Why did Deku's arm not break when he hit Nomu?


In the last episodes of season one _Boku no Hero Academia_ , the League of
Villains attacks class 1A while they are at the USJ building. A fight breaks
out, and Shigaraki Tomura is about to use his quirk on Tsu's face, Midoryia
jumps into action and is about to hit Shigaraki when Nomu appears in the way.
The thing is, Midoryia hits Nomu with 100% of One For All and it does nothing
to Nomu and there is no backlash to Midoryia's arm. I know that one of Nomu's
many abilities is that he has "Absorption", which explains why it had no
effect on Nomu, but what made no sense was the explanation of why it didn't
affect Midoryia's arm. Midoryia thought it was because he was fighting a live
being, but I immediately regard this as illogical because in season two, there
are numerous occasions when he's fighting a person and he goes all out and
still harms himself. This is all before he figures out how to sustain the use
state of One For All at 8%(Full Cowling). So, I was wondering if someone could
shed some light on this. Anything would be appreciated.




I would suspect that it is more of due to him unconsciously holding back the
power of OFA.

He mentioned to All Might that he felt as if it was like an egg in the
microwave which does not explode (correct me about this quote if I am wrong).
An egg tends to explode in a microwave but it will not if there is not enough
heat; similarly, it could be perceived that the egg is Midoriya's body while
the microwave is the overwhelming power of OFA. Due to the 'microwave' not
producing enough heat, which is OFA's power in this case, it also resulted in
the 'egg' not exploding, which is Midoriya's bones not breaking. This thus
proves the point that Midoriya was indeed holding back his power.

There are many possible explanations as to how he held back his power without
knowing, but I feel that the most plausible explanation for this would be that
Midoriya's adrenaline 'controlling' him. As seen in his fight with Muscular,
Midoriya was somehow able to use 1,000,000% despite never using it before, and
also felt no pain from his injuries. It was then mentioned by Aizawa that
Midoriya was running on adrenaline. It could be possible that the rush of
adrenaline he felt from almost dying by Muscular and him picturing Tsuyu dying
by Shigaraki caused him to bring his power to new levels, or hold the power
back from hurting him too much.




I would suspect that it is more of due to him unconsciously holding back the
power of OFA.

He mentioned to All Might that he felt as if it was like an egg in the
microwave which does not explode (correct me about this quote if I am wrong).
An egg tends to explode in a microwave but it will not if there is not enough
heat; similarly, it could be perceived that the egg is Midoriya's body while
the microwave is the overwhelming power of OFA. Due to the 'microwave' not
producing enough heat, which is OFA's power in this case, it also resulted in
the 'egg' not exploding, which is Midoriya's bones not breaking. This thus
proves the point that Midoriya was indeed holding back his power.

There are many possible explanations as to how he held back his power without
knowing, but I feel that the most plausible explanation for this would be that
Midoriya's adrenaline 'controlling' him. As seen in his fight with Muscular,
Midoriya was somehow able to use 1,000,000% despite never using it before, and
also felt no pain from his injuries. It was then mentioned by Aizawa that
Midoriya was running on adrenaline. It could be possible that the rush of
adrenaline he felt from almost dying by Muscular and him picturing Tsuyu dying
by Shigaraki caused him to bring his power to new levels, or hold the power
back from hurting him too much.

