Muscle Augmentation is a Quirk that gives its user the ability to amplify, and to a degree, manipulate their muscles, granting a significant increase in strength, speed, and durability. When using this Quirk, muscle fibers can be enlarged to the point where they can no longer be contained by the user's skin. In addition, Muscle Augmentation gives the user the capacity to contend with One For All at 100%.
While powerful, the brute force granted by this power can be bested by One For All users going beyond their 100% output. Another weakness of the Quirk is that in between the muscle fibres, the strands depleted of energy tend to rip and tear away. If someone with a Vibrate Quirk can destroy a several strands in one go then the user will not be able to use the Quirk properly for a while, leaving them vulnerable to attacks. Izuku exploits this weakness to easily defeat Muscular during their rematch.
Goto is the only wielder of this Quirk where it serves as his lone superpower. He uses Muscle Augmentation to cover his limbs with enhanced muscle fibers that protrude from his skin. For Goto, whenever any of his muscle fibers are depleted of their energy, they tend to rip and tear away from his body. He can freely choose which parts of his body his muscle mass covers in order to immensely increase his physical prowess. When fighting seriously, Goto can obliterate a large portion of a cliffside with a single strike.
The augmented muscles also provide Goto with heightened durability, as the fibers can act as a shield to absorb attacks. With enough protection, Goto can even easily endure the force of Super Moves as powerful as Izuku Midoriya's 100% Detroit Smash, which is equivalent to the strength of All Might.
By magnifying the muscles in his legs, Goto can move at blurring speeds that far outclass One For All: Full Cowl at 5%. Goto's inflated speed also gives him the option to completely avoid incoming attacks. In order to counter Goto's enhanced speed, Izuku purposely trapped his hand between the former's exposed muscle fibers so that Goto couldn't avoid his next attack.
All For One gave Wolfram the ability to enlarge his muscles and greatly increase his strength. When activated, Wolfram's muscles don't protrude from his skin, instead, they glow bright red, altering his appearance as a result. This is similar to how One For All at 100% changes the appearances of All Might and Izuku.
Combined with the Quirk Amplification Device, this Quirk gave Wolfram enough raw strength to momentarily overwhelm All Might and turn the tide of their battle. Using this ability, Wolfram was able to injure All Might and compensate for his weakness at close range when manipulating metal.
Hood mainly uses enhanced muscle fibers to support his other Quirks, giving him incredible destructive power. Hood can cover his arms and muscles, transform them into powerful tendrils, and increase their power even more by using it in tandem with another strength enhancement Quirk.
The brute force of this Quirk has shown to be levels above Muscular's own raw power, and allowed Hood to overwhelm Endeavor. Destroyed muscles can also be regenerated thanks to Hood's Super Regeneration.
- Aside from the transferable Quirk One For All, Muscle Augmentation is the second Quirk with the largest number of named users in the series, the first being Super Regeneration.
- In the Ultra Analysis databook, it is implied that Wolfram and Hood's Muscle Augmentation Quirks are potentially duplicates of Goto's original Quirk created by Doctor Kyudai Garaki.
- This Quirk functions identically to Muscle Expansion.
- My Hero Academia Manga and Anime: Chapter 76 and Episode 42.
- My Hero Academia: Two Heroes.
- My Hero Academia Manga: Chapter 308.
- My Hero Academia Manga and Anime: Chapter 75 and Episode 42.
- My Hero Academia Manga and Anime: Chapter 186 and Episode 87.
- My Hero Academia Manga and Anime: Chapter 188 and Episode 88.