Pump Up 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, Pump Up 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 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 covers 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. Goto can can cover his body in more than 12,000 layers of muscle. 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.
- Pump Up's Japanese name, "Kin'niku Zōkyō" (
筋 肉 増 強), is the same as Muscle Augmentation's.
- The function of Pump Up is identical to Muscle Expansion and Muscle Augmentation.