would mean losing that type 2x muscle fiber: something that no athlete in their right mind would want to do!

Superfast twitch muscle is actually 20X more powerful!

Actually, most types of training – even lifting heavy weights – will change most of your type 2x fiber to type 2a. You only have an extremely small amount of 2x relative to type 2a. This makes sense, given just how inefficient 2x is from an energy standpoint. The only time you need to create more 2x is when you are moving extremely explosively, such as when lifting your 95% 1RM for an Olympic lift, or when sprinting off the starting block in a race.

But while fast twitch fiber is 5-6X faster than slow twitch fiber, superfast twitch is actually 20X more powerful! Those few superpowered fibers make a world of difference when it comes to your max strength and speed.

In short: you do not want to get rid of all of them!

Training for Your Fiber Type

But what lessons could we take from Akisame?

One interesting concept is training for fiber type.

Typically, when lifting weights, we will stick in rep ranges anywhere between 3 up to 20. In all these cases, we are training the type 2a muscle fiber predominantly. This makes sense for bodybuilders given that type 2 muscle fiber grows about twice as much in response to this kind of training (resulting in a more impressive physique). It makes sense for powerlifters too, who can still generate a huge amount of explosive strength this way.

Training for muscle fiber type

But if the powerlifter really wants to maximize their explosiveness, then they need to train at 95% of their 1RM to encourage the maximum amount of type 2X fiber involvement. Alternatively, they need to maximize rate force production by focusing on the most explosive movement possible (called compensatory acceleration). This could be combined with plyometric and ballistic-style training.

At the other end of the spectrum, it may also make sense to train in a manner that is going to fatigue the slower twitch muscle fiber. I’m not suggesting combining long-distance marathon training necessarily, but rather using those long drop sets and super-high rep ranges to fatigue all the muscle you can. The same goes for performing yielding isometrics to failure.

If we could flick that switch in human muscle, we might witness untold feats of speed, explosiveness, and athleticism.

In other words, I’m talking about getting to the point where you can’t lift the 5kg dumbbells any more, or perform even a single push-up. It’s only at that point that you have fatigued not only the biggest motor units, but also a good proportion of those slower ones. This can increase capillary density (slow twitch muscle fiber is supplied by a greater density of capillaries) and it can thereby improve work capacity, recovery, and more. PLUS you’ll be hitting both types of muscle fiber with the stimuli required for growth – meaning you can eke out a little extra size.

The Dormant Power in Your Cells

If we were going to imbue a fictional character with super-powered muscle fiber, there is a cooler and more realistic way we could do it.

Because locked away in your genome, is the potential for not 3, but 10 different myosin isoforms. These are dormant throwbacks to our evolutionary history, not normally expressed by our cells.

In theory, using gene doping or other future techniques, we might someday be able to unlock this hidden, ancient potential. That could include tapping into the true type 2b muscle fiber usually only found in small mammals like mice.

Dormant myosin isoforms in DNA

Ever wondered why mice move in such a jittery and explosive manner? The same goes for squirrels and other jerky little critters.

Well, that’s thanks to type 2b muscle fiber. And if we could flick that switch in human muscle, we might witness untold feats of speed, explosiveness, and athleticism.

About Adam Sinicki

Adam Sinicki, AKA The Bioneer, is a writer, personal trainer, author, entrepreneur, and web developer. I've been writing about health, psychology, and fitness for the past 10+ years and have a fascination with the limits of human performance. When I'm not running my online businesses or training, I love sandwiches, computer games, comics, and hanging out with my family.

One Comment

  1. Majk says:

    u really helped, arigato

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